============================================================================== Claude Code session : c0c8c8a0-e237-4540-bae3-488162b80dd9 Project directory : /home/agent/TE_ting Started : 2026-07-19 09:41:40 Ended : 2026-07-19 10:30:43 User prompts : 1 Claude Code version : 2.1.215 ============================================================================== [2026-07-19 09:41:40] user: The Teenage Engineering EP-2350 is connected. It's REPL is available at /dev/ttyACM0. Right now it is running stock Micropython firmware. Your goal is to help investigate the LED pins. Read ./power_hold_findings.md for information about the device and how to keep it awake. There are 8 total LEDs on the device, 4 red and 4 white. We want to figure out which pins they're connected to and what the control scheme is. There is a USB camera connected and looking at the device. You can get a photo from it with an ffmpeg command like this: ```ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2" -frames 1 out.jpg```. Right now I believe all 8 LEDs are light dimly, they can go brighter than they are currently. Please make and run the appropriate tests to figure out how to control the LEDs. [2026-07-19 09:41:42] agent: I'll start by reading the findings doc and checking the current state. [2026-07-19 09:41:43] tool use: Read file_path: /home/agent/TE_ting/power_hold_findings.md [2026-07-19 09:41:43] tool result: Read 1 # EP-2350 power-latch / auto-sleep mechanism — SOLVED 2 3 Session date: 2026-07-19. Method: stock MicroPython v1.25.0 (RPI_PICO2) over the 4 raw REPL (`scratchpad/rp.py`), plus manual handle press/release testing by the 5 user. Static analysis of `ep-2350_firmware_1_0_8.uf2` was also done but the 6 answer came from live probing. 7 8 ## TL;DR 9 10 > See also `button_findings.md` (all 5 buttons) and `volume_knob_findings.md` 11 > (GP29 is the volume pot — this file's "GP29 tied to 3V3" is wrong; corrected 12 > inline below). 13 14 | Signal | GPIO | Sense | Status | 15 |--------|-----:|-------|--------| 16 | **POWER HOLD / latch control** | **GPIO2** | drive **HIGH** = stay powered, **LOW** = power off | **Confirmed** | 17 | **Handle switch sense** | **GPIO19** | **0 = handle pressed**, 1 = released | Confirmed | 18 | VBAT / VBUS / analog sense | GP25, GP26, GP28, GP29 | external pull-up / divider | Likely (see below) | 19 20 **There is no power-management chip on the I²C bus.** A scan under stock 21 MicroPython returns only `0x18` (accelerometer) and `0x1b` (NAU88L21 codec). 22 The power control is a discrete latch driven directly by **GPIO2**. 23 24 To keep the device alive under your own firmware, this is all you need: 25 26 ```python 27 from machine import Pin 28 hold = Pin(2, Pin.OUT, value=1) # assert before the handle is released 29 # ... and to power the unit off: 30 hold.value(0) 31 ``` 32 33 ## How the circuit behaves (observed) 34 35 1. **At power-on the latch is OFF.** The handle switch supplies power directly 36 while it is held. This is why stock MicroPython dies the instant the handle 37 is released — nothing ever asserts GPIO2. 38 2. **Driving GPIO2 HIGH sets the latch.** With GPIO2 high, releasing the handle 39 leaves the device fully powered and the USB REPL connected. 40 3. **The latch retains state when GPIO2 floats.** After setting the latch, all 41 GPIO output-enables were cleared (`GPIO_OE = 0x0`) and the device stayed 42 powered for minutes with the handle released. So GPIO2 is not a 43 continuously-refreshed "keep-alive" — it is a genuine set/reset latch (or a 44 push-button power-controller IC), not an RC/charge-pump hold. 45 4. **Driving GPIO2 LOW resets the latch → immediate power off.** USB drops 46 instantly. This is the firmware's shutdown path. 47 48 So the TE firmware's documented behaviour is pure software timing on top of this: 49 it watches GPIO19 for the handle release, runs its 5-minute power-save timer and 50 20-minute off timer, and then drives GPIO2 low to cut power. On USB it simply 51 never drives GPIO2 low. 52 53 ## Evidence chain 54 55 - **Shotgun test.** 19 plausible pins driven high + a 1 MHz square wave on GP16; 56 handle released → device stayed alive. Latch is in that set. 57 - **Invalid first bisection (recorded as a caution).** Progressively releasing 58 pins kept the device alive, which looked like a bisection but was not: the 59 latch was already *set* and simply retained. Any "does it stay alive" bisection 60 must power-cycle between trials. The corrected method drives pins **low** one 61 at a time within a single latched session. 62 - **Low sweep.** With the latch set and the handle released, candidates were 63 driven low one at a time: GP1 low → still alive; **GP2 low → device died.** 64 - **Clean confirmation.** Fresh power-on, `GPIO_OE = 0x4` (GP2 the *only* driven 65 pin, high), handle released → alive continuously for the full observation 66 window. 67 - **Cross-check with the TE firmware.** The read-only pin snapshot in 68 `pinmapping_findings.md` §4 shows GPIO2 as the **only pin driven HIGH** 69 (`2 PIO0 OE=1 IN=1`). At the time it was noted as unexplained; it is the 70 power hold. (TE drives it from PIO, but a plain SIO high works fine.) 71 - **Handle sense.** GP19 read 0 (hard-driven low, beating a 2 mA MCU drive) while 72 banded, and 1 after release, across several cycles. It is a switch to ground. 73 74 ## External-drive map of every GPIO (stock MicroPython, nothing else driving) 75 76 Only these pins have anything external attached; everything else floats: 77 78 ``` 79 GP14, GP15 external pull-up I2C1 SDA/SCL (codec + accelerometer) 80 GP19 driven LOW handle switch to GND (0 = pressed) 81 GP28 divider ADC2 — the only real analog sense line 82 GP29 low impedance ADC3 — ⚠️ NOT a rail tie: this is the VOLUME 83 POT wiper. It only looked tied to 3V3 because 84 the knob was at max. See volume_knob_findings.md 85 GP1,GP3,GP21 (floating here) buttons — only pulled low while pressed; 86 see button_findings.md 87 GP20 driven LOW state-dependent, see caveat below 88 ``` 89 90 ### Analog sense lines — measured 2026-07-19 (USB powered, **no batteries fitted**) 91 92 Raw ADC, then each net loaded with the internal pulls (~50–80 kΩ) to measure its 93 source impedance. Loading is what separates a real divider from a floating pin: 94 95 ``` 96 pin float pull-up pull-dn swing verdict 97 GP26 1.365 V 3.101 V 0.105 V 2.996 V floating / unconnected 98 GP27 1.604 V 3.182 V 0.100 V 3.082 V floating / unconnected 99 GP28 1.630 V 1.755 V 1.500 V 0.255 V REAL DIVIDER, R_th ≈ 4.6 kΩ 100 GP29 3.290 V 3.290 V 3.288 V 0.002 V ⚠️ VOLUME POT at max, not the rail 101 ``` 102 103 **GP28 is the only genuine analog sense line.** Its ratio against what was 104 assumed to be the rail is `1.630 / 3.290 = 0.4954` — an almost exact **1:2 105 divider**, and 106 `R_th ≈ 4.6 kΩ ≈ 10k‖10k`. Both point to two equal resistors sensing the system 107 rail, i.e. **GP28 = VSYS/VBAT ÷ 2** (`get_vbat`). The competing reading — 108 VBUS ÷ 3.2 via 15k/6.8k, giving VBUS = 5.2 V — fits the impedance about as well 109 but requires an arbitrary ratio, so it is the weaker explanation. 110 111 > ⚠️ **Correction (2026-07-19, later):** the ratio argument above divides by 112 > GP29, which is **the volume pot wiper, not the rail** — it read 3.290 V only 113 > because the knob happened to be at maximum. The `R_th ≈ 4.6 kΩ` evidence for 114 > GP28 being a real divider still stands, but any GP28-vs-GP29 *ratio* must be 115 > recomputed against a genuine rail reference. Same for the batteries-fitted 116 > table below, whose "GP29 = rail/VREF" column only shows that the knob was not 117 > touched between the two runs. See `volume_knob_findings.md`. 118 119 **This is not yet decided.** The decisive test needs batteries fitted and USB 120 then unplugged: a VBUS sense collapses to ~0 V, a VSYS/VBAT sense holds at 121 ~1.5 V (3 V ÷ 2). That cannot be done with no batteries in the unit, because 122 unplugging USB removes all power. 123 124 `get_vbus` may well be a *digital* VBUS-present pin rather than an ADC channel; 125 no candidate identified yet. 126 127 #### One suggestive (not conclusive) data point 128 129 | condition | GP28 | GP29 (rail = ADC VREF) | 130 |---|---|---| 131 | USB only, **no batteries** | **1.630 V** | 3.290 V | 132 | USB + **batteries fitted** | **1.505 V** | 3.292 V | 133 134 GP28 moved by −7.7 % while the rail/VREF stayed put, so the change is real and 135 not a reference shift. A pure VBUS divider should not care whether batteries are 136 present, which **leans toward GP28 being a battery/VSYS sense**. `1.505 × 2 = 137 3.01 V` is a very plausible 2×AAA reading. 