Unable to communicate with LIS3DH on MagTag via I2C.

[BeldrothTheGold]

• Arduino board: Adafruit MagTag 2.9"

• Arduino IDE version (found in Arduino -> About Arduino menu): 1.8.15

• arduino-esp32 2.0.0 RC-1 installed via the boards manager

• List the steps to reproduce the problem below (if possible attach a sketch or
  copy the sketch code in too): LIST REPRO STEPS BELOW

Upload sketch, reboot and open Serial Monitor.

I believe the issue is being caused by the esp32 implementation of the TwoWire::endTransmission() function expecting the user to call Wire.write() prior to calling Wire.endTransmission()

uint8_t TwoWire::endTransmission(bool sendStop) // Assumes Wire.beginTransaction(), Wire.write()
https://github.com/espressif/arduino-esp32/blob/2af8cc34850c445b1b0694653f086b9f9b1f52f9/libraries/Wire/src/Wire.cpp#L171

Minimum Sketch to reproduce issue:

#include <Adafruit_LIS3DH.h>

Adafruit_LIS3DH lis = Adafruit_LIS3DH();

void setup() {  
  Serial.begin(115200);
  while (!Serial);
  
  if (! lis.begin(0x19)) {   // change this to 0x19 for alternative i2c address
    Serial.println("Couldnt start LIS3DH");
    while (1) yield();
  }

  Serial.print("Range = "); Serial.print(2 << lis.getRange());
  Serial.println("G");
}

void loop() {
  // put your main code here, to run repeatedly:

}

This seems like an OK workaround:

Adding the following lines to the detected() function in Adafruit_I2CDevice.cpp

bool Adafruit_I2CDevice::detected(void) {
  // Init I2C if not done yet
  if (!_begun && !begin()) {
    return false;
  }

  // A basic scanner, see if it ACK's
  _wire->beginTransmission(_addr);

#ifdef ESP32 
  // ESP32 implementation of wire expects write before endTransmission
  _wire->write(0);
#endif

  if (_wire->endTransmission() == 0) {

[caternuson]

It could be this known issue with the ESP32-S2 RC1 BSP:
espressif/arduino-esp32#5470

[BeldrothTheGold]

It could be this known issue with the ESP32-S2 RC1 BSP:
espressif/arduino-esp32#5470

Indeed the PR does fix this issue as well. OK. I will close my issue. Thanks!
espressif/arduino-esp32@e5bd18d