TMS570LS3134: Auto-bus-on abort

Koichiro Tashiro

Part Number: TMS570LS3134

Hi,

I have a question from my customer regarding below TRM description.
At section 24.17.8 Auto-Bus-On Time Register (DCAN ABOTR) in SPNU499B, there is a NOTE saying;

On write access to the CAN Control register while Auto-Bus-On timer is running, the Auto-Bus-On procedure will be aborted.

I understood Auto-Bus-On feature is aborted if above case happens.
What is an expected recovery sequence from this situation in customer code?

Thanks and regards,
KoT

over 5 years ago

0 QJ Wang over 5 years ago

TI__Guru**** 186196 points

Hello KoT,

On write access to the CAN Control register while Auto-Bus-On timer is running, the Auto-Bus-On procedure will be aborted.

The customer needs to manually set init bit in control register. When the Init bit is cleared by the application again, the module will then wait for 129
occurrences of Bus Idle (129 × 11 consecutive recessive bits) before resuming normal operation.

0 Koichiro Tashiro over 5 years ago in reply to QJ Wang

TI__Mastermind 21140 points

Hi QJ,

So, customer needs to manually set Init bit once, then reset Init bit afterward ?

In this case, CPU needs to know when Auto-Bus-On procedure is aboarted by register access.
Is this nortified to CPU?

Thanks and regards,
KoT

0 QJ Wang over 5 years ago in reply to Koichiro Tashiro

TI__Guru**** 186196 points

Hi KoT,

If Bus-Off-Recovery is not done, the module will stay in Bus-Off state. There is no other notification.

0 Koichiro Tashiro over 5 years ago in reply to QJ Wang

TI__Mastermind 21140 points

Hi QJ,

I see.
So CPU should periodically check BOff bit in DCAN ES resister, then if the module stays in Bus-Off state too long,
CPU needs to try the recovery sequence (manually set Init bit then reset it).

Is this correct?

Thanks and regards,

KoT

0 QJ Wang over 5 years ago in reply to Koichiro Tashiro

TI__Guru**** 186196 points

Hi KoT,

When you get Bus-Off interrupt, it's better not to write data to the control register until it is recovered

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TMS570LS3134: Auto-bus-on abort