138 139 Treat this as suggestive only: between the two measurements the USB cable was 140 unplugged and replugged and may have landed on a different port, so a genuine 141 VBUS difference (5.2 V → 4.8 V) explains the same delta. Still unresolved. 142 143 ## Power-source behaviour (measured 2026-07-19) 144 145 - **Pulling USB powers the unit off**, even with the GP2 latch set *and* 146 batteries fitted. It does not fall back to battery power. This matches TE's 147 own documentation ("on usb power: the unit will stay powered until you pull 148 the cable"). The likely mechanism is that the power-path handover browns out 149 the RP2350, which resets GP2 and therefore clears the latch. 150 - **Plugging USB in does not power the unit on.** A powered-off unit does not 151 enumerate. Pressing the handle is the only way to *set* the latch. 152 - Consequence for testing: **GP28 can never be read with USB absent if the 153 session began on USB.** Any battery-only measurement must *start* from a 154 battery boot (see the session plan in `power_investigation_session1.md`). 155 156 ### ⚠️ Caveat: the digital probe is unreliable on floating pins 157 158 The pull-up/pull-down digital survey gave **different answers on different runs** 159 for GP20, GP25 and GP26 — an unconnected CMOS input just holds stray charge, so 160 it follows whichever pull was applied last and the timing changes the result. 161 Treat "floating" vs "external pull-up" from that method as provisional unless 162 corroborated. The ADC loading test above is definitive and overrides it for 163 GP26–29. GP25 (not ADC-capable) is therefore still uncertain, and GP20 read 164 externally-low on the second run only — possibly a second switch, or a line whose 165 state depends on whether the unit is running from the handle or from the latch. 166 167 ### ⚠️ Measuring inputs on this board: RP2350-E9 168 169 A naive "internal pull-up vs pull-down" probe reports **every** pin as externally 170 pulled high. That is the RP2350-E9 erratum: with the internal pull-down enabled, 171 a pad that has been high latches high. The reliable method (used above) is to 172 **drive the pin to the opposite state first to clear the latch**, then release it 173 to the internal pull and read: 174 175 - external pull-up test: drive LOW → release with internal pull-DOWN → reads 1 176 - external pull-down test: drive HIGH → release with internal pull-UP → reads 0 177 178 Also note **RP2350 SIO register offsets differ from RP2040**: 179 `GPIO_IN 0x004, GPIO_OUT 0x010, OUT_SET 0x018, OUT_CLR 0x020, OUT_XOR 0x028, 180 GPIO_OE 0x030, OE_SET 0x038, OE_CLR 0x040`. Using the RP2040 offsets silently 181 leaves pins driven. 182 183 ## What GPIO16 is *not* 184 185 GPIO16 is **not** part of the power mechanism — the device latches and holds with 186 GP16 completely idle. It is also **not** the codec MCLK (that is GPIO12, see 187 `nau88l21_pins.md`). Under TE firmware it is a driven, high-rate PIO clock output 188 with no external pull. Still unidentified. 189 190 ## Self-holding boot script 191 192 `scratchpad/device_main.py` is a `main.py` for stock MicroPython that asserts the 193 GP2 latch at boot (before anything else) and then logs GP28/GP26/GP29 plus the 194 whole `GPIO_IN` word from a background thread. Installing it and resetting was 195 verified working: after `machine.reset()` the device came back with 196 `GPIO_OE & 4 == 4` and `GPIO_OUT & 4 == 4`, i.e. it self-held with no 197 intervention. The latch-assert half of that script is reusable; the flash-logging 198 half is **not recommended** (see below). 199 200 ## ⚠️ Do not log to flash across a power-loss event 201 202 The GP28 battery test ended with the unit dropping into the **TING BOOT** 203 bootloader (`2367:0620`, mass storage, `INFO_UF2.TXT` → `UF2 Bootloader v1.0 / 204 Model: EP-2350`) instead of booting MicroPython. The logger was writing and 205 flushing `/plog.csv` every 500 ms precisely while power was being cut, which is a 206 good way to corrupt the littlefs filesystem or leave flash mid-write. 207 208 Both logging strategies tried this session failed, for opposite reasons: 209 210 - **RAM buffer** — erased by the power loss the test was designed to capture. 211 - **Flash file, flushed every 500 ms** — survives power loss in principle, but 212 writing *through* the power loss corrupted the device. 213 214 If a future session needs to capture data across a power transition, prefer: 215 sample into RAM, and **write to flash only once, after the transition, from a 216 still-powered device** — i.e. arrange for the device to survive (battery boot), 217 never for it to die mid-write. 218 219 ## Open questions / next steps 220 221 - **GP28: VBAT/VSYS vs VBUS.** The single unresolved question from this session. 222 See `power_investigation_session1.md` for a concrete, safer test plan. 223 - **`get_vbus`** — probably a digital VBUS-present pin; no candidate found. 224 - **GP25** — not ADC-capable, digital probe gave contradictory results across 225 runs, still unidentified. 226 - ~~**GP20**~~ — **RESOLVED 2026-07-19**: it is the second handle switch 227 (0 = handle at rest / not held). The run-to-run inconsistency was simply the 228 handle being in different positions. See `button_findings.md`, which also maps 229 the three side buttons to GP21 / GP3 / GP1. 230 - Whether the latch also has a hardware-only auto-off (the "20 min" figure is 231 firmware timing, but worth confirming it is not a hardware timeout). 232 - What GPIO16's clock drives (ruled out of the power path entirely). 233 [2026-07-19 09:41:44] tool use: Bash command: ls -la /home/agent/TE_ting/ description: List project files [2026-07-19 09:41:44] tool result: Bash total 13112 drwxrwxr-x 7 agent agent 4096 Jul 19 09:01 . drwx------ 15 agent agent 4096 Jul 19 09:41 .. -rw-rw-r-- 1 agent agent 9477 Jul 18 20:19 audio_codec_bringup_session1.md -rw-rw-r-- 1 agent agent 11274 Jul 18 21:24 audio_codec_bringup_session2.md -rw-rw-r-- 1 agent agent 7837 Jul 18 22:15 audio_codec_bringup_session3.md -rw-rw-r-- 1 agent agent 3639 Jul 19 08:50 button_findings.md drwxrwxr-x 2 agent agent 4096 Jul 18 19:53 .claude -rw-rw-r-- 1 agent agent 2018007 Jul 17 13:44 DS_NAU88L21_DataSheet_EN_Rev2.8.pdf -rw-r--r-- 1 agent agent 1544192 Dec 4 2025 ep-2350_firmware_1_0_8.uf2 -rw-rw-r-- 1 agent agent 663879 Dec 4 2025 ep-2350_firmware_1_0_8.zip -rw-rw-r-- 1 agent agent 8334 Jul 17 17:57 firmware_testing_instructions.md -rw-r--r-- 1 agent agent 1136 Dec 4 2025 fw_download_readme.txt drwxrwxr-x 16 agent agent 4096 Jul 17 14:35 micropython -rw-rw-r-- 1 agent agent 10311 Jul 18 11:23 nau88l21_pins.md drwxrwxr-x 16 agent agent 4096 Jul 18 15:44 Nuvoton-ASoC -rw-rw-r-- 1 agent agent 12219 Jul 17 17:02 pinmapping_findings.md -rw-rw-r-- 1 agent agent 11158 Jul 17 16:11 pinmapping_plan.md -rw-rw-r-- 1 agent agent 12426 Jul 19 09:01 power_hold_findings.md -rw-rw-r-- 1 agent agent 8610 Jul 19 08:26 power_investigation_session1.md drwxrwxr-x 2 agent agent 4096 Jul 17 16:44 __pycache__ -rw-rw-r-- 1 agent agent 6411 Jul 17 15:38 rom_main.py -rw-rw-r-- 1 agent agent 11895 Jul 18 09:32 rom_readme.md -rw-rw-r-- 1 agent agent 7968417 Jul 17 13:52 RP-008373-DS-2-rp2350-datasheet.pdf -rw-rw-r-- 1 agent agent 648704 Jul 18 10:05 RPI_PICO2-20250415-v1.25.0.uf2 drwxrwxr-x 3 agent agent 4096 Jul 19 08:56 scratchpad -rw-rw-r-- 1 agent agent 2320 Jul 17 16:20 scratch_repl.py -rw-rw-r-- 1 agent agent 7588 Jul 17 14:47 TINGDISK_readme.txt -rw-rw-r-- 1 agent agent 2947 Jul 18 22:09 tone_autolock.py -rw-r--r-- 1 agent agent 384044 Jul 18 22:13 tone_capture_2930Hz.wav -rw-rw-r-- 1 agent agent 3510 Jul 19 09:01 volume_knob_findings.md [2026-07-19 09:41:47] thinking: [not recorded in transcript] [2026-07-19 09:41:48] tool use: Bash command: ls -la /home/agent/TE_ting/scratchpad/; sed -n 1,80p /home/agent/TE_ting/button_findings.md description: List scratchpad and read button findings [2026-07-19 09:41:48] tool result: Bash total 108 drwxrwxr-x 3 agent agent 4096 Jul 19 08:56 . drwxrwxr-x 7 agent agent 4096 