BB-SPIDEV0-00A0
(which is strange to me because I though the first digit was the SPI bus and I think P9_30 and P9_31 are SPI 1 and not SPI bus 0.)
You can’t totally rely on the numbering as Linux will number them as it sees fit,
unless you aliases them in place, as is sometimes seen in the device-tree.
You are however right in assuming that /dev/spidev[n].[m] means n = controller, m = channel.
By the way, did you ever get that data line to behave and hit zero volts as it’s supposed to?
@rlanders - It turns out that the reason the data line was just rippling and not going to zero is that the code was using the other data line! Once I connected the scope to the other line, the waveform was as expected when I wrote to the device. That was really the key to getting it to work.
Exactly the reason why I tend to suggest a standardized test-method like spidev_test.
It’s nothing personal, I just hate to search for bugs in peoples code…
@WalterCEden here they are… iCloud Drive - Apple iCloud