Modifying Open drain and push pull frequency of I3C messages with appropriate duty cycle

[Asfand]

Hi
How can we define separate frequency for open drain and push pull modes for I3C communication ?

In the documentation only the low phase is mentioned but for high phase there's no separate option for OD & PP modes.

 

Ideally I would like to do something like this 

<Context> I am working with  STM32H5RB03 as the controller and a MEMS sensor as the target. I want to do I3C communication at 12.5Mhz but the initial OD phase should have much lower frequency(<2Mhz) in order for the sensor to ACK(respond). I'm a newbie so might make basic mistakes while formulating my question, please ask if you need more clarity.

[Foued_KH]

Hello @Asfand , 

You can't define separate frequency for open drain and push pull modes for I3C communication in STM32CubeMx.
So after generate code, you should set the desired frequency 

 

/* Set bus speed to 1MHz for example*/
LL_I3C_CtrlBusConfTypeDef CtrlBusConf;
/* Calculate the new timing for Controller */
I3C_CtrlTimingComputation(&CtrlBusConf,
 HAL_RCCEx_GetPeriphCLKFreq(RCC_PERIPHCLK_I3C1),
 1000000,
 0,
 50,
 I3C_PURE_I3C_BUS);
/* Update Controller Bus characteristic */
HAL_I3C_Ctrl_BusCharacteristicConfig(&hi3c1, &CtrlBusConf);

 

after you can change it, before the transfer : 

/* Set bus speed to 5MHz for example*/
/* Calculate the new timing for Controller */
I3C_CtrlTimingComputation(&CtrlBusConf,
 HAL_RCCEx_GetPeriphCLKFreq(RCC_PERIPHCLK_I3C1),
 5000000,
 0,
 50,
 I3C_PURE_I3C_BUS);
/* Update Controller Bus characteristic */
HAL_I3C_Ctrl_BusCharacteristicConfig(&hi3c1, &CtrlBusConf);

Hope it helps!
Foued

[Asfand]

Hi @Foued_KH 
Thanks for the prompt reply.
I am using STM32CUBEIDE and it can not recognize the function 'I3C_CtrlTimingComputation' & definition 'I3C_PURE_I3C_Bus'. I have generated the example 'I3C Controller Inband interrupt' from STM32CubeMx by selecting appropriate board(not using example from Git repo).
Are these functions/definitions not included when we generate code from STM32CubeMx? If yes, can you point to the specific files I should look for ?
For ref:

Let me know If I'm missing something.

Regards,

Asfand

[Foued_KH]

Hello @Asfand , 

Sorry ! The I3C_CtrlTimingComputation function is not available in the I3C files .

But you can just define LL_I3C_CtrlBusConfTypeDef and add the parameters for the new timing : 

This mean, configure the parameters SDAHoldTime, WaitTime, SCLPPLowDuration, SCLI3CHighDuration, SCLODLowDuration, SCLI2CHighDuration, BusFreeDuration, BusIdleDuration in the LL_I3C_CtrlBusConfTypeDef structure through i3c Init structure.
Then call : 
HAL_I3C_Ctrl_BusCharacteristicConfig(I3C_HandleTypeDef *hi3c,const LL_I3C_CtrlBusConfTypeDef *pConfig); 

Foued