GPIO 接口测试
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GPIO接口测试步骤
一、设置硬件环境
连接VS子板从dm8168扩展出来的GPIO连接到了VS子板的J1接口
二、配置编译linux内核
1》在linux-2.6.37-psp04.00.00.12/arch/arm/mach-omap2/ board-ti8168evm.c文件的558行添加TI816X_MUX(SC1_DATA, OMAP_MUX_MODE2),
TI816X_MUX(SC0_DET, OMAP_MUX_MODE2),
配置GP0[24] GP1[9]管脚为GPIO管脚
2》配置linux内核使能Device Drivers –》GPIO Support –》/sys/class/gpio
三、启动开发板
四、创建GPIO节点
echo 24 > /sys/class/gpio/export
echo 41 > /sys/class/gpio/export
五、设置GPIO方向
cd /sys/class/gpio/gpio24
echo "out" > direction
cd /sys/class/gpio/gpio41
echo "out" > direction
六、改变GPIO值
cd /sys/class/gpio/gpio24
echo 1 > value
cd /sys/class/gpio/gpio41
echo 1 > value
使用万用表测量VS子板–》JP1 –》1 或3管脚为高电平
cd /sys/class/gpio/gpio24
echo 0 > value
cd /sys/class/gpio/gpio41
echo 0 > value
使用万用表测量VS子板–》JP1 –》1 或3管脚为低电平
七、运行C测试程序
运行gpio0-24-test 或gpio1-9-test测试例程,使用示波器可以看到频率为1HZ的方波
一、Follow these steps for controlling the GPIO lines from sysfs entries
a. Export, which GPIO pin you want to control. Below steps are done with respect to GPIO30 (an example
$ echo 30 > /sys/class/gpio/export
b. Change the GPIO pin direction to in/out
$ echo "out" > /sys/class/gpio/gpio30/direction
$ echo "in" > /sys/class/gpio/gpio30/direction
c. Changing the value
$ echo 1 > /sys/class/gpio/gpio30/value
$ echo 0 > /sys/class/gpio/gpio30/value
d. Unexport the GPIO pin
$ echo 30 > /sys/class/gpio/unexport
Sysfs entries are created from 0 - 63 in case of DM816X because it has two GPIO banks 0 and 1.
Note: GPIO's which are used already in the drivers can not be control from sysfs, unless untill driver export that particular pin.
Run these commands for knowing what are the GPIO's already requested in the drivers.
$ mount -t debugfs debugfs /sys/kernel/debug
$ cat /sys/kernel/debug/gpio。