GPIO 接口测试分析和总结.docx

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DeviceDrivers–》GPIOSupport–》/sys/class/gpio

三、启动开发板

四、创建GPIO节点

echo24/sys/class/gpio/exportecho41/sys/class/gpio/export

五、设置GPIO方向

cd/sys/class/gpio/gpio24echooutdirection

cd/sys/class/gpio/gpio41echooutdirection

六、改变GPIO值

cd/sys/class/gpio/gpio24echo1value

cd/sys/class/gpio/gpio41echo1value

使用万用表测量VS子板–》JP1–》1或3管脚为高电平

cd/sys/class/gpio/gpio24echo0value

cd/sys/class/gpio/gpio41echo0value

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、FollowthesestepsforcontrollingtheGPIOlinesfromsysfsentries

a.Export,whichGPIOpinyouwanttocontrol.BelowstepsaredonewithrespecttoGPIO30(anexample

$echo30

$echo30/sys/class/gpio/export

b.ChangetheGPIOpindirectiontoin/out

$echoout/sys/class/gpio/gpio30/direction

$echoin/sys/class/gpio/gpio30/direction

c.Changingthevalue

$echo1/sys/class/gpio/gpio30/value

$echo0/sys/class/gpio/gpio30/value

d.UnexporttheGPIOpin

$echo30/sys/class/gpio/unexport

Sysfsentriesarecreatedfrom0-63incaseofDM816XbecauseithastwoGPIObanks0and1.

Note:GPIOswhichareusedalreadyinthedriverscannotbecontrolfromsysfs,unlessuntill

driverexportthatparticularpin.

RunthesecommandsforknowingwhataretheGPIOsalreadyrequestedinthedrivers.

$mount-tdebugfsdebugfs/sys/kernel/debug

$cat/sys/kernel/debug/gpio