Hello!
I connect one I2C target and one I3C target device both to PB6/PB7, which is configured to be "mixed I3C and I2C bus" through STM32CubeIDE.
I3C parameter configuration is as below:
/* USER CODE END I3C1_Init 1 */
hi3c1.Instance = I3C1;
hi3c1.Mode = HAL_I3C_MODE_CONTROLLER;
hi3c1.Init.CtrlBusCharacteristic.SDAHoldTime = HAL_I3C_SDA_HOLD_TIME_1_5;
hi3c1.Init.CtrlBusCharacteristic.WaitTime = HAL_I3C_OWN_ACTIVITY_STATE_0;
hi3c1.Init.CtrlBusCharacteristic.SCLPPLowDuration = 0x18; // 5MHz
hi3c1.Init.CtrlBusCharacteristic.SCLI3CHighDuration = 0x18;
hi3c1.Init.CtrlBusCharacteristic.SCLODLowDuration = 0x7b; //1MHz
hi3c1.Init.CtrlBusCharacteristic.SCLI2CHighDuration = 0x7b;
hi3c1.Init.CtrlBusCharacteristic.BusFreeDuration = 0x69;
hi3c1.Init.CtrlBusCharacteristic.BusIdleDuration = 0xf6;
The problem I encountered is :
I3C devices works ok, but I2C device SCL frequency is same as I3C device, so I get wrong data when reading the I2C device , because SCL frequency is 5MHz, it is too fast for I2C device. I want the I2C device works at a lower speed, which is 1MHz in my case.
Below is the I2C waveform.
I use I3C API while comunicating with I2C device when reading one byte, as below code:
I3C_PrivateTypeDef aPrivateDescriptor[2] = {
{0x76, {aTxBuffer, 1}, {NULL, 0}, HAL_I3C_DIRECTION_WRITE},
{0x76, {NULL, 0}, {aRxBuffer, 1}, HAL_I3C_DIRECTION_READ}};
/* Prepare context buffer with the different parameters */
aContextBuffers.CtrlBuf.pBuffer = aControlBuffer;
aContextBuffers.CtrlBuf.Size = 2;
aContextBuffers.TxBuf.pBuffer = aTxBuffer;
aContextBuffers.TxBuf.Size = 1;
aContextBuffers.RxBuf.pBuffer = aRxBuffer;
aContextBuffers.RxBuf.Size = 1;
// Add descriptors to frame
HAL_I3C_AddDescToFrame(&hi3c1, NULL, aPrivateDescriptor, &aContextBuffers, aContextBuffers.CtrlBuf.Size, I3C_PRIVATE_WITHOUT_ARB_RESTART);
// Start the transfer
status = HAL_I3C_Ctrl_MultipleTransfer_IT(&hi3c1, &aContextBuffers);
if (status != HAL_OK) {
Error_Handler();
}
What might be the promblem ? Is it because I use the wrong API to communicate with I2C device ?
Is it possible to make my I2C device to work at a lower speed?
Thanks for any advice.
