feat(amoled-18): auto-detect CO5300/CST816 panel revision

Waveshare ships two hardware revisions under "ESP32-S3-Touch-AMOLED-1.8":
the original (SH8601 display + FT3168 touch @0x38) and a later one
(CO5300 display + CST816 touch @0x15). On the later board the SH8601
driver left the panel blank and the FT3168 probe spammed
ESP_ERR_INVALID_STATE because nothing answers at 0x38.

Detect the revision at boot by probing the touch address and pick the
matching drivers, so one binary drives both boards:

- board_rev.{h}/board_init.cpp: probe 0x15 (CST816) vs 0x38 (FT3168)
- display.cpp: instantiate Arduino_CO5300 or Arduino_SH8601 behind a
  shared Arduino_OLED*; CO5300 gets a 16px column offset to center the
  368-wide image (verified on hardware)
- touch.cpp: one FocalTech-style reader (regs 0x02..0x06) for both
  chips, address chosen by revision
- board.h: add CST816_ADDR 0x15
- CLAUDE.md: document the dual revision

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -9,7 +9,7 @@ never see board-specific code. See [`docs/porting/adding-a-board.md`](docs/porti
 Two reference ports today:
 
 - `boards/waveshare_amoled_216/` — original Waveshare ESP32-S3-Touch-AMOLED-2.16 (CO5300, 480×480 square, CST9220 touch, IMU rotation). Build env: `waveshare_amoled_216`.
-- `boards/waveshare_amoled_18/` — Waveshare ESP32-S3-Touch-AMOLED-1.8 (SH8601, 368×448 portrait, FT3168 touch, XCA9554 IO expander). Build env: `waveshare_amoled_18`.
+- `boards/waveshare_amoled_18/` — Waveshare ESP32-S3-Touch-AMOLED-1.8 (368×448 portrait, XCA9554 IO expander). Build env: `waveshare_amoled_18`. **Two panel revisions are auto-detected at boot** (`board_rev()` in `board_init.cpp`, enum in `board_rev.h`): original = SH8601 display + FT3168 touch (0x38); later = CO5300 display + CST816 touch (0x15). One binary drives both.
 
 The shared code calls a small HAL (`firmware/src/hal/`) that each board implements: display, touch, input, power, IMU. Optional features are guarded by `BoardCaps` (runtime) and `BOARD_HAS_*` (compile-time) rather than `#ifdef BOARD_*`.
 
@@ -25,8 +25,9 @@ Connects to a host daemon over BLE; daemon polls Anthropic API for usage data. T
 - Buttons: GPIO 0 (left → Space/voice-mode), GPIO 18 (right → Shift+Tab/mode-toggle), AXP PKEY (middle → cycle screens; on splash → cycle animations)
 
 ### AMOLED-1.8 (newer port)
-- Display: **SH8601** AMOLED via QSPI (CS=12, **SCLK=11** ← different!, SDIO0..3=4..7, RST routed via XCA9554 EXIO1)
-- Touch: **FT3168** via I2C (SDA=15, SCL=14, INT=21, addr=0x38). Driven by minimal inline reader in `main.cpp` (FocalTech standard register layout — avoids vendoring the GPLv3 `Arduino_DriveBus` library).
+**Two hardware revisions ship under this name; the firmware probes I2C at boot and picks drivers automatically (`board_rev()`):**
+- Display: **SH8601** (original) or **CO5300** (later rev) AMOLED via QSPI (CS=12, **SCLK=11** ← different!, SDIO0..3=4..7, RST routed via XCA9554 EXIO1). Both are `Arduino_OLED` subclasses held behind one base pointer in `display.cpp`. The CO5300's 368-wide active area starts at GRAM column 16, so it gets `CO5300_COL_OFFSET 16` to center; SH8601 needs none.
+- Touch: **FT3168** @ 0x38 (original) or **CST816** @ 0x15 (later rev), via I2C (SDA=15, SCL=14, INT=21). Both expose the same FocalTech-style data layout at regs 0x02..0x06, so one inline reader in `touch.cpp` serves both — only the address differs. Avoids vendoring the GPLv3 `Arduino_DriveBus` library. Revision is detected by which touch address ACKs (CST816 present ⇒ CO5300 panel).
 - PMU: AXP2101 @ 0x34 (same chip as 2.16 — `XPowersLib` reused; battery is an optional kit add-on but PMU + charging circuitry are populated)
 - IMU: QMI8658 @ 0x6B (same chip — initialized for I2C bus health, rotation logic disabled)
 - IO expander: **XCA9554 / PCA9554** @ I2C 0x20. Gates LCD_RST, TP_RST, audio amp enable, and reads the PWR button. **`io_expander_init()` MUST run before `gfx->begin()` or `ft3168_init()`** — otherwise display/touch stay in reset and silently fail. PWR button is on EXIO4, active HIGH (verified empirically with the deleted `iox` serial debug command).