Jul 19 09:01 .. -rw-rw-r-- 1 agent agent 3033 Jul 19 08:47 btn_monitor.py -rw-rw-r-- 1 agent agent 1242 Jul 19 08:13 device_main.py -rw-rw-r-- 1 agent agent 4383 Jul 18 20:11 device_tone.py -rw-rw-r-- 1 agent agent 5978 Jul 18 22:07 device_tone_slave.py -rw-rw-r-- 1 agent agent 1418 Jul 18 22:04 dma_reset.py -rw-rw-r-- 1 agent agent 3820 Jul 19 08:56 knob_monitor.py -rw-rw-r-- 1 agent agent 329 Jul 18 20:48 lock_test.py -rw-rw-r-- 1 agent agent 1185 Jul 18 11:23 measure_freq.py -rw-rw-r-- 1 agent agent 2828 Jul 18 11:40 play_loopback.py -rw-rw-r-- 1 agent agent 2143 Jul 18 20:46 probe_phase.py drwxrwxr-x 2 agent agent 4096 Jul 18 19:42 __pycache__ -rw-rw-r-- 1 agent agent 1809 Jul 18 11:23 repl.py -rw-rw-r-- 1 agent agent 2764 Jul 18 11:23 rp.py -rw-rw-r-- 1 agent agent 5328 Jul 18 21:55 rx_probe.py -rw-rw-r-- 1 agent agent 1014 Jul 18 11:23 sweep_mclk.py -rw-rw-r-- 1 agent agent 1406 Jul 18 11:23 t1_baseline.py -rw-rw-r-- 1 agent agent 1495 Jul 18 11:23 t2b_adcdat_pull.py -rw-rw-r-- 1 agent agent 1626 Jul 18 11:23 t2c_oe_tri.py -rw-rw-r-- 1 agent agent 1718 Jul 18 11:23 t2_din.py -rw-rw-r-- 1 agent agent 2386 Jul 18 11:23 t3_dout.py -rw-rw-r-- 1 agent agent 2636 Jul 18 20:29 test_d2a_loop.py -rw-rw-r-- 1 agent agent 2214 Jul 18 21:11 tone_autolock.py # EP-2350 button pin map — SOLVED Session date: 2026-07-19. Method: stock MicroPython v1.25.0 (RPI_PICO2) over the raw REPL, all GPIOs configured as inputs with internal pull-ups, streaming a debounced `GPIO_IN` change log (`scratchpad/btn_monitor.py`) while the user pressed buttons in a known order. ## TL;DR | Button | GPIO | Sense | |--------|-----:|-------| | Side button — **top** (nearest handle) | **GP21** | 0 = pressed | | Side button — **middle** | **GP3** | 0 = pressed | | Side button — **bottom** | **GP1** | 0 = pressed | | Handle **fully in** (travel end-stop) | **GP19** | 0 = pressed | | Handle **at rest / not held** | **GP20** | **0 = handle released**, 1 = handle held | All five are simple switches to ground. None have external pull-ups — they read as floating unless the MCU's internal pull-up is enabled, so every button needs `Pin(n, Pin.IN, Pin.PULL_UP)`. ```python from machine import Pin hold = Pin(2, Pin.OUT, value=1) # power latch first, always btn_top = Pin(21, Pin.IN, Pin.PULL_UP) btn_mid = Pin(3, Pin.IN, Pin.PULL_UP) btn_bot = Pin(1, Pin.IN, Pin.PULL_UP) handle_in = Pin(19, Pin.IN, Pin.PULL_UP) # 0 = handle pushed all the way in handle_rest = Pin(20, Pin.IN, Pin.PULL_UP) # 0 = handle out, 1 = handle held ``` ## The handle is a two-stage switch GP19 and GP20 are two separate switches on the same mechanism, and the raw log shows them changing in sequence rather than together: ``` t=46.03s GP19 -> 1 handle starts moving out t=46.20s GP20 -> 0 (+170 ms) handle reaches rest t=52.62s GP20 -> 1 handle starts moving in t=52.94s GP19 -> 0 (+320 ms) handle reaches full travel ``` So there is a dead band in the middle of the travel where **both** read 1 (GP19 released, GP20 released). Useful consequences: - `GP20 == 1` is the earliest possible "user is touching the handle" signal — it fires ~300 ms before GP19 confirms full insertion. - `GP19 == 0` means fully seated, which is what gates the power-on path (see `power_hold_findings.md` — the handle switch supplies power directly until the GP2 latch is asserted). - Neither pin alone tells you the handle position; use the pair. ## Resolves an open question `power_hold_findings.md` listed GP20 as *"read externally-low on one run and floating on another. Possibly a second switch."* It is a second switch, and the inconsistency is explained: GP20's level depends on handle position, and the two earlier probe runs happened with the handle in different states. The same file's "external-drive map of every GPIO" should be read with the caveat that **GP1, GP3 and GP21 were listed as floating** — they are floating only because no button was being pressed during that survey. ## Method notes - A pull-up scan is the right probe for these pins and is **not** affected by the RP2350-E9 erratum, which only corrupts internal-*pull-down* readings. Driving nothing and pulling up is also safe on live hardware. - `GPIO_IN` reads all-zero on a fresh MicroPython boot because RP2350 pads default to input-disabled (`IE=0`). Pins must be instantiated as `Pin` objects before `mem32[SIO+0x004]` means anything. - GP2 must be driven high at the start of any button session, otherwise the unit powers off the moment the handle is released — which is exactly the event you want to observe. - Baseline `GPIO_IN` with the handle in and nothing pressed: `0x3ff7ffff` (only GP19 low). ## Remaining unidentified pins [2026-07-19 09:41:49] tool use: Bash command: sed -n 1,200p /home/agent/TE_ting/pinmapping_findings.md description: Read pin mapping findings [2026-07-19 09:41:49] tool result: Bash # Findings: RP2350 ↔ NAU88L21 pin mapping (EP-2350 "Ting") Session date: 2026-07-17. Method: live read-only register introspection over the serial REPL via a pyserial raw-REPL driver (`scratch_repl.py`), plus static inspection of the firmware image. `mpremote` was **not** used (unreliable here); raw pyserial worked well. ## TL;DR | Signal | GPIO | Confidence | Evidence | |-------------------|-----:|-----------|----------| | **I²C SDA** | **GPIO14** | High | external pull-up + I2C1-capable + I2C1 enabled | | **I²C SCL** | **GPIO15** | High | external pull-up + I2C1-capable + I2C1 enabled | | I²S DIN (ADC, codec→MCU) | GPIO8 | High | PIO SM IN pin; pad is an input | | I²S DOUT (DAC, MCU→codec) | GPIO9 | High | PIO SM OUT pin; driven output | | I²S BCLK | GPIO10 | High (pin) / Med (which-of-10/11) | PIO SM side-set pin | | I²S LRCLK / WS | GPIO11 | High (pin) / Med (which-of-10/11) | PIO SM side-set pin | | MCLK (codec master clock) | GPIO16 | Medium | 2nd PIO SM, high-rate side-set, driven output | The **I²C control bus is hardware I2C1 on GPIO14 (SDA) / GPIO15 (SCL)**. This is the primary answer requested. The NAU88L21's own ACK (0x1B/0x54) could not be captured cleanly on the running firmware (see caveats), but every passive indicator points to this pin pair, and it is the only pin pair on the board that carries the I²C electrical signature. --- ## 1. Environment / important discovery about the firmware - Firmware reports `MicroPython v1.26.0-preview`, `_machine='EP-2350 1.0.8'`, `machine='EP-2350 with RP2350'`. Chip is an **RP2350A** (only GPIO0–29 exist; GPIO30–47 read NULL / `help('modules')` shows `GPIO0..GPIO29`). - **There is no `machine` module** in this custom firmware. Available modules: `rp2, _rp2, uctypes, micropython, teenage, ui, spl, fx, test, vfs, os, ...`. Register access was therefore done with **`uctypes.struct(addr, ...)`** rather than `machine.mem32`. This matters for follow-up work (see §6). - The REPL stays fully interactive while audio runs. Register reads are safe. - There is a factory-test module `test` (`test.chip_id/mcu/audio/adc/...`) and the audio/CODEC bring-up lives in the compiled C modules `ui`/`spl`/`fx`, not Python. ## 2. Primary result — I²C (SDA/SCL) ### Key evidence chain 1. **No GPIO is in I²C function (FUNCSEL==2) at the REPL.** So the CODEC I²C is configured once in C at boot and the pins are then parked in another function — live mux alone does not show it. 2. **Hardware I2C1 is still enabled; I2C0 is not.** Reading the DesignWare I²C peripheral registers: - `I2C1 @ 0x40098000`: `IC_ENABLE=1`, `IC_TAR=0x018`, `IC_CON=0x165`. - `I2C0 @ 0x40090000`: `IC_ENABLE=0`, `IC_TAR=0x055` (0x055 is the *reset default* of `IC_TAR`/`IC_SAR` → I2C0 was effectively never used). → The active control bus is **I2C1**. `IC_TAR=0x18` is the last-addressed device; `0x18` is a classic accelerometer address (the device has an accelerometer, `ui.acc`/shaker) sharing the same control bus. 3. **GPIO14 and GPIO15 uniquely show the I²C electrical signature.** For every pin I compared the pad pull config against the actual line level: - GPIO14, GPIO15: pad has **internal pull-DOWN** (`PADS=0x056`, PDE=1, PUE=0), the pin is **not driven** (`OETOPAD=0`), yet it **reads HIGH** (`GPIO_IN=1`). The only way an undriven, internally-pulled-down pin sits high is an **external pull-up** → these are open-drain bus lines held idle-high. - No other pin has this pattern. (Pins 1/3/19/21 also read high but have *internal* pull-ups and are PIO-driven — not I²C. When I released them to inputs they fell low, i.e. no external pull-up.) 4. **GPIO14/15 are exactly the I2C1 SDA/SCL pins** in the RP2350 fixed function map: pins `(4k+2, 4k+3)` = I2C1 SDA/SCL, so GPIO14 = I2C1 **SDA** (even), GPIO15 = I2C1 **SCL** (odd). This matches the one enabled peripheral (I2C1). 