S32KのトピックGuidance on Using FlexCAN_Ip_ManualBusOffRecovery()

Guidance on Using FlexCAN_Ip_ManualBusOffRecovery()

saishanfi — Wed, 03 Sep 2025 05:46:24 GMT

Hi Team,

I have tested bus-off recovery with the following setup and need some clarification

In EB configuration, I selected Interrupt mode for bus-off recovery and disabled automatic bus-off recovery.

When I shorted CANL and CANH, the bus-off interrupt was triggered and handled via the Can_43_FLEXCAN_ProcessBusOffInterrupt()[SW32K3_S32M27x_RTD_4.4_4.0.0_P24 package] API.

For recovery, I periodically called the FlexCAN_IP_ManualBusOffRecovery() API.

During this test, I noticed that even though automatic bus-off recovery was disabled, the condition check inside the manual recovery API failed.

Could you please guide me the procedure for using FlexCAN_Ip_ManualBusOffRecovery().

Thanks & Regards,

Saishanfi

Re: Guidance on Using FlexCAN_Ip_ManualBusOffRecovery()

PetrS — Thu, 04 Sep 2025 13:37:25 GMT

Hi,

do not know HLD implementation much, but I think it does not offer API for doing manual recovery and you should not call low level function directly. Typically in AUTOSAR implementaitons user is going through via Can_SetControllerMode().

So implement the Can_ControllerBusOff() callback in your application and use Can_SetControllerMode() to transition the controller to CAN_T_STOP and then back to CAN_T_START after recovery.

BR, Petr

Re: Guidance on Using FlexCAN_Ip_ManualBusOffRecovery()

saishanfi — Thu, 04 Sep 2025 17:11:03 GMT

Hi @PetrS,

I have written a stub for manual Bus-Off recovery, and if recovery happens, I put the CAN controller into START mode using Can_43_FLEXCAN_setControllerMode(). However, recovery does not happen as expected.

Steps followed:

EB configuration: Interrupt mode for Bus-Off recovery enabled, automatic Bus-Off recovery disabled.
Shorted CANH and CANL → Bus-Off interrupt triggered and handled via Can_43_FLEXCAN_ProcessBusOffInterrupt() and controller mode was STOP.
Manual recovery stub uses a 10 ms recovery timer.

Observed behavior:

Shorted CANH/CANL for 3 seconds, then restored the bus.
After restoring:
- ESR1[FLTCONF] still shows Bus-Off.
- ESR1[SYNCH] is set (FlexCAN is synchronized to the CAN bus).

Questions:

After reconnecting CANH and CANL, recovery does not happen. When does ESR1[FLTCONF] clear? Does TEC need to drop below 256, or is it cleared automatically once the bus is restored?(In manual recovery mode)
Before putting the CAN controller into START mode, how can I check if the bus is ready to join or still in Bus-Off? Which bit should I check?

Could you please support on this?

Thanks &Regards,

Saishanfi