firmware/src/boards/waveshare_amoled_18/board.h

@@ -26,9 +26,12 @@
 #define IIC_SDA              15
 #define IIC_SCL              14
 
-// ---- Touch (FT3168 via vendored minimal I2C reader) ----
+// ---- Touch (minimal inline I2C reader; chip varies by board revision) ----
+// Both controllers share the FocalTech-style data layout at regs 0x02..0x06,
+// so only the I2C address differs. Revision is detected in board_init().
 #define TP_INT               21
-#define FT3168_ADDR          0x38
+#define FT3168_ADDR          0x38   // original revision
+#define CST816_ADDR          0x15   // later (CO5300) revision
 
 // ---- PMU ----
 #define AXP2101_ADDR         0x34

firmware/src/boards/waveshare_amoled_18/board_init.cpp

@@ -1,11 +1,33 @@
 #include "board.h"
+#include "board_rev.h"
 #include "io_expander.h"
 #include <Arduino.h>
 #include <Wire.h>
 
 // AMOLED-1.8 also needs the XCA9554 IO expander up first — the display
 // and touch controllers stay in reset until EXIO0..1 go HIGH.
+
+static BoardRev g_rev = REV_SH8601_FT3168;
+
+BoardRev board_rev(void) { return g_rev; }
+
+static bool i2c_present(uint8_t addr) {
+    Wire.beginTransmission(addr);
+    return Wire.endTransmission() == 0;
+}
+
 extern "C" void board_init(void) {
     Wire.begin(IIC_SDA, IIC_SCL);
     io_expander_init();
+    delay(10);  // let the touch controller exit reset before probing
+
+    // Detect the panel revision by which touch controller answers. CST816
+    // (0x15) ships on the CO5300 panel; FT3168 (0x38) on the original SH8601.
+    if (i2c_present(CST816_ADDR)) {
+        g_rev = REV_CO5300_CST816;
+        Serial.println("Board revision: CO5300 + CST816");
+    } else {
+        g_rev = REV_SH8601_FT3168;
+        Serial.println("Board revision: SH8601 + FT3168");
+    }
 }

firmware/src/boards/waveshare_amoled_18/board_rev.h

@@ -0,0 +1,18 @@
+#pragma once
+
+// Two shipping hardware revisions of the Waveshare 1.8" AMOLED differ only in
+// their bonded panel module:
+//   - original: SH8601 display (QSPI) + FT3168 touch (I2C 0x38)
+//   - later:    CO5300 display (QSPI) + CST816 touch (I2C 0x15)
+// Everything else (PMU, IMU, IO expander, pinout) is identical. We detect the
+// revision at boot by probing the touch controller's I2C address — board_init()
+// sets it BEFORE display_hal_init()/touch_hal_init() so both pick the right
+// driver. The touch chip's presence is a reliable proxy for the panel module.
+
+enum BoardRev {
+    REV_SH8601_FT3168 = 0,   // original
+    REV_CO5300_CST816 = 1,   // later revision
+};
+
+// Valid only after board_init() has run.
+BoardRev board_rev(void);

firmware/src/boards/waveshare_amoled_18/display.cpp

@@ -1,5 +1,6 @@
 #include "../../hal/display_hal.h"
 #include "board.h"
+#include "board_rev.h"
 #include "io_expander.h"
 #include <Arduino.h>
 #include <Arduino_GFX_Library.h>
@@ -8,17 +9,31 @@
 // Display reset is routed through the XCA9554 IO expander (EXIO1) which
 // must be initialized + released before gfx->begin() runs — main.cpp
 // arranges this by calling display_hal_init() after io_expander_init().
+//
+// Two panel revisions: original SH8601 and a later CO5300 module. Both are
+// Arduino_OLED subclasses, so we hold the chosen one behind a base pointer.
+// The CO5300's 368-wide active area starts partway into the controller GRAM,
+// so it needs a column offset to center the image (the SH8601 needs none).
+
+#define CO5300_COL_OFFSET  16   // centers the 368-wide image (verified on panel)
 
 static Arduino_DataBus* bus = nullptr;
-static Arduino_SH8601*  gfx = nullptr;
+static Arduino_OLED*    gfx = nullptr;
 
 void display_hal_init(void) {
     bus = new Arduino_ESP32QSPI(
         LCD_CS, LCD_SCLK, LCD_SDIO0, LCD_SDIO1, LCD_SDIO2, LCD_SDIO3);
-    // SH8601 constructor: (bus, rst, rotation, w, h)
+    if (board_rev() == REV_CO5300_CST816) {
+        // CO5300: (bus, rst, rotation, w, h, col_off1, row_off1, col_off2, row_off2)
+        gfx = new Arduino_CO5300(
+            bus, GFX_NOT_DEFINED /* reset via XCA9554 */, 0,
+            LCD_WIDTH, LCD_HEIGHT, CO5300_COL_OFFSET, 0, 0, 0);
+    } else {
+        // SH8601: (bus, rst, rotation, w, h)
         gfx = new Arduino_SH8601(
             bus, GFX_NOT_DEFINED /* reset via XCA9554 */, 0,
             LCD_WIDTH, LCD_HEIGHT);
+    }
 }
 
 void display_hal_begin(void) {

firmware/src/boards/waveshare_amoled_18/touch.cpp

@@ -1,10 +1,12 @@
 #include "../../hal/touch_hal.h"
 #include "board.h"
+#include "board_rev.h"
 #include <Arduino.h>
 #include <Wire.h>
 