5. **Touching the pair resets the device.** Both times I actively drove/reclocked GPIO14/15 (crude bit-bang, and a hardware-I2C1 reconfigure) the firmware hung and the board watchdog-reset / re-enumerated over USB. That the *pair* is disruptive is consistent with it being a live, shared bus (accelerometer polling collided with my traffic). The board always recovered from flash. Everything converges: **I²C = I2C1, SDA=GPIO14, SCL=GPIO15, with external pull-ups, currently parked in FUNCSEL=PWM(F3) between transactions.** ### Caveats / what is NOT yet proven - I never got a clean **ACK from the NAU88L21 itself (0x1B or 0x54)**, so: - the **CSB strap state** (→ 0x1B vs 0x54) is unknown, and - strictly, I confirmed "the I²C bus and its pins", and that an accelerometer (0x18) lives on it, but not the codec's presence by direct ACK. My active scans were the *only* things that crashed the firmware, precisely because a second master was fighting the running one. A clean scan needs the TE firmware to not be driving the bus concurrently (see §6 — stock MicroPython). - The codec is almost certainly on this same I2C1 bus (I2C0 was never used), but a follow-up scan should verify by reading a known NAU88L21 ID register. ## 3. I²S (audio bus) — bonus, read-only Only two PIO state machines are enabled. Decoding their `PINCTRL`: - **I²S data/clocks** — SM0 of the PIO register block at `0x50200000`, `CLKDIV≈5.0`, `PINCTRL`: `OUT_BASE=9 (cnt1)`, `IN_BASE=8`, `SIDESET_BASE=10 (cnt2)`. Cross-checked against the actual pad direction (`GPIOn_STATUS.OETOPAD` / `INFROMPAD`): - **GPIO8** = **DIN** (input; ADC/mic data codec→MCU) — pad is an input. - **GPIO9** = **DOUT** (output; DAC data MCU→codec) — driven output. - **GPIO10 / GPIO11** = **BCLK** and **LRCLK/WS** (the two side-set clocks; both driven outputs). Which is which is not yet disambiguated (needs the PIO program / a scope). Convention makes GPIO10=BCLK, GPIO11=LRCLK likely. - **MCLK candidate** — SM0 of the PIO block at `0x50300000`, `CLKDIV≈4.0`, side-set on **GPIO16** with `SIDE_EN` (a single high-rate clock output). GPIO16 is a driven output. This looks like the codec **MCLK**. ### An unresolved labeling quirk (does not change the GPIO numbers) The pins carrying I²S (GPIO8–11) read `FUNCSEL=6` (=PIO1) and MCLK (GPIO16) reads `FUNCSEL=7` (=PIO2), yet the *matching, enabled* state-machine configs sit in the register blocks one lower (0x50200000 "PIO0" and 0x50300000 "PIO1" respectively). I could not reconcile this off-by-one purely from registers. It does **not** affect the pin assignments above (those are anchored on actual pad direction + the SM's own PINCTRL), only the PIO-instance *name*. Worth a glance under stock firmware where `rp2.PIO`/`StateMachine` introspection is easy. ## 4. Full active-pin snapshot (post-reset, read-only) FUNCSEL, pad-driven (OEtoPAD), input level, pad reg, internal pulls: ``` gpio fn OEpad IN pad PUE PDE note 0 SIO 1/0* - 056 0 1 (dynamic: LED/switch) 1 PIO0 0 1 05a 1 0 internal pull-up (PIO-driven) 2 PIO0 1 1 056 0 1 driven high 3 PIO0 0 1 05a 1 0 internal pull-up 4 SIO 1 0 056 0 1 5 SIO 1 0 056 0 1 6 SIO 1 0 056 0 1 8 PIO1 0 0 05a 1 0 I2S DIN (input) 9 PIO1 1 0 056 0 1 I2S DOUT (output) 10 PIO1 1 - 056 0 1 I2S BCLK/LRCLK (side-set) 11 PIO1 1 - 056 0 1 I2S BCLK/LRCLK (side-set) 14 PWM 0 1 056 0 1 *** I2C1 SDA (external pull-up) *** 15 PWM 0 1 056 0 1 *** I2C1 SCL (external pull-up) *** 16 PIO2 1 0 056 0 1 MCLK candidate (side-set, clkdiv 4) 17 SIO 1 0 056 0 1 18 SIO 1 0 056 0 1 19 PIO0 0 1 05a 1 0 internal pull-up 20 PIO0 0 0 05a 1 0 21 PIO0 0 1 05a 1 0 internal pull-up 24 SIO 1 0 056 0 1 25 PIO0 1 0 056 0 1 (likely status LED) ``` `pad 0x056` = PDE(pull-down), `0x05a` = PUE(pull-up); both have IE=1, SchmittEn, drive=4mA. I2C0 disabled; I2C1 enabled, TAR=0x18. ## 5. Reference register locations used (RP2350, verified vs datasheet) ``` IO_BANK0 0x40028000 GPIOn: STATUS @ +8n (OETOPAD=bit13, OUTTOPAD=bit9, INFROMPAD=bit17) CTRL @ +8n+4 (FUNCSEL = CTRL[4:0]) PADS_BANK0 0x40038000 GPIOn pad @ +4+4n (IE=b6, OD=b7, DRV=b5:4, PUE=b3, PDE=b2, SCH=b1) SIO 0xd0000000 GPIO_IN +0x004, GPIO_OUT +0x010, GPIO_OE +0x030 (SET/CLR +8/+0x10) I2C0/I2C1 0x40090000 / 0x40098000 IC_CON +0x00, IC_TAR +0x04, IC_DATA_CMD +0x10, IC_ENABLE +0x6c, IC_ENABLE_STATUS +0x9c, IC_TX_ABRT_SOURCE +0x80 PIO0/1/2 0x50200000 / 0x50300000 / 0x50400000 CTRL +0, SMx PINCTRL @ +0xdc+0x18*x FUNCSEL: 0 SPI, 1 UART, 2 I2C, 3 PWM, 4 SIO, 5 PIO0, 6 PIO1, 7 PIO2, 31 NULL ``` ## 6. Suggested follow-up tests (recommended: stock MicroPython) The cleanest confirmation is to **temporarily flash stock MicroPython for the Pico 2 / RP2350** (board `RPI_PICO2`), which restores the `machine` module and — crucially — means **no competing firmware is driving the I²C bus**, so a scan won't cause contention. Keep `ep-2350_firmware_1_0_8.uf2` handy to restore the TE firmware afterward (drag-and-drop over BOOTSEL). All tests below are quick. **T1 — Confirm I²C pins + enumerate devices (settles SDA/SCL + finds codec):** ```python from machine import Pin, I2C, SoftI2C # hardware I2C1 is SDA=GP14, SCL=GP15: i2c = I2C(1, sda=Pin(14), scl=Pin(15), freq=100_000) print([hex(a) for a in i2c.scan()]) # expect 0x1b or 0x54 (codec) AND 0x18 (accel) # also try SoftI2C in case of any HW-mux surprise: s = SoftI2C(scl=Pin(15), sda=Pin(14), freq=100_000) print([hex(a) for a in s.scan()]) ``` Success = the scan returns the NAU88L21 address → proves GPIO14/15 and reveals the CSB strap (0x1B = CSB0, 0x54 = CSB1). **T2 — Positively identify the NAU88L21 (not just "something ACKed"):** Read a NAU88L21 ID/reset register over I²C (16-bit register address, 16-bit data, big-endian per its datasheet), e.g. read the software-reset/device-ID region: ```python addr = 0x1b # or whatever T1 found i2c.writeto(addr, bytes([0x00, 0x00])) # set register pointer to 0x0000 print(i2c.readfrom(addr, 2).hex()) # read back 16-bit reg value ``` Compare against the NAU88L21 datasheet's ID/default value to be 100% sure it is the codec and not another device. **T3 — Disambiguate BCLK vs LRCLK and confirm MCLK (GPIO16):** Under stock firmware you can't easily see the *original* config, but you can: - reason from I²S timing: LRCLK = sample rate (e.g. 48 kHz), BCLK = LRCLK × bits × channels; MCLK (GP16) is much faster (256×/384× fs). A logic-analyzer/scope on GP10, GP11, GP16 settles it instantly. [2026-07-19 09:41:55] thinking: [not recorded in transcript] [2026-07-19 09:41:57] tool use: Bash command: cat /home/agent/TE_ting/scratchpad/rp.py; echo ====; cat /home/agent/TE_ting/scratchpad/repl.py; echo ====; sed -n 80,200p /home/agent/TE_ting/button_findings.md description: Read REPL driver helpers [2026-07-19 09:41:57] tool result: Bash #!/usr/bin/env python3 """Robust raw-REPL exec helper for the EP-2350 over /dev/ttyACM0. Enters raw REPL, sends code + ctrl-D, and parses the framed reply: b"OK" b"\\x04" b"\\x04" b">" Reads by scanning for the two \\x04 terminators rather than relying on endswith(), which was racy when output arrived in multiple chunks. """ import sys, time, serial PORT = "/dev/ttyACM0" BAUD = 115200 def _drain_until(ser, marker, timeout): marker = marker if isinstance(marker, bytes) else marker.encode() buf = bytearray() deadline = time.time() + timeout while time.time() < deadline: n = ser.in_waiting if n: buf += ser.read(n) i = buf.find(marker) if i != -1: return bytes(buf[:i]), bytes(buf[i + len(marker):]) else: time.sleep(0.005) raise TimeoutError("marker %r not seen; got %r" % (marker, bytes(buf[-200:]))) def run(code, timeout=15.0): if isinstance(code, str): code = code.encode() with serial.Serial(PORT, BAUD, timeout=0.1) as ser: ser.write(b"\r\x03\x03") # interrupt any running program time.sleep(0.2) ser.reset_input_buffer() ser.write(b"\x01") # ctrl-A -> raw REPL _drain_until(ser, b"raw REPL; CTRL-B to exit\r\n>", timeout=3.0) ser.reset_input_buffer() ser.write(code) ser.write(b"\x04") # ctrl-D -> execute # device echoes "OK" once accepted _, rest = _drain_until(ser, b"OK", timeout=5.0) # stdout up to first \x04 stdout, rest = _drain_until_buffered(ser, rest, b"\x04", timeout) stderr, rest = _drain_until_buffered(ser, rest, b"\x04", timeout) ser.write(b"\x02") # ctrl-B -> friendly REPL return stdout.decode(errors="replace"), stderr.decode(errors="replace") def _drain_until_buffered(ser, pre, marker, timeout): """Like _drain_until but seeds with already-read bytes `pre`.""" buf = bytearray(pre) i = buf.find(marker) if i != -1: return bytes(buf[:i]), bytes(buf[i + len(marker):]) deadline = time.time() + timeout while time.time() < deadline: n = ser.in_waiting if n: buf += ser.read(n) i = buf.find(marker) if i != -1: return bytes(buf[:i]), bytes(buf[i + len(marker):]) else: time.sleep(0.005) raise TimeoutError("marker %r not seen; got %r" % (marker, bytes(buf[-200:]))) if __name__ == "__main__": src = sys.stdin.read() if len(sys.argv) < 2 else open(sys.argv[1]).read() o, e = run(src) sys.stdout.write(o) if e.strip(): sys.stderr.write("\n--- STDERR ---\n" + e) ==== #!