beaglebone-spidev-test

beaglebone-spidev-test.md

Loopback

• 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

in the latest kernel 4.4.12

for i in 17 18 19 20 21 22 28 29 30 31 42;
do echo config-pin P9.$i spi;
done
no longer works.

for spidev1.0
config-pin P9.17 spi_cs
config-pin P9_18 spi
config-pin P9_21 spi
config-pin P9.22 spi_sclk

for spidev2.0
config-pin P9.31 spi_sclk
config-pin P9.28 spi_cs
config-pin P9.30 spi
config-pin P9.29 spi

I tried the above steps but did not work in my case. Here is the log :
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 KHz)
Could you help me?

@VarunPwr I think you might have solved this already. But if not, you can add the --verbose option to see the TX/RX buffer.

@VarunPwr I think you might have solved this already. But if not, you can add the --verbose option to see the TX/RX buffer.

debian@beaglebone:~/tmp$ sudo ./a.out --device /dev/spidev2.1 --verbose
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 KHz)
TX | 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 F0 0D |......@.........................|
RX | 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................................|

Hello if people are still having issues please open an issue in
https://github.com/adafruit/adafruit-beaglebone-io-python/

thanks!

Hello if people are still having issues please open an issue in
https://github.com/adafruit/adafruit-beaglebone-io-python/

thanks!

Thanks a lot, it works now!