-// Minimal FT3168 reader (FocalTech standard register layout). Avoids
-// vendoring Waveshare's GPLv3 Arduino_DriveBus library.
+// Minimal capacitive-touch reader. Both shipping panel revisions expose the
+// FocalTech-style touch-data layout, so one read path serves both — only the
+// I2C address differs (FT3168 @ 0x38 vs CST816 @ 0x15), chosen from board_rev().
 //   reg 0x02:        low nibble = active finger count
 //   reg 0x03 / 0x04: X1 high (low nibble) + X1 low
 //   reg 0x05 / 0x06: Y1 high (low nibble) + Y1 low
@@ -13,16 +15,17 @@ static volatile bool     touch_data_ready = false;
 static volatile bool     touch_pressed = false;
 static volatile uint16_t touch_x = 0;
 static volatile uint16_t touch_y = 0;
+static uint8_t           touch_addr = FT3168_ADDR;
 
 static void IRAM_ATTR touch_isr(void) {
     touch_data_ready = true;
 }
 
-static void ft3168_read_into_shared_state(void) {
-    Wire.beginTransmission(FT3168_ADDR);
+static void touch_read_into_shared_state(void) {
+    Wire.beginTransmission(touch_addr);
     Wire.write(0x02);
     if (Wire.endTransmission(false) != 0) { touch_pressed = false; return; }
-    if (Wire.requestFrom(FT3168_ADDR, (uint8_t)5) != 5) { touch_pressed = false; return; }
+    if (Wire.requestFrom(touch_addr, (uint8_t)5) != 5) { touch_pressed = false; return; }
     uint8_t fingers = Wire.read() & 0x0F;
     uint8_t xH = Wire.read();
     uint8_t xL = Wire.read();
@@ -38,31 +41,38 @@ static void ft3168_read_into_shared_state(void) {
 }
 
 void touch_hal_init(void) {
-    // Power-mode register 0xA5 = 0x00: active scanning.
-    Wire.beginTransmission(FT3168_ADDR);
+    bool is_cst816 = (board_rev() == REV_CO5300_CST816);
+    touch_addr = is_cst816 ? CST816_ADDR : FT3168_ADDR;
+
+    if (!is_cst816) {
+        // FT3168 power-mode register 0xA5 = 0x00: active scanning.
+        // (CST816 reports by default; no equivalent setup needed.)
+        Wire.beginTransmission(touch_addr);
         Wire.write(0xA5);
         Wire.write(0x00);
         Wire.endTransmission();
+    }
 
-    // Verify device ID register 0xA0 (FT3168 reports 0x03 but Waveshare's
-    // panel sometimes returns 0x86 — log but don't fail).
-    Wire.beginTransmission(FT3168_ADDR);
-    Wire.write(0xA0);
-    if (Wire.endTransmission(false) == 0 && Wire.requestFrom(FT3168_ADDR, (uint8_t)1) == 1) {
-        Serial.printf("FT3168 ID=0x%02X\n", Wire.read());
+    // Verify the controller answers. FT3168 chip-id is reg 0xA0; CST816 reg 0xA7.
+    uint8_t id_reg = is_cst816 ? 0xA7 : 0xA0;
+    Wire.beginTransmission(touch_addr);
+    Wire.write(id_reg);
+    if (Wire.endTransmission(false) == 0 && Wire.requestFrom(touch_addr, (uint8_t)1) == 1) {
+        Serial.printf("Touch %s ID=0x%02X (addr 0x%02X)\n",
+                      is_cst816 ? "CST816" : "FT3168", Wire.read(), touch_addr);
     } else {
-        Serial.println("FT3168 ID read failed");
+        Serial.printf("Touch ID read failed (addr 0x%02X)\n", touch_addr);
     }
 
     pinMode(TP_INT, INPUT_PULLUP);
     attachInterrupt(TP_INT, touch_isr, FALLING);
-    Serial.println("FT3168 attached on INT pin");
+    Serial.println("Touch attached on INT pin");
 }
 
 void touch_hal_read(uint16_t* x, uint16_t* y, bool* pressed) {
     if (touch_data_ready) {
         touch_data_ready = false;
-        ft3168_read_into_shared_state();
+        touch_read_into_shared_state();
     }
     *x = touch_x;
     *y = touch_y;