Fix M5Stack Unit C6L: correct pin config and add IO expander support

src/helpers/esp32/SerialBLEInterface.cpp

@@ -1,4 +1,5 @@
 #include "SerialBLEInterface.h"
+#include <esp_mac.h>
 
 // See the following for generating UUIDs:
 // https://www.uuidgenerator.net/

variants/m5stack_unit_c6l/UnitC6LBoard.h

@@ -1,15 +1,130 @@
 #pragma once
 
 #include <Arduino.h>
+#include <Wire.h>
 #include <helpers/ESP32Board.h>
 
+// PI4IO I/O Expander (I2C address 0x43)
+// Pin mapping:
+//   P0 = Button (active low)
+//   P1 = (unused input)
+//   P5 = LNA_EN (LNA Enable)
+//   P6 = ANT_SW (RF Switch)
+//   P7 = NRST (LoRa Reset)
+#define PI4IO_ADDR 0x43
+
+// PI4IO registers
+#define PI4IO_REG_CHIP_RESET 0x01
+#define PI4IO_REG_IO_DIR 0x03
+#define PI4IO_REG_OUT_SET 0x05
+#define PI4IO_REG_OUT_H_IM 0x07
+#define PI4IO_REG_IN_DEF_STA 0x09
+#define PI4IO_REG_PULL_EN 0x0B
+#define PI4IO_REG_PULL_SEL 0x0D
+#define PI4IO_REG_IN_STA 0x0F
+#define PI4IO_REG_INT_MASK 0x11
+#define PI4IO_REG_IRQ_STA 0x13
+
 class UnitC6LBoard : public ESP32Board {
+private:
+  bool i2c_write_byte(uint8_t addr, uint8_t reg, uint8_t value) {
+    Wire.beginTransmission(addr);
+    Wire.write(reg);
+    Wire.write(value);
+    return Wire.endTransmission() == 0;
+  }
+
+  bool i2c_read_byte(uint8_t addr, uint8_t reg, uint8_t *value) {
+    Wire.beginTransmission(addr);
+    Wire.write(reg);
+    if (Wire.endTransmission() != 0) return false;
+    if (Wire.requestFrom(addr, (uint8_t)1) != 1) return false;
+    if (!Wire.available()) return false;
+    *value = Wire.read();
+    return true;
+  }
+
+  void initIOExpander() {
+    uint8_t in_data;
+
+    // Reset the I/O expander
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_CHIP_RESET, 0xFF);
+    delay(10);
+
+    i2c_read_byte(PI4IO_ADDR, PI4IO_REG_CHIP_RESET, &in_data);
+    delay(10);
+
+    // Set P5, P6, P7 as outputs (0: input, 1: output)
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_IO_DIR, 0b11100000);
+    delay(10);
+
+    // Disable High-Impedance for used pins
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_OUT_H_IM, 0b00011100);
+    delay(10);
+
+    // Pull up/down select (0: down, 1: up)
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_PULL_SEL, 0b11100011);
+    delay(10);
+
+    // Pull up/down enable (0: disable, 1: enable)
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_PULL_EN, 0b11100011);
+    delay(10);
+
+    // Default input state for P0, P1 (buttons)
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_IN_DEF_STA, 0b00000011);
+    delay(10);
+
+    // Enable interrupts for P0, P1 (0: enable, 1: disable)
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_INT_MASK, 0b11111100);
+    delay(10);
+
+    // Set P7 (Reset) high, P5 and P6 will be set after
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_OUT_SET, 0b10000000);
+    delay(10);
+
+    // Clear IRQ status
+    i2c_read_byte(PI4IO_ADDR, PI4IO_REG_IRQ_STA, &in_data);
+
+    // Enable RF switch (P6 high) and LNA (P5 high)
+    i2c_read_byte(PI4IO_ADDR, PI4IO_REG_OUT_SET, &in_data);
+    in_data |= (1 << 6);  // P6 = RF Switch = HIGH
+    in_data |= (1 << 5);  // P5 = LNA Enable = HIGH
+    i2c_write_byte(PI4IO_ADDR, PI4IO_REG_OUT_SET, in_data);
+  }
+
 public:
   void begin() {
     ESP32Board::begin();
+
+    // Initialize I/O expander for LoRa RF control
+    initIOExpander();
+
+#ifdef PIN_BUZZER
+    pinMode(PIN_BUZZER, OUTPUT);
+    digitalWrite(PIN_BUZZER, LOW);
+#endif
   }
 
   const char* getManufacturerName() const override {
-    return "Unit C6L";
+    return "M5Stack Unit C6L";
+  }
+
+  // Read button state from I/O expander P0 (active low)
+  bool isButtonPressed() {
+    uint8_t in_data = 0xFF;
+    if (!i2c_read_byte(PI4IO_ADDR, PI4IO_REG_IN_STA, &in_data)) {
+      return false;
+    }
+    return !(in_data & 0x01);
+  }
+
+#ifdef PIN_BUZZER
+  void playTone(uint16_t frequency, uint16_t duration_ms) {
+    tone(PIN_BUZZER, frequency, duration_ms);
+  }
+
+  void stopTone() {
+    noTone(PIN_BUZZER);
   }
+#endif
 };

variants/m5stack_unit_c6l/platformio.ini

@@ -5,27 +5,35 @@ board_build.partitions = min_spiffs.csv ; get around 4mb flash limit
 build_flags =
   ${esp32c6_base.build_flags}
   ${sensor_base.build_flags}
-  -I variants/M5Stack_Unit_C6L
-  -D P_LORA_TX_LED=15
+  -I variants/m5stack_unit_c6l
+  -D ARDUINO_USB_CDC_ON_BOOT=1
+  -D ARDUINO_USB_MODE=1
+  ; LoRa SX1262 SPI pins
   -D P_LORA_SCLK=20
   -D P_LORA_MISO=22
   -D P_LORA_MOSI=21
   -D P_LORA_NSS=23
   -D P_LORA_DIO_1=7
   -D P_LORA_BUSY=19
   -D P_LORA_RESET=-1
-  -D PIN_BUZZER=11
-  -D PIN_BOARD_SDA=16
-  -D PIN_BOARD_SCL=17
-  -D SX126X_RXEN=5
+  ; I2C pins (PI4IO expander + sensors)
+  -D PIN_BOARD_SDA=10
+  -D PIN_BOARD_SCL=8
+  ; SX1262 configuration
   -D SX126X_DIO2_AS_RF_SWITCH=true
-  -D SX126X_DIO3_TCXO_VOLTAGE=1.8
+  -D SX126X_DIO3_TCXO_VOLTAGE=3.0
   -D SX126X_CURRENT_LIMIT=140
   -D SX126X_RX_BOOSTED_GAIN=1
+  ; Radio configuration
   -D RADIO_CLASS=CustomSX1262
   -D WRAPPER_CLASS=CustomSX1262Wrapper
   -D LORA_TX_POWER=22
   -D DISABLE_WIFI_OTA=1
+  ; NeoPixel LED for TX indication
+  -D P_LORA_TX_NEOPIXEL_LED=2
+  ; Buzzer
+  -D PIN_BUZZER=11
+  ; GPS on Grove port
   -D GPS_RX=4
   -D GPS_TX=5
 build_src_filter = ${esp32c6_base.build_src_filter}