You need to use Wire1 to access the external devices.
I vaguely remember reading about this issue before but as I don't have arduino I had forgotten about it.
Thanks for the reminder.

With the following ini file (PlattformIO config file)

[env:miniscale]
platform = espressif32@6.1.0
board = m5stick-c
framework = arduino
lib_ldf_mode = deep
monitor_speed = 115200
build_flags = 
	-DCORE_DEBUG_LEVEL=0
	-Wl,--allow-multiple-definition
lib_deps = 
	https://github.com/m5stack/M5StickCPlus2.git
	m5stack/M5Unit-ENV@^1.0.1

Not knowing why, but I need the "-Wl" to run at all and the "--allow-multiple-definition" flag for the hat to work in conjunction with sensors mounted to the groove port.
It worked, however, I need to change the I2C begin call from "Wire0" (just called Wire) to the secondary I2C channel Wire1

Before:

while (!qmp.begin(&Wire, QMP6988_SLAVE_ADDRESS_L, 0, 26, 400000U)) {
     Serial.println("QMP6988 not found");
 }

After:

while (!qmp.begin(&Wire1, QMP6988_SLAVE_ADDRESS_L, 0, 26, 400000U)) {
     Serial.println("QMP6988 not found");
 }

Maybe this helps someone in the future :)

at least we know now that the hardware is ok.

Apart from that I am stumped. Sorry.

Thanks
Felix

Do you know were the difference between UIFlow 2 and Arduino is?

hmm, that is really strange. Do you have any other hat to try if the hat port works for you in general?

ENV III hat is supported in UIFlow2. Maybe try with UIFlow2? Just to see if it works that way.

Thanks
Felix

Could it be that the hat port uses another Wire?

Propably it is a hardware failure, I do not get any i2c signals back.

Wil return it and run it with new hardware. I update the thread when I heard back from the seller.

Thanks for your help!

Greetings Pascal

hmm, have you tried to power cycle M5StickCPlus2?

1. disconnect USB
2. remove HAT
3. press and hold power button until green LED lights up
4. release power button - green LED goes dark - M5StickCPlus2 is now off
5. re-attach HAT
6. re-connect USB - M5StickCPlus2 powers on
7. re-test

Thanks
Felix

P.S. if that doesn't make the HAT show up in the I2C scan or make it work with the original program then I am afraid that yes, there might be a hardware issue.

The port scan went as expect, only internals are found.

I2C Scan - internal
................................................................................0x51 ......................0x68 ......................
I2C Scan - Groove Port
..............................................................................................................................
I2C Scan - Hat Port
..............................................................................................................................

Does that mean a hardware error?

Greetings Pascal

Strangely, they are now not showing up (not found is now in the log). That wasnt before.

from your first log I think the ENV III Hat was recognized properly else the log would have ended with either of the "Couldn't find ...".

Anyways, please find an I2C scanner for internal, Groove and Hat here.

Thanks
Felix

As a last ressort, I tried to find a I2C scanner sketch and ended up with the following code.

/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com  
*********/

#include <Wire.h>
 
void setup() {
  Wire.begin();
  Serial.begin(115200);
  Serial.println("\nI2C Scanner");
}
 
void loop() {
  byte error, address;
  int nDevices;
  Serial.println("Scanning...");
  nDevices = 0;
  for(address = 1; address < 127; address++ ) {
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
    if (error == 0) {
      Serial.print("I2C device found at address 0x");
      if (address<16) {
        Serial.print("0");
      }
      Serial.println(address,HEX);
      nDevices++;
    }
    else if (error==4) {
      Serial.print("Unknow error at address 0x");
      if (address<16) {
        Serial.print("0");
      }
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0) {
    Serial.println("No I2C devices found\n");
  }
  else {
    Serial.println("done\n");
  }
  delay(5000);          
}

I was not sure, but in all the sketches they used sda=0 and scl=26.

If I scan those, I cant get any devices found. However, if I scan the standard sda/scl = 21/22, then I find two devices (propably build into the Stick itself).

Is this a sign for an hardware failure?

Greetings Pascal

the only difference between Hat and Unit (apart from the different GPIOs it uses as @ajb2k3 pointed out) is that the Hat is powered by 3.3 V from M5StickCPlus2 whereas the Unit is powerd by 5 V (with an internal DC/DC converter).

I used the M5Unit-ENV library, copied the code you posted and manually wired the Unit to the Hat port. In other word I used exactly the code you posted without any modifications.

Sorry, at this point I have not more ideas as to why it wouldn't work on your side.

Thanks
Felix

Unfortunately I cant get either of them to connect.

Is their a difference between Hat and Unit? Which library versions did you use?

hmm, your code works for me.

Note: I don't have an ENV III hat, but I have the ENV III unit which I used to simulate ENV III hat. So it could be something subtle between the two making it work for me.

That said, I suggest you first try with the ENV III example alone and if that still doesn't work try to only init and read either qmp or sht3x and see how that goes.

Thanks
Felix