MC9S12 CAN bus message transmit only once

[peteyo]

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

[danielmartynek]

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

[peteyo]

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)