I was attempting to use the ‘SPI0.1’ interface breakout with a Pico i.MX7D (It’s SPI3.1 on this board). After looking at the lines with a scope, I found that that flipping the order of the SPI worked (i.e. label ‘MOSI’ is actually CE1, ‘MISO’ is SCL, ‘SCL’ is MISO, and ‘CE1’ is actually MOSI). I conclude that the pins on the breakout are reversed from the labeling.
Is the schematic of the Rainbow HAT available? Is this a known errata?
UART and I2C on the breakout header worked as far as I tested them.