/usr/bin/env python3 """Reliable raw-REPL exec helper for the EP-2350 over /dev/ttyACM0.""" import sys, time, serial PORT = "/dev/ttyACM0" BAUD = 115200 def _read_until(ser, ending, timeout=5.0): ending = ending if isinstance(ending, bytes) else ending.encode() buf = bytearray() deadline = time.time() + timeout while time.time() < deadline: n = ser.in_waiting if n: buf += ser.read(n) if buf.endswith(ending) or ending in buf: return bytes(buf), True deadline = time.time() + timeout else: time.sleep(0.005) return bytes(buf), False def run(code, timeout=10.0): if isinstance(code, str): code = code.encode() with serial.Serial(PORT, BAUD, timeout=0.1) as ser: ser.write(b"\r\x03\x03") # interrupt time.sleep(0.2) ser.reset_input_buffer() ser.write(b"\x01") # ctrl-A -> raw REPL _read_until(ser, b"raw REPL; CTRL-B to exit\r\n>", timeout=2.0) ser.reset_input_buffer() ser.write(code) ser.write(b"\x04") # ctrl-D -> execute _read_until(ser, b"OK", timeout=3.0) out, _ = _read_until(ser, b"\x04", timeout=timeout) err, _ = _read_until(ser, b"\x04", timeout=timeout) ser.write(b"\x02") # ctrl-B -> back to normal stdout = out[:-1] if out.endswith(b"\x04") else out stderr = err[:-1] if err.endswith(b"\x04") else err return stdout.decode(errors="replace"), stderr.decode(errors="replace") if __name__ == "__main__": src = sys.stdin.read() if len(sys.argv) < 2 else open(sys.argv[1]).read() o, e = run(src) sys.stdout.write(o) if e.strip(): sys.stderr.write("\n--- STDERR ---\n" + e) ==== Unchanged by this session: GP16 (PIO clock output under TE firmware), GP25, and the `get_vbus` digital sense line. No button accounts for any of them. [2026-07-19 09:42:05] thinking: [not recorded in transcript] [2026-07-19 09:42:07] tool use: Bash command: ls /dev/ttyACM* /dev/video* 2>&1; python3 scratchpad/rp.py <<'EOF' import sys, machine print(sys.implementation) from machine import Pin h=Pin(2,Pin.OUT,value=1) print("latched") EOF description: Check device and assert power latch [2026-07-19 09:42:07] tool result: Bash /dev/ttyACM0 /dev/video0 /dev/video1 /dev/video19 /dev/video20 /dev/video21 /dev/video22 /dev/video23 /dev/video24 /dev/video25 /dev/video26 /dev/video27 /dev/video28 /dev/video29 /dev/video30 /dev/video31 /dev/video32 /dev/video33 /dev/video34 /dev/video35 (name='micropython', version=(1, 25, 0, ''), _machine='Raspberry Pi Pico2 with RP2350', _mpy=7942, _build='RPI_PICO2') latched [2026-07-19 09:42:10] thinking: [not recorded in transcript] [2026-07-19 09:42:12] tool use: Bash command: cd /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad && ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2" -frames 1 baseline.jpg 2>&1 | tail -2 description: Capture baseline photo [2026-07-19 09:42:23] tool result: Bash [out#0/image2 @ 0x5555e7904b90] video:44KiB audio:0KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: unknown frame= 1 fps=0.0 q=5.9 Lsize=N/A time=00:00:00.10 bitrate=N/A speed=0.991x Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:42:25] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/baseline.jpg [2026-07-19 09:42:25] tool result: Read [image: image/jpeg] [2026-07-19 09:42:34] thinking: [not recorded in transcript] [2026-07-19 09:42:35] agent: All 8 LEDs visible and dimly lit. Candidate pins from the TE-firmware snapshot are GP0, 4, 5, 6, 17, 18, 24, 25 — exactly 8. Testing the hypothesis that they're active-low (dim glow = pad default pull-down leaking through them). [2026-07-19 09:42:39] tool use: Write file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/shot.sh content: #!/bin/bash # usage: shot.sh name D=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 \ -vf "hflip,vflip,transpose=2,crop=200:450:490:100" -frames 1 "$D/$1.jpg" 2>/dev/null echo "$D/$1.jpg" [2026-07-19 09:42:39] tool result: Write File created successfully at: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/shot.sh (file state is current in your context — no need to Read it back) [2026-07-19 09:42:44] tool use: Bash command: chmod +x /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/shot.sh && python3 scratchpad/rp.py <<'EOF' from machine import Pin h=Pin(2,Pin.OUT,value=1) C=[0,4,5,6,17,18,24,25] ps=[Pin(n,Pin.OUT,value=1) for n in C] print("all high") EOF /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/shot.sh allhigh description: Drive candidate pins high and photograph [2026-07-19 09:42:51] tool result: Bash all high /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/allhigh.jpg [2026-07-19 09:42:53] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/allhigh.jpg [2026-07-19 09:42:53] tool result: Read [image: image/jpeg] [2026-07-19 09:43:00] thinking: [not recorded in transcript] [2026-07-19 09:43:00] agent: Active-**high** — all 8 now bright. Now isolating one pin at a time. [2026-07-19 09:43:06] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad for p in 0 4 5 6 17 18 24 25; do python3 /home/agent/TE_ting/scratchpad/rp.py </dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,17,18,24,25]: Pin(n,Pin.OUT,value=1 if n==$p else 0) EOF $S/shot.sh only_$p >/dev/null done echo done description: Photograph each candidate pin driven high alone [2026-07-19 09:43:23] tool result: Bash done [2026-07-19 09:43:27] tool use: Bash command: cd /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad && ffmpeg -y -i only_0.jpg -i only_4.jpg -i only_5.jpg -i only_6.jpg -i only_17.jpg -i only_18.jpg -i only_24.jpg -i only_25.jpg -filter_complex "hstack=inputs=8" grid.jpg 2>&1|tail -1 description: Stack per-pin photos into one strip [2026-07-19 09:43:31] tool result: Bash frame= 1 fps=0.0 q=5.9 Lsize=N/A time=00:00:00.04 bitrate=N/A speed=2.03x Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:43:35] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid.jpg [2026-07-19 09:43:35] tool result: Read [image: image/jpeg] [2026-07-19 09:43:58] thinking: [not recorded in transcript] [2026-07-19 09:43:59] agent: Clean 1:1 mapping for 7 of 8. The top red LED stays lit in every frame, so let me isolate it. [2026-07-19 09:44:07] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad py(){ python3 /home/agent/TE_ting/scratchpad/rp.py >/dev/null; } # A: all candidates high-Z inputs (no pulls) python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,17,18,24,25]: Pin(n,Pin.IN,None) EOF $S/shot.sh A_hiZ >/dev/null # B: all candidates driven low python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,17,18,24,25]: Pin(n,Pin.OUT,value=0) EOF $S/shot.sh B_alllow >/dev/null # C: 25 high, rest hi-Z python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,17,18,24]: Pin(n,Pin.IN,None) Pin(25,Pin.OUT,value=1) EOF $S/shot.sh C_25hi >/dev/null cd $S && ffmpeg -y -i A_hiZ.jpg -i B_alllow.jpg -i C_25hi.jpg -filter_complex hstack=inputs=3 grid2.jpg 2>&1|tail -1 description: Compare hi-Z, all-low, and GP25-only states [2026-07-19 09:44:14] tool result: Bash frame= 1 fps=0.0 q=4.8 Lsize=N/A time=00:00:00.04 bitrate=N/A speed=5.57x Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:44:17] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid2.jpg [2026-07-19 09:44:17] tool result: Read [image: image/jpeg] [2026-07-19 09:44:34] thinking: [not recorded in transcript] [2026-07-19 09:44:35] agent: Camera auto-exposure differs per shot; the key result is GP25 changes nothing. Sweeping the