Beaglebone Black - Enable SPI Interface

2
votes

I'm looking to use the MAX31865 (http://www.maximintegrated.com/datasheet/index.mvp/id/7963) with my Beaglebone Black running Ubuntu 12.0.4. The kernel is a standard 3.8.13-bone30 kernel. Having an SPI interface, I was hoping to interface with the development kit using SPI0 on the Beaglebone Black. Unfortunately every time I enter

ls /dev/spi*

the result is

ls: cannot access /dev/spi*: No such file or directory

I attempted to follow the directions here: http://hipstercircuits.com/enable-spi-with-device-tree-on-beaglebone-black-copy-paste/

When I copied the compiled file over to /lib/firmware I noticed that there were three other spi related files. Those are

BB-SPIDEV0-00A0.dtbo
BB-SPIDEV1-00A0.dtbo
BB-SPIDEV1A1-00A0.dtbo

In addition, the command

echo BB-SPI1-01 > /sys/devices/bone_capemgr.*/slots

returns

bash: echo: write error: No such file or directory

I've tried the same in Angstrom with no success. Can anyone assist me in getting the SPI interface working? Thanks!

3
spibeagleboneblack

3 Answers

4
votes

In your case, you should only use the file names appeared in the dir. For example instead of "BB-SPI1-01", you should use "BB-SPIDEV0" or "BB-SPIDEV1" ... etc Also don't forgot to replace the * in "bone_capemgr.*" with a number, it's 8 for me.

here are my steps: 1) 

root@beaglebone:/# cat /sys/devices/bone_capemgr.8/slots
0: 54:PF---
1: 55:PF---
2: 56:PF---
3: 57:PF---  
4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G  
5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI

notice, there are only 0-5 items

2) cd to the /lib/firmware folder

root@beaglebone:/lib/firmware# ls *SPI*
ADAFRUIT-SPI0-00A0.dtbo  BB-SPIDEV0-00A0.dts   BB-SPIDEV1A1-00A0.dtbo
ADAFRUIT-SPI1-00A0.dtbo  BB-SPIDEV1-00A0.dtbo  BB-SPIDEV1A1-00A0.dts
BB-SPIDEV0-00A0.dtbo     BB-SPIDEV1-00A0.dts   BBB_SPI0-00A0.dtbo
root@beaglebone:/lib/firmware# echo BBB_SPI0 > /sys/devices/bone_capemgr.8/slots

3) cat slots

root@beaglebone:/lib/firmware# cat /sys/devices/bone_capemgr.8/slots
0: 54:PF---
1: 55:PF---
2: 56:PF---
3: 57:PF---
4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
7: ff:P-O-L Override Board Name,00A0,Override Manuf,BBB_SPI0

Notice that there're now a new item 7, which is recently added.

4)now the device is there:

root@beaglebone:/lib/firmware# ls /dev/spi*
/dev/spidev1.0

If there's anything wrong in between, please post your error messages.

0
votes

This is because the HDMI uses the pins (28-31 on the P9 header) and hence, these pins are not available unless the HDMI DTS is

0
votes
  • step 1 : cd /lib/firmware
  • step 2 : cd /sys/devices/bone_capemgr.8/
  • step 3 : cat slots (checking purpose)
  • step 4 : echo BB-SPIDEV0 > slots
  • step 5 : cat slots