用攒电脑的办法快速玩转arm linux

3万 · 2013-9-4 14:44

禁用hdmi,这个跟spi冲突
BeagleBoneBlack Cape Manager
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To display the overlays currently enabled by the cape manager, type:

cat /sys/devices/bone_capemgr.*/slots

On a default Beaglebone Black, it should show:

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

The format of output is:

Slot Number:
Slot I2C Client Address:
[P]robed Flag
Probe [F]ailed Flag
[O]verride Flag
[l]oading Flag
[L]oaded Flag

Capes can be forcibly enabled or disabled by passing the following parameters to the kernel during boot:

capemgr.enable_partno=BB-CAPENAME
capemgr.disable_partno=BB-CAPENAME

Kernel parameters can be specified in the uEnv.txt file.

For example, if you want to disable the HDMI interface to free up I/O, mount the FAT partition found on the onboard eMMC where the uEnv.txt file is located:

mount /dev/mmcblk0p1 /media/card

Add add the following to the uEnv.txt file:

optargs=quiet capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN

BB-BONELT-HDMI is the on-board HDMI interface. BB-BONELT-HDMIN is the same interface but with no audio. If only the BB-BONELT-HDMI interface overlay is disabled, the BB-BONELT-HDMIN is loaded instead hence the requirement to disable both.

Then umount and reboot the bone.

Now, when the list of overlays are displayed, the Bone-Black-HDMI & Bone-Black-HDMIN interfaces are shown as not loaded (L):

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-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN

3万 · 2013-9-4 15:29

./spidev_test
-bash: ./spidev_test: No such file or directory
root@arm:~# gcc
-bash: gcc: command not found
root@arm:~# apt-get install gcc

3万 · 2013-9-4 15:29

fter this operation, 44.0 MB of additional disk space will be used.
Do you want to continue [Y/n]? y

3万 · 2013-9-4 15:44

cat /proc/version
Linux version 3.8.13-bone26 (root@imx6q-wandboard-2gb-0) (gcc version 4.7.3 (Ubu
ntu/Linaro 4.7.3-1ubuntu1) ) #1 SMP Sat Aug 17 00:43:59 UTC 2013
root@arm:~# cat /etc/issue
Ubuntu 13.04 \n \l

root@arm:~# ./spidev_test
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
root@arm:~#
root@arm:~# uname -a
Linux arm 3.8.13-bone26 #1 SMP Sat Aug 17 00:43:59 UTC 2013 armv7l armv7l armv7
终于正常了。。。测试方法是把spi_out spi_in 连接起来。发出的和回读的数据一致了。