remaining unassigned pins for the 4th red. [2026-07-19 09:44:40] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad for p in 7 12 13 16 22 23 26 27; do python3 /home/agent/TE_ting/scratchpad/rp.py </dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,17,18,24,25]: Pin(n,Pin.OUT,value=0) Pin($p,Pin.OUT,value=1) EOF $S/shot.sh hi_$p >/dev/null done for p in 7 12 13 16 22 23 26 27; do python3 /home/agent/TE_ting/scratchpad/rp.py </dev/null from machine import Pin Pin(2,Pin.OUT,value=1) Pin($p,Pin.OUT,value=0) EOF $S/shot.sh lo_$p >/dev/null done cd $S && ffmpeg -y -i hi_7.jpg -i hi_12.jpg -i hi_13.jpg -i hi_16.jpg -i hi_22.jpg -i hi_23.jpg -i hi_26.jpg -i hi_27.jpg -filter_complex hstack=inputs=8 grid_hi.jpg 2>/dev/null; ffmpeg -y -i lo_7.jpg -i lo_12.jpg -i lo_13.jpg -i lo_16.jpg -i lo_22.jpg -i lo_23.jpg -i lo_26.jpg -i lo_27.jpg -filter_complex hstack=inputs=8 grid_lo.jpg 2>/dev/null; echo ok description: Sweep remaining pins high and low [2026-07-19 09:45:41] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:45:44] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_hi.jpg [2026-07-19 09:45:44] tool result: Read [image: image/jpeg] [2026-07-19 09:45:45] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_lo.jpg [2026-07-19 09:45:45] tool result: Read [image: image/jpeg] [2026-07-19 09:46:15] thinking: [not recorded in transcript] [2026-07-19 09:46:15] agent: GP16 is the missing one — driving it low turned the top red off. Confirming independence and the boot-default dim state. [2026-07-19 09:46:24] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad LEDS="0,4,5,6,16,17,18,24" run(){ python3 /home/agent/TE_ting/scratchpad/rp.py >/dev/null; } # D: only GP16 high, all other LED pins low python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=(n==16)) EOF $S/shot.sh D_16only >/dev/null # E: GP16 low, GP0 high python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=(n==0)) EOF $S/shot.sh E_0only >/dev/null # F: all 8 LED pins high python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=1) EOF $S/shot.sh F_all8 >/dev/null # G: all 8 low python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=0) EOF $S/shot.sh G_all0 >/dev/null cd $S && ffmpeg -y -i D_16only.jpg -i E_0only.jpg -i F_all8.jpg -i G_all0.jpg -filter_complex hstack=inputs=4 grid3.jpg 2>/dev/null; echo ok description: Verify GP16 and independence [2026-07-19 09:47:53] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:47:55] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid3.jpg [2026-07-19 09:47:55] tool result: Read [image: image/jpeg] [2026-07-19 09:48:28] thinking: [not recorded in transcript] [2026-07-19 09:48:28] agent: Confirmed. Now testing the "dim" explanation (internal pull-ups left from the button session) and PWM dimming. [2026-07-19 09:48:34] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.IN,Pin.PULL_UP) EOF $S/shot.sh H_pullup >/dev/null python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.IN,None) EOF $S/shot.sh I_hiz >/dev/null # PWM ramp across the 8 python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' from machine import Pin, PWM Pin(2,Pin.OUT,value=1) L=[0,4,5,6,16,17,18,24] duty=[164,655,2621,10485,164,655,2621,10485] ps=[] for n,d in zip(L,duty): p=PWM(Pin(n)); p.freq(1000); p.duty_u16(d); ps.append(p) print("pwm ok") EOF $S/shot.sh J_pwm >/dev/null cd $S && ffmpeg -y -i H_pullup.jpg -i I_hiz.jpg -i J_pwm.jpg -filter_complex hstack=inputs=3 grid4.jpg 2>/dev/null; echo ok description: Test pull-up glow, hi-Z, and PWM dimming [2026-07-19 09:48:41] tool result: Bash pwm ok ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:48:44] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid4.jpg [2026-07-19 09:48:44] tool result: Read [image: image/jpeg] [2026-07-19 09:49:03] thinking: [not recorded in transcript] [2026-07-19 09:49:08] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=(n in (0,5,16,18))) EOF $S/shot.sh K_0_5_16_18 >/dev/null python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=(n in (4,6,17,24))) EOF $S/shot.sh L_4_6_17_24 >/dev/null # clean hi-Z after being driven low python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin import time Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=0) time.sleep(1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.IN,None) EOF $S/shot.sh M_hiz_after_low >/dev/null cd $S && ffmpeg -y -i K_0_5_16_18.jpg -i L_4_6_17_24.jpg -i M_hiz_after_low.jpg -filter_complex hstack=inputs=3 grid5.jpg 2>/dev/null; echo ok description: Verify positional order with alternating patterns [2026-07-19 09:55:22] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:55:25] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid5.jpg [2026-07-19 09:55:25] tool result: Read [image: image/jpeg] [2026-07-19 09:55:34] thinking: [not recorded in transcript] [2026-07-19 09:55:39] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad cap(){ ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2,crop=120:200:500:290,eq=brightness=-0.25" -frames 1 $S/$1.jpg 2>/dev/null; } for p in 0 4 5 6; do python3 /home/agent/TE_ting/scratchpad/rp.py </dev/null from machine import Pin, PWM Pin(2,Pin.OUT,value=1) for n in [16,17,18,24]: Pin(n,Pin.OUT,value=0) for n in [0,4,5,6]: p=PWM(Pin(n)); p.freq(1000); p.duty_u16(1200 if n==$p else 0) EOF cap w_$p done cd $S && ffmpeg -y -i w_0.jpg -i w_4.jpg -i w_5.jpg -i w_6.jpg -filter_complex hstack=inputs=4 grid_w.jpg 2>/dev/null; echo ok description: Low-duty per-white-LED shots to avoid bloom [2026-07-19 09:56:59] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:57:02] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_w.jpg [2026-07-19 09:57:02] tool result: Read [image: image/jpeg] [2026-07-19 09:57:12] thinking: [not recorded in transcript] [2026-07-19 09:57:16] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad cap(){ ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2,crop=140:400:495:110,eq=brightness=-0.30" -frames 1 $S/$1.jpg 2>/dev/null; } for p in 0 4 5 6 16 17 18 24; do python3 /home/agent/TE_ting/scratchpad/rp.py </dev/null from machine import Pin, PWM Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: q=PWM(Pin(n)); q.freq(1000); q.duty_u16(1500 if n==$p else 0) EOF cap f_$p done cd $S && ffmpeg -y -i f_0.jpg -i f_4.jpg -i f_5.jpg -i f_6.jpg -i f_16.jpg -i f_17.jpg -i f_18.jpg -i f_24.jpg -filter_complex hstack=inputs=8 grid_final.jpg 2>/dev/null; echo ok description: Definitive low-duty per-LED map, full column [2026-07-19 09:57:36] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 09:57:38] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_final.jpg [2026-07-19 09:57:38] tool result: Read [image: image/jpeg] [2026-07-19 09:57:49] thinking: [not recorded in transcript] [2026-07-19 09:57:50] agent: Camera returns a stale first frame — that can shift a whole sweep. Redoing with settle time and discarding early frames. [2026-07-19 09:57:55] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad cap(){ ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2,crop=140:400:495:110,eq=brightness=-0.30" -vsync 0 -frames:v 15 $S/tmp_%02d.jpg 2>/dev/null; cp $S/tmp_15.jpg $S/$1.jpg; rm -f $S/tmp_*.jpg; } for p in 0 4 5 6 16 17 18 24; do python3 /home/agent/TE_ting/scratchpad/rp.py </dev/null from machine import Pin, PWM Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: q=PWM(Pin(n)); q.freq(1000); q.duty_u16(1500 if n==$p else 0) EOF cap g_$p done cd $S && ffmpeg -y -i g_0.jpg -i g_4.jpg -i g_5.jpg -i g_6.jpg -i g_16.jpg -i g_17.jpg -i g_18.jpg -i g_24.jpg -filter_complex hstack=inputs=8 grid_final2.jpg 2>/dev/null; echo ok description: Re-run per-LED map discarding stale camera frames [2026-07-19 10:00:20] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 10:00:23] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_final2.jpg [2026-07-19 10:00:23] tool result: Read [image: image/jpeg] [2026-07-19 10:00:39] thinking: [not recorded in transcript] [2026-07-19 10:00:39] agent: PWM slice collision spotted (GP0 and GP16 are both PWM0-A). Final confirmation with plain digital drive. [2026-07-19 10:00:44] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad cap(){ ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2,crop=140:400:495:110,eq=brightness=-0.45" -vsync 0 -frames:v 15 $S/t_%02d.jpg 2>/dev/null; cp $S/t_15.jpg $S/$1.jpg; rm -f $S/t_*.jpg; } for