@felmue The internal I2C bus scan works for me, I get the same result as you for that one. But the grove Port A fails with the low voltage on pin 32. I can even use jumper pins to run I2C devices from the top header by using jumper cables. I tested it with 2 brand new StickC Plus2 so the chances that both of them were damaged in the same way by me is unlikely. I am also somewhat experienced with ESP32 and other microcontrollers. I am out of ideas, I guess I can try to contact M5 support.

@felmue I looked at the example . Thanks for that. I created something similar in Arduino for my testing earlier.

@teastain I am using Arduino and Arduino IDE as well. However, I wasnt able to use the grove Port A for I2C in UI Flow 2 either.

I started with this code to do an I2C wire scan. It returns Error 5 at all addresses, No I2C devices found when I have I2C devices connected.

#include <Arduino.h>
#include <Wire.h>

  // Board Pin Definitions
#define PIN_POWER_HOLD 4
#define PIN_LCD_BL 27
  //Internal I2C BUS 6-Axis posture sensor (MPU6886) & RTC (BM8563)
#define PIN_INTERNAL_SDA 21
#define PIN_INTERNAL_SCL 22
  //Grove Connector I2C BUS (Port A)
#define PIN_GROVE_SDA 32
#define PIN_GROVE_SCL 33

void wireScanTest() {
  Wire.begin(PIN_GROVE_SDA, PIN_GROVE_SCL, 400000);
  //Wire.begin(PIN_INTERNAL_SDA, PIN_INTERNAL_SCL, 400000);

  byte error, address;
  int nDevices = 0;

  delay(5000);

  Serial.println("Scanning for I2C devices ...");
  for (address = 0x01; address < 0x7f; address++) {
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
    if (error == 0) {
      Serial.printf("I2C device found at address 0x%02X\n", address);
      nDevices++;
    } else if (error != 2) {
      Serial.printf("Error %d at address 0x%02X\n", error, address);
    }
  }
  if (nDevices == 0) {
    Serial.println("No I2C devices found");
  }
}

void setup() {
  pinMode(PIN_POWER_HOLD, OUTPUT);
  digitalWrite(PIN_POWER_HOLD, HIGH);
  pinMode(PIN_LCD_BL, OUTPUT);
  digitalWrite(PIN_LCD_BL, HIGH);
  Serial.begin(115200);

  wireScanTest();
}

void loop() {}

So I made this to test the pins and i get the strange voltage on pin 32.

#include <Arduino.h>
#include <Wire.h>

  // Board Pin Definitions
#define PIN_POWER_HOLD 4
#define PIN_LCD_BL 27
  //Grove Connector I2C BUS (Port A)
#define PIN_GROVE_SDA 32
#define PIN_GROVE_SCL 33

void setup() {
  pinMode(PIN_POWER_HOLD, OUTPUT);
  digitalWrite(PIN_POWER_HOLD, HIGH);
  pinMode(PIN_LCD_BL, OUTPUT);
  digitalWrite(PIN_LCD_BL, HIGH);
  pinMode(PIN_GROVE_SDA, OUTPUT);
  digitalWrite(PIN_GROVE_SDA, HIGH);
  pinMode(PIN_GROVE_SCL, OUTPUT);
  digitalWrite(PIN_GROVE_SCL, HIGH);

  Serial.begin(115200);
}

void loop() {
  delay(5000);
  digitalWrite(PIN_GROVE_SDA, LOW);
  digitalWrite(PIN_GROVE_SCL, LOW);
  delay(5000);
  digitalWrite(PIN_GROVE_SDA, HIGH);
  digitalWrite(PIN_GROVE_SCL, HIGH);
}

I am trying to use the grove port on my M5 StickC Plus2 boards but they are not working. Ground is fine, I have 5V on the 5V pin, G33 shows 3.3V when I set it to output high, but G32 only shows 0.89V when set to high. I have tested 2 M5 sticks and they both have this problem. Has anyone else encountered this or know how to fix this problem?