Clock / Timing problem in I2C

[maya16]

I am trying to run a loopback test with 2 i2c's on the same board. The onboard leds need to light up on successful transmission and reception, the problem is the leds light up when in debug mode, going line by line, but not in stand

#define I2C1_ADD (0x15<<1)
#define I2C2_ADD (0x42<<1)

uint8_t I2C1_tx='1';
uint8_t I2C2_tx='2';
uint8_t I2C1_rx,I2C2_rx;

HAL_I2C_Slave_Receive_IT(&hi2c2,&I2C2_rx,sizeof(I2C1_tx));
HAL_Delay(100);
HAL_I2C_Master_Transmit(&hi2c1,I2C2_ADD,&I2C1_tx,sizeof(I2C1_tx),1000);


HAL_I2C_Slave_Receive_IT(&hi2c1,&I2C1_rx,sizeof(I2C2_tx));
HAL_Delay(100);
HAL_I2C_Master_Transmit(&hi2c2,I2C1_ADD,&I2C2_tx,sizeof(I2C2_tx),1000);


while(1)
{
 if(I2C2_rx==I2C1_tx)
 {
	 HAL_GPIO_WritePin(GPIOG,GPIO_PIN_13,SET);
 HAL_Delay(100);
	
 }
 if(I2C1_rx==I2C2_tx)
  {
 	 HAL_GPIO_WritePin(GPIOG,GPIO_PIN_14,SET);
 	 HAL_Delay(500);
  }
}

alone. Can someone plz suggest what might be wrong.

[TDK]

Don't switch between slave and master. Leave I2C1 as master and I2C2 as slave.

Try declaring I2C1_rx I2C2_rx as volatile, since they are being modified by the DMA.

volatile uint8_t I2C1_rx;
volatile uint8_t I2C2_rx;

[Saket_Om]

Hello @maya16 

Please ensure that the interrupt priorities are configured correctly. The interrupt priority for receive should be higher (i.e., numerically lower) than the interrupt priority for transmit.

[Andrew Neil]

You already have a thread on this - marked as solved:

I2C Loopback Test using STM32F429ZI