STM32MP157C-DK2-＞Develop on Arm® Cortex®-A7之 C语言开发LED例程
编写C代码控制STM32MP157C-DK2开发板上的LD5以1s的时间间隔闪烁。
根据en.MB1272-DK2-C01_Schematic可以得知STM32MP157C-DK2开发板有两个GPIO口控制的LED灯，PA13和PA14，LED部分电路图如下：
例程使用PA14作为演示。
开发步骤可参考官方wiki教程
以STM32MP15-Ecosystem-v1.0.0开发包为例做讲解，步骤如下：
1.创建一个目录用于存放源代码
caiyong@caiyong-virtual-machine:/$ mkdir $HOME/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20
caiyong@caiyong-virtual-machine:/$ mkdir $HOME/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources2.为例程创建一个目录
caiyong@caiyong-virtual-machine:/$ mkdir $HOME/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example
caiyong@caiyong-virtual-machine:/$ cd $HOME/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example3.为例程创建一个源文件（led_toogle.c）
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example$ touch led_toogle.c
4.编写C代码
在Ubuntu桌面，通过文件进入led_toogle_example目录，选择led_toogle.c文件，然后右键用文本编辑器打开，如下图所示：
用文本编辑器打开led_toogle.c后，编写如下代码：
#include
#include
#include
#include
#include
#include
#include
#include
int main(int argc, char **argv)
{
struct gpiohandle_request req;
struct gpiohandle_data data;
char chrdev_name[20];
int fd, ret;
strcpy(chrdev_name, "/dev/gpiochip0");
/* Open device: gpiochip11 for GPIO bank A */
fd = open(chrdev_name, 0);
if (fd == -1) {
ret = -errno;
fprintf(stderr, "Failed to open %s\n", chrdev_name);
return ret;
}
/* request GPIO line: GPIO_A_14 */
req.lineoffsets[0] = 14;
req.flags = GPIOHANDLE_REQUEST_OUTPUT;
memcpy(req.default_values, &data, sizeof(req.default_values));
strcpy(req.consumer_label, "led_gpio_a_14");
req.lines = 1;
ret = ioctl(fd, GPIO_GET_LINEHANDLE_IOCTL, &req);
if (ret == -1) {
ret = -errno;
fprintf(stderr, "Failed to issue GET LINEHANDLE IOCTL (%d)\n",
ret);
}
if (close(fd) == -1)
perror("Failed to close GPIO character device file");
/* Start led blinking */
while(1) {
data.values[0] = !data.values[0];
ret = ioctl(req.fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &data);
if (ret == -1) {
ret = -errno;
fprintf(stderr, "Failed to issue %s (%d)\n",
"GPIOHANDLE_SET_LINE_VALUES_IOCTL", ret);
}
sleep(1);
}
/* release line */
ret = close(req.fd);
if (ret == -1) {
perror("Failed to close GPIO LINEHANDLE device file");
ret = -errno;
}
return ret;
} 然后关闭编辑器，选择保存。
5.为例程创建Makefile文件
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example$ touch Makefile
6.编写Makefile
在Ubuntu桌面，通过文件进入led_toogle_example目录，选择Makefile文件，然后右键用文本编辑器打开。用文本编辑器打开Makefile后，编写如下内容：
PROG = led_toogle
SRCS = led_toogle.c
CLEANFILES = $(PROG)
# Add / change option in CFLAGS and LDFLAGS
all: $(PROG)
$(PROG): $(SRCS)
$(CC) -o $@ $^ $(CFLAGS) $(LDFLAGS)
clean:
rm -f $(CLEANFILES) $(patsubst %.c,%.o, $(SRCS))然后关闭编辑器，选择保存。
7.编译工程
先回到主目录配置好SDK的环境变量：
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example$ cd /
caiyong@caiyong-virtual-machine:/$ cd $HOME/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package$ source SDK/environment-setup-cortexa7t2hf-neon-vfpv4-openstlinux_weston-linux-gnueabi
然后再进入到led_toogle_example目录编译工程（执行make指令即可）：
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package$ cd stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example/
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/D
oogle_examplecaiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example$ make
arm-openstlinux_weston-linux-gnueabi-gcc -march=armv7ve -mthumb -mfpu=neon-vfpv4 -mfloat-abi=hard -mcpu=cortex-a7 --sysroot=/home/caiyong/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/SDK/sysroots/cortexa7t2hf-neon-vfpv4-openstlinux_weston-linux-gnueabi -o led_toogle led_toogle.c -O2 -pipe -g -feliminate-unused-debug-types -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/D
oogle_examplecaiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example$
然后可以看到led_toogle文件夹下生成了名为led_toogle的可执行文件。
8.将生成的led_toogle可执行文件拷贝到开发板的/usr/local目录下
需要通过网络连接来执行文件的拷贝工作，有两种连接方式：
一种是通过USB来连接，电脑的USB口连接到开发板的CN7（USB）上，开发板作为RNDIS（USB以太网）功能，将显示出来的RNDIS网卡配置成192.168.7.90。（演示例程没有使用此方式，不做详细描述）
另一种是开发板通过网线连接到电脑所连接的路由器，路由器会为开发板分配一个IP地址，然后电脑通过此IP地址登录到开发板。（演示例程使用的是此方式，这样在开发时电脑可以上网）
将开发板连接到路由器，通过串口终端获取开发板的ip地址（在windows上使用SecureCRT）：
root@stm32mp1:~# ifconfig
eth0 Link encap:Ethernet HWaddr 00:80:E1:42:62:DB
inet addr:192.168.1.9 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::280:e1ff:fe42:62db/64 Scope:Link
inet6 addr: 2409:8a62:4b18:eae0:280:e1ff:fe42:62db/64 Scope:Global
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5276 errors:0 dropped:8 overruns:0 frame:0
TX packets:1611 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:410613 (400.9 KiB) TX bytes:259690 (253.6 KiB)
Interrupt:60 Base address:0x8000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:344 errors:0 dropped:0 overruns:0 frame:0
TX packets:344 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:22880 (22.3 KiB) TX bytes:22880 (22.3 KiB)
usb0 Link encap:Ethernet HWaddr 0A:45:40:76:76:B5
inet addr:192.168.7.2 Bcast:192.168.7.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
wlan0 Link encap:Ethernet HWaddr 10:98:C3:5E:F5:90
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)可以看到eth0的ip地址为192.168.1.9。
在Ubuntu的命令终端上执行命令拷贝文件：
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example$ scp led_toogle [email protected]:/usr/local/
led_toogle 100% 16KB 302.9KB/s 00:00
caiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/D
oogle_examplecaiyong@caiyong-virtual-machine:~/STM32MPU_workspace/STM32MP15-Ecosystem-v1.0.0/Developer-Package/stm32mp1-openstlinux-4.19-thud-mp1-19-02-20/sources/led_toogle_example$
9.在开发板上执行文件
通过串口终端进入开发板的usr/local目录，会发现led_toogle存在：
root@stm32mp1:~# cd /
root@stm32mp1:/# cd usr/local/
root@stm32mp1:/usr/local# ls
Cube-M4-examples Linux-A7-examples demo gtk_hello_world led_toogle lost+found weston-start-at-startup
root@stm32mp1:/usr/local# 执行led_toogle
root@stm32mp1:/usr/local# ./led_toogle 此时可以看到开发板上的LD5会1s闪烁一次。
停止执行可按Ctrl键+C键。
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