S12 / MagniV MicrocontrollersのトピックRe: MC9S12 CAN bus message transmit only once

MC9S12 CAN bus message transmit only once

peteyo — Mon, 19 Nov 2018 03:09:20 GMT

Hi,

I did a test with multi-CAN devices, and the S12 transmitted message per 250ms.

I obtained there is no ACK slot on waveform(no one received this message), thus the message was re-send again and again(the interval became only 1ms since message was re-sent nonstop).

I just want to know if there is a bit setting in register to ignore ACK or transmit only once, so that i can keep my message cycle time in 250ms.

thanks

Re: MC9S12 CAN bus message transmit only once

danielmartynek — Wed, 21 Nov 2018 15:00:41 GMT

Hi,

This is required by the CAN standard.

You can refer to: https://www.nxp.com/files/microcontrollers/doc/data_sheet/BCANPSV2.pdf

Regards,

Daniel

Re: MC9S12 CAN bus message transmit only once

peteyo — Thu, 22 Nov 2018 02:47:02 GMT

Hi Daniel,

I found a setting as below and it seems like this setting could stop retransmission even there is an error or non-ACK situation. If I schedule a 250ms cycle time transmission with setting these bits high and then remove other devices on the bus(only one device on the bus), the CAN bus signals would keep in 250ms.(sometimes loss but no retransmission)