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LPCXpresso 11C24 to RPi CAN communication

Question asked by Thomas Brijs on May 16, 2019
Latest reply on Jun 28, 2019 by jeremyzhou

Hi,

 

i am trying to setup 2-way communication between an LPCXpresso 11C24 and a raspberry pi with PiCAN2 HAT.

When i run the cansniffer on the Pi and run the nxp_lpcxpresso_11c24_periph_ccan_rom example program I don't see any traffic so i'm checking to see where it might've gone wrong. I run the axf binary with 'Debug As' - 'MCUXpresso IDE Linkserver (incl. CMSIS-DAP) probes'.

I can use  external 12V bus supply on the Pi but that doesn't change anything.

I'm using an external 5V supply (from the Pi which can pull 1A) on the can interface of the LPCXpresso (JP4 header).

The Pi has an on-board termination resistor which i have connected.

I see there is 60Ohms + 60Ohms between CAN_H and CAN_L on the LPCXpresso board with a 1nF to filter HF, does this count as a 120Ohms termination resistor or do I need to add one externally (i think not)?

I also tried it with  an extra 120Ohms resitor on the LPC side but it didn't change anything.

I use a Cat5 twisted pair cable.

LPC sides use 500000bytes/s baudrate and RPi side 500000 BITrate

I suspect 1 baud equals 1 bit in this case (i know the differrence between baud and bit)

 

Is there anything else I need to check before I can read the TEST message that is sent from the LPC?

 

attached a picture of my setup, the breadboard is only there for the 5V from Pi ->  LPC (the led without resistor  just shows theres +5V)

 

also bear in mind I don't have a scope or logic analyzer here..

 

Thanks in advance!

 

Best regards,

 

Thomas

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