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Legacy microcontrollers Forum Discussions

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Hi People,

I am bit new to XMC4500 relax lite kit environment. I want to read CAN bus signals onto microcontroller. Could some one please let me know the basic structure of how I would be able to do this.

Kind Regards
Nandish
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Hi Nandishnan,

I have read CANbus with arduino and ChipKIT, so I have some experience. But I only just received my Relax Lite kit and am researching myself. If you haven't yet experience experimenting with CAN, I will go over what worked for me. I started with an ODB diagnostic tool and an auto that uses CANbus and then attempted to connect my circuit in the middle. As far as I know, the Relax Lite only has CAN controller and not CAN transceiver, so the CAN-H and CAN-L signals cannot be connected to the CAN-Rx and CAN-Tx TTL pins. Most engineers will now purchase a Ti, NXP, or Microchip CAN transceiver IC and use that to "talk" to the MCU from the CANbus.

There are sample analog designs for implementing a CAN transceiver, however, today, no one "tries" these things and just buys the chip. If the XMC4500 has programmable blocks like the Cypress PSoC, it is possible you can program a differential amplifier (that is an op-amp) to be the CAN transceiver. I would be very happy if this were at all possible in the XMC, as that would mean less chips required externally. For my current design project, if I can at all get away without needing additional PCBs made, that is "priceless".

OK, so back to using CAN transceiver to see CANBUS...
1399.attach

You may or may not also need a 85-120 ohm resistor across CAN-H and CAN-L. The "end" nodes on a CANbus are supposed to be terminated, however, when dealing with other peoples' equipment, it is best to have the capability to use or not use resistance. This is part of why engineers buy ready-made ICs, as they come with amazing specs where their engineers have already worked out all the little problems with implementing your own differential amplifier...

Thanks,
Chris
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Hi un3x!

Did You manage to get it running in the meantime?
Could You eventually please share the results with us?

Thanks!
Robert
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