[国嵌攻略][170][摄像头驱动开发]

摄像头系统架构

V4L2 video for linux，专门为Linux系统定制的操作摄像头的规范。给应用程序提供访问摄像头统一的接口。相应的摄像头驱动也需要遵循V4L2规范。这样应用程序可以不根据硬件的不同而改变，提高应用程序的可移植性。

使能和测试摄像头驱动

make menuconfig ARCH=arm

device drivers-><*>multimedia support-><*>video for linux and [*]enable video for linux api 1

device drivers-><*>multimedia support->[*]video capture adapters->[*]v4l usb devices-><*>gspca based webcams-><*>zc3xx usb camera driver

make uImage ARCH=arm CROSS_COMPILE=arm-linux-

编译测试程序

修改dev_name = "/dev/video%d"为对应的设备文件名

arm-linux-gcc camera.c -o camera

还需要配置uboot

setenv bootargs noinitrd console=ttySAC0,115200 init=/linuxrc root=/dev/nfs rw nfsroot=192.168.1.101:.../rootfs,proto=tcp,nfsvers=3 ip=192.168.1.230:192.168.1.101:192.168.1.1:255.255.255.0::eth0:off
saveenv

vim board/samsung/mini2440/smdk2410.c

/* configure MPLL */

     writel((M_MDIV << 12) + (M_PDIV << 4) + M_SDIV,

            &clk_power->mpllcon);

     /* some delay between MPLL and UPLL */

     pll_delay(4000);

        pll_delay(4000);

   /* configure UPLL */

    writel((U_M_MDIV << 12) + (U_M_PDIV << 4) + U_M_SDIV,

            &clk_power->upllcon);

     /* some delay between MPLL and UPLL */

     pll_delay(8000);

     /* set up the I/O ports */

在MPLL和UPLL之间加了一个pll_delay(4000);

还需要配置kernel

[*]Networking support->Networking options->[*]IP: kernel level autoconfiguration and [*]IP: DHCP support and [*]IP:BOOTP support and [*]IP: RARP support

运行程序如果遇到EHCI USB主控器问题，可以修改相关的USB控制器配置。device drivers->[*]usb support-><*>EHCI HCD (usb 2.0) support or <*>OHCI HCD support