p in 0 4 5 6 16 17 18 24; do python3 /home/agent/TE_ting/scratchpad/rp.py </dev/null from machine import Pin Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=(n==$p)) EOF cap d_$p done cd $S && ffmpeg -y -i d_0.jpg -i d_4.jpg -i d_5.jpg -i d_6.jpg -i d_16.jpg -i d_17.jpg -i d_18.jpg -i d_24.jpg -filter_complex hstack=inputs=8 grid_dig.jpg 2>/dev/null; echo ok description: Digital single-LED map with dark exposure [2026-07-19 10:04:52] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 10:04:55] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_dig.jpg [2026-07-19 10:04:55] tool result: Read [image: image/jpeg] [2026-07-19 10:05:02] thinking: [not recorded in transcript] [2026-07-19 10:05:09] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad cap(){ ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2,crop=140:400:495:110,eq=brightness=-0.30" -vsync 0 -frames:v 15 $S/t_%02d.jpg 2>/dev/null; cp $S/t_15.jpg $S/$1.jpg; rm -f $S/t_*.jpg; } for p in 0 4 5 6 16 17 18 24; do python3 /home/agent/TE_ting/scratchpad/rp.py </dev/null from machine import Pin, PWM Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=0) q=PWM(Pin($p)); q.freq(1000); q.duty_u16(1200) EOF cap e_$p done cd $S && ffmpeg -y -i e_0.jpg -i e_4.jpg -i e_5.jpg -i e_6.jpg -i e_16.jpg -i e_17.jpg -i e_18.jpg -i e_24.jpg -filter_complex hstack=inputs=8 grid_e.jpg 2>/dev/null; echo ok description: Per-LED map, PWM on target pin only [2026-07-19 10:05:35] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 10:05:38] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_e.jpg [2026-07-19 10:05:38] tool result: Read [image: image/jpeg] [2026-07-19 10:06:00] thinking: [not recorded in transcript] [2026-07-19 10:06:00] agent: Clean and unambiguous. Final cross-check with a two-of-each pattern: [2026-07-19 10:06:08] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad cap(){ ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2,crop=140:400:495:110,eq=brightness=-0.30" -vsync 0 -frames:v 15 $S/t_%02d.jpg 2>/dev/null; cp $S/t_15.jpg $S/$1.jpg; rm -f $S/t_*.jpg; } # expect: bottom two of each column (whites 3&4 = GP4,GP5 ; reds 3&4 = GP18,GP17) python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin, PWM Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=0) for n in [4,5,17,18]: q=PWM(Pin(n)); q.freq(1000); q.duty_u16(1200) EOF cap X_bottom2 # expect: top two of each column (whites 1&2 = GP0,GP6 ; reds 1&2 = GP16,GP24) python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' >/dev/null from machine import Pin, PWM Pin(2,Pin.OUT,value=1) for n in [0,4,5,6,16,17,18,24]: Pin(n,Pin.OUT,value=0) for n in [0,6,16,24]: q=PWM(Pin(n)); q.freq(1000); q.duty_u16(1200) EOF cap Y_top2 cd $S && ffmpeg -y -i X_bottom2.jpg -i Y_top2.jpg -filter_complex hstack=inputs=2 grid_xy.jpg 2>/dev/null; echo ok description: Cross-check top/bottom pair patterns [2026-07-19 10:15:03] tool result: Bash ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 10:15:06] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_xy.jpg [2026-07-19 10:15:06] tool result: Read [image: image/jpeg] [2026-07-19 10:15:14] thinking: [not recorded in transcript] [2026-07-19 10:15:14] agent: Map confirmed. One last check — pad drive strength for max brightness: [2026-07-19 10:15:22] tool use: Bash command: S=/tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad cap(){ ffmpeg -y -f v4l2 -video_size 1280x720 -i /dev/video0 -vf "hflip,vflip,transpose=2,crop=140:400:495:110,eq=brightness=-0.55" -vsync 0 -frames:v 15 $S/t_%02d.jpg 2>/dev/null; cp $S/t_15.jpg $S/$1.jpg; rm -f $S/t_*.jpg; } python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' from machine import Pin, mem32 PADS=0x40038000 L=[0,4,5,6,16,17,18,24] Pin(2,Pin.OUT,value=1) for n in L: Pin(n,Pin.OUT,value=1) print("pad drive bits (2b):", [(mem32[PADS+4+4*n]>>4)&3 for n in L]) EOF cap Z_drive_default python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' from machine import Pin, mem32 PADS=0x40038000 for n in [0,4,5,6,16,17,18,24]: a=PADS+4+4*n; mem32[a]=(mem32[a]&~0x30)|0x30 # 12 mA print("set 12mA") EOF cap Z_drive_12ma cd $S && ffmpeg -y -i Z_drive_default.jpg -i Z_drive_12ma.jpg -filter_complex hstack=inputs=2 grid_z.jpg 2>/dev/null; echo ok description: Compare default vs 12mA pad drive brightness [2026-07-19 10:15:30] tool result: Bash pad drive bits (2b): [1, 1, 1, 1, 1, 1, 1, 1] set 12mA ok Shell cwd was reset to /home/agent/TE_ting [2026-07-19 10:15:32] tool use: Read file_path: /tmp/claude-1001/-home-agent-TE-ting/c0c8c8a0-e237-4540-bae3-488162b80dd9/scratchpad/grid_z.jpg [2026-07-19 10:15:32] tool result: Read [image: image/jpeg] [2026-07-19 10:15:38] thinking: [not recorded in transcript] [2026-07-19 10:15:41] tool use: Bash command: python3 /home/agent/TE_ting/scratchpad/rp.py <<'EOF' from machine import Pin, mem32 import time PADS=0x40038000 L=[0,6,4,5,16,24,18,17] Pin(2,Pin.OUT,value=1) for n in L: a=PADS+4+4*n; mem32[a]=(mem32[a]&~0x30)|0x10 # back to 4 mA ps=[Pin(n,Pin.OUT,value=0) for n in L] # quick chase to prove ordering interactively for _ in range(3): for p in ps: p.value(1); time.sleep_ms(60); p.value(0) print("drive bits now:", [(mem32[PADS+4+4*n]>>4)&3 for n in L], "all off") EOF description: Restore drive strength, run chase, leave LEDs off [2026-07-19 10:15:42] tool result: Bash drive bits now: [1, 1, 1, 1, 1, 1, 1, 1] all off [2026-07-19 10:15:45] agent: Now writing up the findings. [2026-07-19 10:16:18] tool use: Write file_path: /home/agent/TE_ting/led_findings.md content: # EP-2350 LED pin map — SOLVED Session date: 2026-07-19. Method: stock MicroPython v1.25.0 (RPI_PICO2) over the raw REPL (`scratchpad/rp.py`), driving candidate GPIOs one at a time while a USB camera photographed the LED bar. Photos under `scratchpad/` (`grid_e.jpg` is the decisive one-LED-at-a-time strip). ## TL;DR Eight LEDs, **eight dedicated GPIOs, one per LED, active HIGH**. No matrix, no charlieplexing, no shift register, no enable line. | Position (top → bottom) | Red column | White column | |---|---:|---:| | 1 (nearest handle) | **GP16** | **GP0** | | 2 | **GP24** | **GP6** | | 3 | **GP18** | **GP4** | | 4 | **GP17** | **GP5** | Note the columns are **not** in GPIO order — GP6 sits above GP4/GP5 in the white column, and the red column runs 16, 24, 18, 17. ```python from machine import Pin Pin(2, Pin.OUT, value=1) # power latch first, always RED = [16, 24, 18, 17] # top -> bottom WHITE = [0, 6, 4, 5] # top -> bottom leds = [Pin(n, Pin.OUT, value=0) for n in RED + WHITE] leds[0].value(1) # top red on ``` ## Control scheme - **Drive HIGH = on, LOW = off.** LED anode on the GPIO, cathode to ground through a series resistor (each LED has its own). - **Full brightness is just a digital `1`.** Pad drive strength makes no difference: setting `PADS_BANK0` DRIVE from the default 4 mA to 12 mA on all eight produced **no visible change**, so the series resistors set the current, not the pad. Don't bother raising drive strength. - **Dimming is plain PWM** and works well. `PWM(Pin(n)); freq(1000); duty_u16(...)` gave a clean, monotonic brightness range; duty ≈ 1200/65535 is a comfortable "dim indicator" level and is what most of the photos above use. - **High-Z (`Pin.IN`, no pull) = fully off.** Verified after first driving the pins low, to defeat pad retention. ### ⚠️ PWM gotcha: GP0 and GP16 share a PWM slice/channel Configuring PWM on **GP16** and on **GP0** targets the *same* slice+channel, so the second `duty_u16()` silently overrides the first, and both pins output the same waveform. This bit the first mapping run: a sweep that put *all eight* pins into PWM function made the top white LED (GP0) follow GP16. Consequences: - **Top red and top white cannot be PWM-dimmed independently.