Argon as I2C slave no ACK response

Hi there
I try to establish I2C coms among an STM32F303 configured as master and an Argon as a slave.
Both codes for master and slave are simple and compilled-flashed successfully, without errors. The STM32 transmits START-Address 0x04 and if receives ACK from Argon transmits Data = 0x00, then Data increments by 1 and so on.
The Argon doesn’t return the ACK, never.
My hardware is correct and I have checked both the SDA and SCL lines with the scope and are working just fine. I also confirmed that the state of SDA after START-Address is always high and that means there is no ACK.
I can also confirm that from the master side, the Baud Rate is 100KHz, the SMBUS and Slew Rate control is disabled, and I have tried either the Stop Delay of 10ms enabled or disabled with the same result.
Here the code of master STM32 (obtained with Flow Code):

int main()

{

	SystemClocksSetup();

	HAL_Init();

	// Enable ports ABCDEF

	__HAL_RCC_GPIOA_CLK_ENABLE();

	__HAL_RCC_GPIOB_CLK_ENABLE();

	__HAL_RCC_GPIOC_CLK_ENABLE();

	__HAL_RCC_GPIOD_CLK_ENABLE();

	__HAL_RCC_GPIOE_CLK_ENABLE();

	__HAL_RCC_GPIOF_CLK_ENABLE();


	// Value = Data to transmit
	// Calculation:
	//  Value = 0x00
	FCV_VALUE = 0x00;

	// Initialize Master
	// Call Component Macro: I2C_Master1::Initialise()
	FCD_005f1_I2C_Master1__Initialise();

	// Loop
	// Loop: While 1
	while (1)
	{

		// Delay
		// Delay: 1000 ms
		FCI_DELAYINT_MS(1000);

		// Master sends Start
		// Call Component Macro: I2C_Master1::Start()
		FCD_005f1_I2C_Master1__Start();

		// Master transmit address of Slave (0x04  for the instance)
		// Call Component Macro: ACK=I2C_Master1::TransmitByte(0x04)
		FCV_ACK = FCD_005f1_I2C_Master1__TransmitByte(0x04);

		//Comment:
		//If Slave receives its
		//address, responds by
		//transmitting ACK = 0.

		// Decision
		// Decision: ACK = 0?
		if (FCV_ACK == 0)
		{

			// Output
			// Output: 1 -> B0
			FCP_SET(M, B, 0x00000001, 0, (1));
			// Master transmits Data = Value
			// Call Component Macro: ACK=I2C_Master1::TransmitByte(Value)
			FCV_ACK = FCD_005f1_I2C_Master1__TransmitByte(FCV_VALUE);

		} else {

			// Output
			// Output: 1 -> B6
			FCP_SET(M, B, 0x00000040, 6, (1));
		}

		// Master sends Stop transmition
		// Call Component Macro: I2C_Master1::Stop()
		FCD_005f1_I2C_Master1__Stop();

		// Calculation
		// Calculation:
		//  Value = Value + 1
		FCV_VALUE = FCV_VALUE + 1;

		// Delay
		// Delay: 20 ms
		FCI_DELAYBYTE_MS(20);

		// Output
		// Output: 0 -> B6
		FCP_SET(M, B, 0x00000040, 6, (0));
		// Output
		// Output: 0 -> B0
		FCP_SET(M, B, 0x00000001, 0, (0));

	}

	mainendloop: goto mainendloop;
	return 0;
}

Here is the code of slave Argon:

uint8_t data[8];
int idx;

void receiveEvent(int numOfBytes) {
    idx = 0;
    while (Wire.available()) { 
        data[idx++] = (uint8_t)Wire.read();       
  } 
}

// setup() runs once, when the device is first turned on.
void setup() {
  // Put initialization like pinMode and begin functions here.
    
    pinMode(A0,OUTPUT);
    digitalWrite(A0,LOW);
    pinMode(A1,OUTPUT);
    digitalWrite(A0,LOW);
    pinMode(A2,OUTPUT);
    digitalWrite(A2,LOW);

    Serial.begin(9600);
    Wire.begin(0x04);
    Wire.onReceive(receiveEvent);
    pinMode(D7,OUTPUT);

}

// loop() runs over and over again, as quickly as it can execute.
void loop() {

      if (idx != 0) {
        digitalWrite(D7,HIGH);
        Serial.print("RX (");
        Serial.print(idx);
        Serial.print("): ");
        for(int i=0;i<idx;i++) {
            Serial.println(data[i],HEX);  
        }
        idx = 0;
        digitalWrite(D7,LOW);
    }

}

Thanks for any help.

@photivs Did get your BQ40z50 working with the Argon?

Using a xenon with i2c I had to use external pull up resistors.

I’m using Pull Up’s also.

@Mjones Were you also working with the BQ40z50 battery management chip?

No I was working with an NFC reader. @ScruffR shared an i2c test sketch that worked well for me, im on my phone or I would post it