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STM32f042 CAN attempt

Question asked by fred bar on Aug 15, 2017

Hello.

I am using a stm32F042 for some CAN communications, alongside a SN65HVD230 as transceiver.

I have two boards (my own) using both those ICs.

I made a simple program, based on the STM32 example, from a STMCube initial code.

Actually, i have problems making my two modules discussing. Sending « works » (in the way that the can outputs things), but receiving does not.

I’ll go into code later eventually, but i first have a question about what the STM32F outputs. Please see the CAN oscilloscope trace below. CAN_L and CAN_H signals are cyan and yellow, blue is what comes out of the transceiver on receiving side.

This signal is generated, then the sender enters timeout. It seems there are a dozen attempts, then a burst of much shorter pikes. 

What bothers me is that i cannot relate this signal to anything i could gather from docs, like the CAN frame description.. https://upload.wikimedia.org/wikipedia/commons/5/5e/CAN-Bus-frame_in_base_format_without_stuffbits.svg

 

At the moment, i do believe the receiver does not understand the data that is sent, as it looks like garbage to me.

 

Any idea, please?

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