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Raspberry Pi 4 with Waveshare CAN/RS485 hat hangs with rainbow

I tried to set up my Raspberry Pi 4 with Waveshare CAN/RS485 hat for Venus OS, but it never booted up properly. I did not have an Mini-HDMI-Adapter to check the gui (initially). I tried different power supplies. SD card is Sandisk High Endurance 32GB.

This is what I found out:


- Plain Raspbian boots up completely, with CAN/RS485 hat connected. So SD card works, power supply seems to be OK as well.

- Venus OS release-candidate and Venus OS boot up properly if CAN/RS485 is NOT connected

- Venus OS does not boot up with CAN/RS485 hat connected. I got a HDMI-Adapter an see that it hangs with the rainbow square.


Any Ideas? Same behaviour with a second Raspberry Pi 4. I will now buy a used Raspberry Pi 2, and check what happens (and verify if the hat works at all or if it may have a defect).


Regards,

Thomas

Raspberry Pi
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kevgermany avatar image kevgermany ♦♦ commented ·
@tobox

Moved to modifications space where Pi questions belong.

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tobox answered ·

I purchased a used Raspberry Pi 2, with the same result. Venus OS runs properly without the hat, and hangs in the rainbow screen with the hat connected.


Here is a picture of the hat, shouldn't it be supported by Venus OS?


index.jpeg


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tobox answered ·

The hat seems to be OK. With raspbian and the appropriate config.txt changes, can0.0 shows up properly.


Any ideas?

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tobox answered ·

I'm getting closer. I attached a USB-TTL converter to TX and RX on the pi expansion port (pin 6+8) and saw the U-Boot prompt getting flooded with garbage, when the hat was attached.

I added termination to both buses, but that did not help. So I build a riser-module for the expansion port and left out the TX and RX pins.

The pi boots up properly.

I guess RS485 will not work now, but I have spare USB-RS485 converters that I can use.


index.jpeg


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