AWR1642: CANFD bus off recovery time too long after calling MCAN_Recovery

Dear  Jitendra:

Another question is that how can I get the realtime MCAN bus_off state? The cycle period for obtaining the status should be less than 30ms。

Thanks

Dear  Jitendra:

What can I do to reduce the bus off detection cycle? Can this be achieved？

Thanks

Dear  Jitendra:

By the way, is there any way to enable the MCAN auto recovery? I did not find any register to enable it.

Thanks

Now, I can enable the auto recovery by enable the Automatic Retransmission (DAR) Mode by set the MCAN_CCCR[6] DAR bit to 1;

but when the bus leave the bus off state, the data which is retransmiting will be sent immediately. 

Is there anyway to not really send this frame out on the premise that it can be detected?

Thanks

Dear  Jitendra:

Now I have some questions as follow:

1. How to ignore the retransmiting data in auto retransmit mode?

2. Is there any other way to enable the auto detect of the MCAN busoff?

(I only find enable auto retransmit can do this, but the time of the first frame is too short(about 8ms ± 2ms) )

Thanks

Dear  Jitendra:

In my tests, enabling retransmission reduces recovery time.

However, when busoff is removed, retransmitted frames are sent first (less than 10ms).

Is there a way to enable the retransmission mechanism without actually sending out this frame?

Thanks

Hi Shuang,

Here is response from the team on this e2e query-

1.Time taken by CAN FD to transition from bus off to error active state is around 1.42ms after INIT bit is de-asserted(0'b0) when there is no disturbance on the bus
i.e. CAN FD can see 129*11 recessive bits on the line

2.MCAN does not have auto bus on(ABO) bit i.e. the bus off to error active state transition cannot happen by IP itself.
INIT bit will have to be de-asserted by the processor based on the bus off interrupt. Transition to the bus off state can be known by enabling CAN interrupt and monitoring the bus off state in ISR
Select one of the interrupt by configuring ILE register. Enable the bus off interrupt by configuring IE[25]

3.Realtime bus off status can be seen in PSR[7] bit. You can poll the register. You can also enable the bus off interrupt if you do not intend to use polling

4.DCAN has the auto bus on(ABO) bit. By programming the counter for bus off recovery and setting the ABO bit, DCAN can transition from bus off to error active

5.When auto retransmission is enabled, time between 2 bus off states is 1.8ms i.e. when the first bus off occurs, de-assert the INIT bit to make a transition to the error active state.
As the retransmission is enabled MCAN starts transmitting the previous frame and it eventually goes to bus off

6.When auto retransmission is enabled, there is no way to ignore the previous frame. Same frame gets transmitted repeatedly

7.If auto retransmission is disabled, time between 2 bus off states is 162ms i.e. when the first bus off occurs, de-assert the INIT bit and send new packets continuously to take MCAN to bus off

Let me know if you have any further query or comment.

Regards,

Jitendra

Dear  Jitendra:

About your reply 3, I did not see the PSR[7] change realtime.

It can be set to 1 only I transfer the CAN data(call the send interface).

And the sequence it change can be influenced by the period of the data send.

I did not find which configuration can influence here. Is there any difference between my configuration and yours?

And my code of MCAN configuration is as below:

mcanCfgParams->fdMode = 0x1U;
mcanCfgParams->brsEnable = 0x1U;
mcanCfgParams->txpEnable = 0x0U;
mcanCfgParams->efbi = 0x0U;
mcanCfgParams->pxhddisable = 0x0U;
mcanCfgParams->darEnable = 0x1U;/* disable auto retransmit */
mcanCfgParams->wkupReqEnable = 0x1U;
mcanCfgParams->autoWkupEnable = 0x1U;
mcanCfgParams->emulationEnable = 0x0U;
mcanCfgParams->emulationFAck = 0x0U;
mcanCfgParams->clkStopFAck = 0x0U;
mcanCfgParams->wdcPreload = 0x0U;
mcanCfgParams->tdcEnable = 0x1U;
mcanCfgParams->tdcConfig.tdcf = 0U;
mcanCfgParams->tdcConfig.tdco = 8U;
mcanCfgParams->monEnable = 0x0U;
mcanCfgParams->asmEnable = 0x0U;
mcanCfgParams->tsPrescalar = 0x0U;
mcanCfgParams->tsSelect = 0x0U;
mcanCfgParams->timeoutSelect = CANFD_MCANTimeOutSelect_CONT;
mcanCfgParams->timeoutPreload = 0x0U;
mcanCfgParams->timeoutCntEnable= 0x0U;
mcanCfgParams->filterConfig.rrfe = 0x1U;
mcanCfgParams->filterConfig.rrfs = 0x1U;
mcanCfgParams->filterConfig.anfe = 0x3U;
mcanCfgParams->filterConfig.anfs = 0x3U;
mcanCfgParams->msgRAMConfig.lss = 127U;
mcanCfgParams->msgRAMConfig.lse = 64U;
mcanCfgParams->msgRAMConfig.txBufNum = 32U;
mcanCfgParams->msgRAMConfig.txFIFOSize = 0U;
mcanCfgParams->msgRAMConfig.txBufMode = 0U;
mcanCfgParams->msgRAMConfig.txEventFIFOSize = 0U;
mcanCfgParams->msgRAMConfig.txEventFIFOWaterMark = 0U;
mcanCfgParams->msgRAMConfig.rxFIFO0size = 64U;
mcanCfgParams->msgRAMConfig.rxFIFO0OpMode = 0U;
mcanCfgParams->msgRAMConfig.rxFIFO0waterMark = 0U;
mcanCfgParams->msgRAMConfig.rxFIFO1size = 64U;
mcanCfgParams->msgRAMConfig.rxFIFO1waterMark = 0U;
mcanCfgParams->msgRAMConfig.rxFIFO1OpMode = 0U;

mcanCfgParams->eccConfig.enable = 1;
mcanCfgParams->eccConfig.enableChk = 1;
mcanCfgParams->eccConfig.enableRdModWr = 1;

mcanCfgParams->errInterruptEnable = 1U;
mcanCfgParams->dataInterruptEnable = 1U;

Thanks

Dear  Jitendra:

Is there any difference between my config and yours?

Or is there any error config in my code can influence the busoff detect?

Thanks