Posted on March 30, 2018 at 14:48 I'm testing one application with 3 differente device that send a message with random command ID and random data on CAN bus every random timeout: two devices with two STM32L433 nucleo and one with STM32F446 nucleo and with TJA1044T NXP transceivers.
I implemented firmware starting with STMCube (rev. 4.0) and added my application code with all corrections that I found in the community.
For first test the command ID random range was between 0 to 50 and the timeout random range was from 10ms to 1s. In this case all work enough fine without errors or packet lost.
In second test I reduced the timeout random range and was between 1ms to 10ms. In this case some errors appear and some packet lost; In particular the most freqeuntly errors was BIT ERROR (BR error).
To stress the application again I reduced the command ID random range to 1 (only command ID 0) and set the timeout to 1ms fixed: every ms all the boards (not sincronized) send the same command ID. In this case the number of errors (BOF, STF, FOR, ACK BR and BD) and lost packets increase a lot.
To evaluate the number of errors and lost packets, I implemented specific counters
that I can read by PC SerialPort when the test is stoped.
The frequency of CAN bus is 1Mbit/s, I calculated the timing by
/external-link.jspa?url=http%3A%2F%2Fwww.bittiming.can-wiki.info%2F
(Tq = 5ns, BS1 = 13, BS2 = 2, SJW = 1) and I used a very short cable (about 30cm).
In alltests the number of sent packet by every board are about 000.
My question is: is normal this behavior? I didn't found materials in intertet about this.
#can #stm32f4 #stm32l4
Note: this post was migrated and contained many threaded conversations, some content may be missing.
