Issue with start condition I2C

Projects Networking, Protocols, and Devices
1

Dear Arduino enthusiasts,

I need your help to understand how to configure the start condition of I2C transmission. I try to communicate between my arduino board and my own board (addr : 0x56).
I don't know how to explain but the clock (SCL) begins too late. I want to send 0x56(0b01010110) but I receive 0xAC (0b10101100) => because SCL begins after the first "0"...
I attached the I2C sequence that I receive and please find below my code :

#include <Wire.h>

void setup() {
    
  Wire.begin();
 // Initialization Sequence 
  Wire.beginTransmission(0x56);
  Wire.write(byte(0x06));
  Wire.write(byte(0x07));
  Wire.endTransmission();
}
void loop() {
}

Thanks in advance !

Issue_Arduino.PNG
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2

I don't know how to explain but the clock (SCL) begins too late. I want to send 0x56(0b01010110) but I receive 0xAC (0b10101100) => because SCL begins after the first "0"...

That's correct because in the Arduino (and in most datasheets too) the I2C address is specified as a 7-bit value. In the first byte transfered on the I2C signal lines the address is in the first 7 bits while the 8th bit is the flag if that transfer is a read or write. If the address of the recipient board is 0x56 it should react on that 0xAC byte because it's the board's address and the write flag.