Two SPI devices, CAN Module with E-Ink Display - not working together

[gsivaych (Gaurav Singh Sivaych)]

Hi, I’ve been having problem using the two IO devices plugged together.

Hardware in use: RAK19011 + RAK19012 (dual io base board with power slot), RAK11200 (ESP core module), RAK13006 (CAN module) and RAK14000 (E-Ink display, buttons removed).

Based on link: CS on CAN module moved to WB_IO3. (de-soldered R9, shorted R16 pads)

Using RAK14000 (E-ink display) on IO slot A, RAK13006 (CAN module) on IO slot B. When plugged individually both work fine, when plugged together and example code flashed individually (appropriate CS pin, tried keeping the other one HIGH as well as LOW) - only E-ink display works, CAN module consistently throws configuration error 0x01. As soon as the E-ink Display is plugged out, the CAN device works fine.

Setup: Arduino IDE 2.3.2, BSP - RAKwireless ESP32 Boards 2.0.3

Intention is to use both together using their CS pins - read data over CAN and display on E-ink sequentially - like every minute or so.

[beegee (Bernd Giesecke)]

Welcome to the forum @gsivaych

The RAK14000 has a “special” SPI implementation that makes it incompatible with other SPI devices.

RAK14000 connects MISO and MOSI together (the display uses one line for in and out).

Only option is to cut MISO line on the RAK14000 by removing R6:

Location of R6:

[gsivaych (Gaurav Singh Sivaych)]

Thank you Bernd Giesecke, that worked as expected.
It would be really helpful if these things were included in documentation.