pdp7/beaglebone-spidev-test.md

## beaglebone-spidev-test.md

      
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SPI0: Connect wire from P9_18 and P9_21
SPI1: Connect wire from P9_29 and P9_30
Pins: http://beagleboard.org/static/images/cape-headers-spi.png

/boot/uEnv.txt

uname_r=4.4.39-ti-r79
cmdline=coherent_pool=1M quiet cape_universal=enable
cape_enable=bone_capemgr.enable_partno=cape-universala

config-pin

for i in 17 18 19 20 21 22 28 29 30 31 42; 
do echo config-pin P9.$i spi;
done

config-pin P9.17 spi
config-pin P9.18 spi
config-pin P9.19 spi
config-pin P9.20 spi
config-pin P9.21 spi
config-pin P9.22 spi
config-pin P9.28 spi
config-pin P9.29 spi
config-pin P9.30 spi
config-pin P9.31 spi
config-pin P9.42 spi

spidev_test:

Source: https://raw.githubusercontent.com/torvalds/linux/master/tools/spi/spidev_test.c
debian@beaglebone:~/spi$ sudo ./spidev_test --device /dev/spidev1.0
spi mode: 0
bits per word: 8
max speed: 500000 Hz (500 KHz)

FF FF FF FF FF FF 
40 00 00 00 00 95 
FF FF FF FF FF FF 
FF FF FF FF FF FF 
FF FF FF FF FF FF 
DE AD BE EF BA AD 
F0 0D 
debian@beaglebone:~/spi$ sudo ./spidev_test --device /dev/spidev1.1
spi mode: 0
bits per word: 8
max speed: 500000 Hz (500 KHz)

FF FF FF FF FF FF 
40 00 00 00 00 95 
FF FF FF FF FF FF 
FF FF FF FF FF FF 
FF FF FF FF FF FF 
DE AD BE EF BA AD 
F0 0D 
debian@beaglebone:~/spi$ sudo ./spidev_test --device /dev/spidev2.0
spi mode: 0
bits per word: 8
max speed: 500000 Hz (500 KHz)

FF FF FF FF FF FF 
40 00 00 00 00 95 
FF FF FF FF FF FF 
FF FF FF FF FF FF 
FF FF FF FF FF FF 
DE AD BE EF BA AD 
F0 0D 
debian@beaglebone:~/spi$ sudo ./spidev_test --device /dev/spidev2.1
spi mode: 0
bits per word: 8
max speed: 500000 Hz (500 KHz)

FF FF FF FF FF FF 
40 00 00 00 00 95 
FF FF FF FF FF FF 
FF FF FF FF FF FF 
FF FF FF FF FF FF 
DE AD BE EF BA AD 
F0 0D 

Adafruit_BBIO SPI test

test-spi.py

from Adafruit_BBIO.SPI import SPI

# From Adafruit Learning System:
# https://learn.adafruit.com/setting-up-io-python-library-on-beaglebone-black/spi     
#spi = SPI(bus, device) #/dev/spidev<bus>.<device>
#spi = SPI(0,0)	#/dev/spidev1.0
#spi = SPI(0,1)	#/dev/spidev1.1
#spi = SPI(1,0)	#/dev/spidev2.0
#spi = SPI(1,1)	#/dev/spidev2.1

spi = SPI(0,0) 
print spi.xfer2([32, 11, 110, 22, 220]) 
spi.close() 

output

debian@beaglebone:~/spi$ sudo python test-spi.py 
[32, 11, 110, 22, 220]

strace

debian@beaglebone:~/spi$ sudo strace -e open -f python ./test-spi.py 2>&1 |grep /dev/spidev
open("/dev/spidev1.0", O_RDWR|O_LARGEFILE) = 3