** Use PWM on one and plain on/off (SIO) on the other, or bit-bang one in software. - The mirroring only appears when a pin's function is actually muxed to PWM. If GP0 is left as a normal `Pin.OUT`, PWM on GP16 does not affect it. ## Why all 8 were glowing dimly at session start Not a hardware feature — it was **leftover state from the button/knob sessions**, which configure every GPIO as `Pin.IN, Pin.PULL_UP`. The internal pull-up (~50–80 kΩ) sources roughly 40 µA into each LED, which is plenty for a visible dim glow. Reproduced exactly: setting the eight pins back to `Pin.IN, Pin.PULL_UP` recreates the original dim look (`scratchpad/H_pullup.jpg` vs `baseline.jpg`); `Pin.IN, None` after a driven low gives full off. So a "dim standby glow" is available for free without PWM if you ever want it — just enable the internal pull-up instead of driving the pin. ## Evidence 1. **Candidate set from the TE-firmware pin snapshot** (`pinmapping_findings.md` §4): the unexplained SIO-driven pins were GP0, 4, 5, 6, 17, 18, 24, 25 — exactly eight, which looked like a perfect fit. 2. **All eight driven high → all LEDs bright**, confirming active-high. 3. **One-at-a-time sweep** gave a clean 1:1 mapping for seven of them, but **GP25 lit nothing**, and the top red stayed lit no matter what. So GP25 is *not* an LED and the candidate set was wrong by one. 4. **Second sweep over the remaining pins** (7, 12, 13, 16, 22, 23, 26, 27): driving **GP16 low turned the top red off**; driving it high turned it on. GP16 is the 4th red. 5. **Re-mapped all eight at low PWM duty**, one pin in PWM function at a time with the rest driven low, to eliminate camera bloom — this is the strip that produced the table above (`grid_e.jpg`). 6. **Cross-checked with pair patterns**: `{GP4, GP5, GP17, GP18}` lit the bottom two of each column; `{GP0, GP6, GP16, GP24}` lit the top two (`grid_xy.jpg`). Both match the table. ### Method note: the camera will lie to you Two traps, both of which produced a wrong intermediate map: - **Bloom.** At full brightness the LEDs flare into their neighbours, and a single lit LED reads as two or three. Every ambiguous frame here was resolved by dropping to PWM duty ~1200 and `eq=brightness=-0.30` on the ffmpeg filter chain. Do the mapping dim, not bright. - **Auto-exposure.** The camera re-gains between shots, so "this LED looks brighter than in the last photo" means nothing across frames. Only within-frame comparisons are valid. (A stale-first-frame effect was suspected and ruled out: capturing 15 frames and keeping the last reproduced the same result as `-frames 1`.) ## Resolves / updates other files - `pinmapping_findings.md` §4 listed GP0 as *"dynamic: LED/switch"* (correct — it is the top white LED) and GP25 as *"likely status LED"* — **wrong**, GP25 drives no LED and remains unidentified. - `power_hold_findings.md` and `button_findings.md` both list **GP16** as an unexplained driven PIO clock output under TE firmware. It is the **top red LED**. The TE firmware presumably drives it from PIO for glitch-free brightness ramping alongside the other seven. ## Remaining unidentified GPIOs GP7, GP12, GP13, GP22, GP23, GP25, GP26, GP27 — none of them light an LED (swept both high and low with no visible change). [2026-07-19 10:17:20] tool result: Write File created successfully at: /home/agent/TE_ting/led_findings.md (file state is current in your context — no need to Read it back) [2026-07-19 10:17:29] tool use: Write file_path: /home/agent/TE_ting/scratchpad/led_test.py content: """EP-2350 LED helper / demo — run on the device (stock MicroPython). python3 scratchpad/rp.py scratchpad/led_test.py Map (see led_findings.md): one GPIO per LED, active high. """ from machine import Pin, PWM import time Pin(2, Pin.OUT, value=1) # power latch — always first RED = [16, 24, 18, 17] # top -> bottom WHITE = [0, 6, 4, 5] # top -> bottom ALL = RED + WHITE pins = [Pin(n, Pin.OUT, value=0) for n in ALL] def set_bits(mask): """Bit 0..3 = red top..bottom, bit 4..7 = white top..bottom.""" for i, p in enumerate(pins): p.value((mask >> i) & 1) def chase(rounds=3, ms=60): for _ in range(rounds): for p in pins: p.value(1) time.sleep_ms(ms) p.value(0) def dim(duty=1200, freq=1000): """PWM all eight. NB: GP0 and GP16 share a PWM channel — see led_findings.""" return [PWM(Pin(n), freq=freq, duty_u16=duty) for n in ALL] def standby_glow(): """The dim glow seen at session start: internal pull-ups, no PWM needed.""" for n in ALL: Pin(n, Pin.IN, Pin.PULL_UP) if __name__ == "__main__": chase() set_bits(0) print("ok") [2026-07-19 10:17:29] tool result: Write File created successfully at: /home/agent/TE_ting/scratchpad/led_test.py (file state is current in your context — no need to Read it back) [2026-07-19 10:17:32] tool use: Bash command: python3 scratchpad/rp.py scratchpad/led_test.py description: Run the LED helper script on device [2026-07-19 10:17:33] tool result: Bash ok [2026-07-19 10:17:43] tool use: Write file_path: /home/agent/.claude/projects/-home-agent-TE-ting/memory/ep2350-led-map.md content: --- name: ep2350-led-map description: EP-2350 LED pins — 8 direct active-high GPIOs; red 16/24/18/17, white 0/6/4/5 (top→bottom) metadata: type: project --- EP-2350 LEDs (solved 2026-07-19, see `led_findings.md`): eight LEDs, eight dedicated GPIOs, **active high**, no matrix/enable line. Top→bottom: red = **GP16, GP24, GP18, GP17**; white = **GP0, GP6, GP4, GP5**. Note the non-obvious ordering (GP6 above GP4/GP5). - Full brightness is just a digital `1` — pad drive strength (4 mA vs 12 mA) makes no visible difference; series resistors set the current. - Dimming = plain PWM. **GP0 and GP16 share a PWM slice/channel**, so top red and top white can't be PWM-dimmed independently. - A "dim glow" on all 8 is just internal pull-ups left enabled — that's what the button/knob scripts ([[ep2350-button-map]], [[ep2350-volume-knob]]) leave behind. - Resolves GP16, previously logged as an unexplained PIO clock output. GP25 is **not** an LED despite the old "likely status LED" note. - Camera mapping method: map at LOW PWM duty with a darkened ffmpeg filter — at full brightness LED bloom makes one lit LED read as three. [2026-07-19 10:17:43] tool result: Write File created successfully at: /home/agent/.claude/projects/-home-agent-TE-ting/memory/ep2350-led-map.md [2026-07-19 10:17:48] tool use: Edit replace_all: false file_path: /home/agent/.claude/projects/-home-agent-TE-ting/memory/MEMORY.md old_string: - [EP-2350 audio tone status](ep2350-audio-tone-status.md) new_string: - [EP-2350 LED map](ep2350-led-map.md) — SOLVED: 8 direct active-high GPIOs; red 16/24/18/17, white 0/6/4/5; GP16 was the "unexplained PIO clock" - [EP-2350 audio tone status](ep2350-audio-tone-status.md) [2026-07-19 10:17:48] tool result: Edit The file /home/agent/.claude/projects/-home-agent-TE-ting/memory/MEMORY.md has been updated successfully. (file state is current in your context — no need to Read it back) [2026-07-19 10:18:01] agent: Solved. The LEDs are the simplest possible scheme — **eight dedicated GPIOs, one per LED, active high**. No matrix, no charlieplexing, no enable line. | Position (top → bottom) | Red | White | |---|---:|---:| | 1 (nearest handle) | **GP16** | **GP0** | | 2 | **GP24** | **GP6** | | 3 | **GP18** | **GP4** | | 4 | **GP17** | **GP5** | Note the columns aren't in GPIO order — GP6 sits above GP4/GP5. **Control:** - `1` = full brightness, `0` = off. Pad drive strength is irrelevant (4 mA vs 12 mA gave no visible change — the series resistors set the current), so a plain digital high already *is* max brightness. - Dimming is plain PWM; duty ≈ 1200/65535 @ 1 kHz is a nice indicator level. - **Gotcha: GP0 and GP16 share a PWM slice/channel**, so top red and top white can't be PWM-dimmed independently. This bit me mid-investigation — a sweep that muxed all eight pins to PWM made the top white silently mirror GP16. **Why they were all dimly lit:** not a hardware feature — leftover state from the button/knob sessions, which set every GPIO to `Pin.IN, Pin.PULL_UP`. The ~50–80 kΩ internal pull-up sources ~40 µA into each LED. I reproduced it exactly. It's a free "standby glow" mode if you want one. **Two corrections to earlier findings:** - **GP16** — logged in `power_hold_findings.md` and `pinmapping_findings.md` as an unexplained high-rate PIO clock output — is the **top red LED**. - **GP25** was guessed as "likely status LED"; it drives no LED and is still unidentified. Getting there took two wrong intermediate maps: the initial 8-pin candidate set from the TE firmware snapshot included GP25 (dead) and missed GP16, and camera bloom at full brightness made single LEDs read as three. Remapping at low PWM duty with a darkened capture fixed it, cross-checked with pair patterns. Written up in `led_findings.md`, with a reusable helper at `scratchpad/led_test.py` (verified running on the device). Device is left latched with all LEDs off.