Neza-D1开发板学习之点灯篇
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板子到手先来点个灯那是少不了的，先确定LED接在哪个引脚上，查看原理图，发现LED的座位号是U13，原来不是普通的LED，是一颗单总线的WS2812灯珠，这颗LED是接在PC0引脚上的，引脚标有LEDC-DO，是接在了LED控制器上，驱动官方已经做好了，我们直接用就可以
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下边废话不多说，来看一下系统启动过程，系统已经把驱动给加载好了
[ 2.100847] sunxi_led_probe()1715 - start [ 2.105375] sunxi_get_str_of_property()1560 - failed to get the string of propname led_regulator! [ 2.115306] sunxi_register_led_classdev()1448 - led_classdev start [ 2.126681] sunxi_led_probe()1820 - finish -
来查看一下LED子系统下的灯
# ls /sys/class/leds/ blink sunxi_led11g sunxi_led3b sunxi_led5r sunxi_led8g sunxi_led0b sunxi_led11r sunxi_led3g sunxi_led6b sunxi_led8r sunxi_led0g sunxi_led1b sunxi_led3r sunxi_led6g sunxi_led9b sunxi_led0r sunxi_led1g sunxi_led4b sunxi_led6r sunxi_led9g sunxi_led10b sunxi_led1r sunxi_led4g sunxi_led7b sunxi_led9r sunxi_led10g sunxi_led2b sunxi_led4r sunxi_led7g sunxi_led10r sunxi_led2g sunxi_led5b sunxi_led7r sunxi_led11b sunxi_led2r sunxi_led5g sunxi_led8b这里出现了很多LED，设备树默认是12个，这样子是不是很熟悉了，我们板子上的LED就是led0
# ls /sys/class/leds/sunxi_led0b/ brightness power uevent device subsystem waiting_for_supplier max_brightness trigger先来个红色的呼吸灯
# echo heartbeat > /sys/class/leds/sunxi_led0r/trigger再来个蓝色1秒闪烁一次
# echo timer > /sys/class/leds/sunxi_led0b/trigger这灯真是亮瞎眼啊，查看亮度
# cat /sys/class/leds/sunxi_led0b/brightness 255调到50,这下好了
# echo 50 > /sys/class/leds/sunxi_led0b/brightness把灯关掉
# echo none > /sys/class/leds/sunxi_led0b/trigger查看支持哪些触发方式
# cat /sys/class/leds/sunxi_led0b/trigger none rc-feedback rfkill-any rfkill-none kbd-scrolllock kbd-numlock kbd-capslock kbd-kanalock kbd-shiftlock kbd-altgrlock kbd-ctrllock kbd-altlock kbd-shiftllock kbd-shiftrlock kbd-ctrlllock kbd-ctrlrlock mmc0 mmc1 timer oneshot [mtd] nand-disk heartbeat backlight gpio cpu cpu0 activity default-on transient netdev pattern audio-mute audio-micmute -
当然以上的操作不是操作的GPIO，而是使用的LED子系统，下边是用GPIO操作LED，这里的LED是在扩展板上引出的，引脚是通过PCF8574扩展出来的，具体可以看看D1原理图
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使用SYSFS方式操作GPIO，在操作前先查看一下系统里未使用的GPIO，这里以PD18 BL—PWM为例# ls /sys/class/gpio/ export gpiochip0 gpiochip2020 unexport # PD18 = 32*3+18=114 # echo 114 > export执行成功 目录下会出现gpio114,查看一下内容，可以看到里边有direction，value
# ls gpio114 active_low edge uevent device power value direction subsystem waiting_for_supplier接下来设置方向
# echo out > gpio114/direction输出高电平
# echo 1 > gpio114/value输出低电平
# echo 0 > gpio114/value不用的话执行
# echo 114 > unexport查看一下，已经没有那个引脚导出的目录了
# ls export gpiochip0 gpiochip2020 unexport -
使用GPIOD操作GPIO，先查询一下系统GPIO情况# gpiodetect gpiochip0 [2000000.pinctrl] (224 lines) gpiochip1 [pcf8574] (8 lines) # gpioinfo gpiochip0 | grep -v unused | grep -v kernel gpiochip0 - 224 lines: line 0: unnamed "sysfs" input active-high [used] line 1: unnamed "sysfs" input active-high [used] line 5: unnamed "sysfs" input active-high [used] line 34: unnamed "interrupt" input active-high [used] line 110: unnamed "soc@3000000:rotary" input active-low [used] line 111: unnamed "soc@3000000:rotary" input active-low [used] line 115: unnamed "usb1-vbus" output active-high [used] line 116: unnamed "otg_det" input active-high [used] line 117: unnamed "otg_id" input active-high [used] line 118: unnamed "soc@3000000:ir_send" output active-high [used] line 144: unnamed "phy-rst" output active-high [used] line 166: unnamed "cd" input active-high [used] # gpioinfo gpiochip1 gpiochip1 - 8 lines: line 0: unnamed "Key volume up" input active-low [used] line 1: unnamed "Key volume down" input active-low [used] line 2: unnamed "Key back" input active-low [used] line 3: unnamed "blink" output active-low [used] line 4: unnamed "Key enter" input active-low [used] line 5: unnamed "led" output active-high [used] line 6: unnamed "reset" output active-low [used] line 7: unnamed "dc" output active-low [used]同样使用上边那个未使用的引脚为例 PD18 BL-PWM
输出高电平# gpioset gpiochip0 114=1输出低电平
# gpioset gpiochip0 114=0读取引脚电平
# gpioget gpiochip0 114 1就这么简单
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以上操作还都未涉及到代码，下边开始用代码操作GPIO,代码仅供参考
SYSFS方式#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> int main(void) { FILE *p = NULL; int i = 0; p = fopen("/sys/class/gpio/export", "w"); fprintf(p, "%d", 38); fclose(p); p = fopen("/sys/class/gpio/gpio38/direction", "w"); fprintf(p, "out"); fclose(p); for (i = 0; i < 100; i++) { p = fopen("/sys/class/gpio/gpio38/value", "w"); fprintf(p, "%d", 1); sleep(1); fclose(p); p = fopen("/sys/class/gpio/gpio38/value", "w"); fprintf(p, "%d", 0); sleep(1); fclose(p); } p = fopen("/sys/class/gpio/unexport", "w"); fprintf(p, "%d", 38); fclose(p); return 0; }GPIOD方式#include "gpiod/gpiod.h" #include <linux/fcntl.h> #include <signal.h> #include <stdio.h> -std=c99 -std=gnu99 #include <stdlib.h> #include <string.h> #include <sys/time.h> #include <unistd.h> #define LED_PIN 148 PD8 32*3+18 #define msleep(t) usleep((t)*1000) struct gpiod_chip *chip; struct gpiod_line *line; void _timer_handler(int n) { num++; gpiod_line_set_value(line, num % 2); } int main(int argc, char const *argv[]) { struct gpiod_line_request_config config; int req; /* 1.打开 GPIO 控制器 */ chip = gpiod_chip_open("/dev/gpiochip0"); if (!chip) return -1; /* 2.获取指定引脚 */ line = gpiod_chip_get_line(chip, LED_PIN); if (!line) { gpiod_chip_close(chip); return -1; } /* 3.配置引脚输出 */ req = gpiod_line_request_output(line, "blink", 0); if (req) { fprintf(stderr, "gpio line request error.\n"); return -1; } signal(SIGALRM, _timer_handler); struct itimerval itv; itv.it_value.tv_sec = 1; itv.it_value.tv_usec = 1000; itv.it_interval.tv_sec = 1; itv.it_interval.tv_usec = 0; setitimer(ITIMER_REAL, &itv, NULL); while (1) { } return 0; } -
到此点灯结束，感谢观看！
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