Hey, cross posting from seeed studio forums.
tldr: clocking in data on spi0 looks cattywompus, spi1 ok Was noticing an issue with some custom hardware/software that utilizes both spi channels, was working on beaglebone black prior. Wanted to make it easily reproducible so flashed a bbgw and used adafruit bbio library as an example. steps: 1.) flash BBGW with latest production image 4.4.15-ti-r37 (other kernel versions and imaged used as well) 2.) prevent sound drivers from loading, as they conflict with spi1: cd /lib/modules/4.4.15-ti-r37/kernel/sound/core mv snd.ko snd.ko.bkp 3.) install adafruit library from source (need latest greatest, pip upgrade didn't work) cd ~ git clone https://github.com/adafruit/adafruit-beaglebone-io-python.git cd adafruit-beaglebone-io-python python setup.py install cd .. 4.) reboot 5.) use wires to loopback MOSI to MISO, both channels short P9.18 and P9.21 with a piece of wire (SPI0) short P9.29 and P9.30 with a piece of wire (SPI1) 6.) put the following into a file and run it from Adafruit_BBIO.SPI import SPI def run(x,y): print 'running spi {} {}'.format(x,y) spi = SPI(x,y) spi.mode=2 spi.msh=4000000 bytes2send = range(20) print 'sending {}'.format(bytes2send) print spi.xfer2(bytes2send) spi.close() run(0,0) run(1,0) result: sending [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19] [128, 7, 28, 31, 112, 231, 124, 127, 192, 135, 156, 159, 240, 231, 252, 255, 0, 7, 28, 31] running spi 1 0 sending [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19] [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19] so, spi1 works in loopback. spi0...wtf? there are places where it looks like it's double clocking MISO (like a 0x00000001 becomes a 0x00000011), some of it just looks random. Works fine on beaglebone black. Thoughts? If anyone has spi0 working on a bbgw would love to hear about the setup. Thanks! -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/83280ea1-4688-4f88-a1eb-f82e512a71c8%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.