Hey Joe,

spi0 on my BBGW also gave me the wrong result when I ran the spi test code 
by shorting p18 and p21. How did you solve your problem? Replace the 
cap???? 

On Tuesday, November 15, 2016 at 6:58:35 AM UTC+8, Joe Phaneuf wrote:
>
> 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!
>

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