Neza-D1开发板学习之按键和旋转编码器篇

1. Neza-D1开发板上只引出一个按键，是使用的LRADC检检测按键的，想使用更多按键，可以使用板子上通过PCF8574扩展出来的IO，我画的扩展板使用了四个按键，分别为PP0，PP1，PP2，PP4

   

2. 设备树配置如下 内核需要勾选 Polled input device skeleton
   gpio_keys {
   compatible = “gpio-keys”;
   pinctrl-names = “default”;
   /pinctrl-0 = <&key_pins>;/
   #address-cells = <1>;
   #size-cells = <0>;
   autorepeat;
   button@0 {
   label = “Key volume up”;
   linux,code = ;
   gpios = <&pcf8574 0 GPIO_ACTIVE_LOW>; /* PP0 /
   };
   
   button@1 {
   label = “Key volume down”;
   linux,code = ;
   gpios = <&pcf8574 1 GPIO_ACTIVE_LOW>; / PP1 /
   };
   
   button@2 {
   label = “Key back”;
   linux,code = ;
   gpios = <&pcf8574 2 GPIO_ACTIVE_LOW>; / PP2 /
   };
   
   button@3 {
   label = “Key enter”;
   linux,code = ;
   gpios = <&pcf8574 4 GPIO_ACTIVE_LOW>; / PP4 */
   };
   
   };

3. 编码器接在D1的PD14 PD15 设备树如下 注意需要内核勾选<> Polled GPIO Decoder Input driver
   rotary {
   compatible = “rotary-encoder”;
   pinctrl-names = “default”;
   /pinctrl-0 = <&rotary_pins>;/
   gpios = <&pio 3 14 GPIO_ACTIVE_LOW>, <&pio 3 15 GPIO_ACTIVE_LOW>; / PD14, PD15 /
   linux,axis = <0>; / REL_X */
   rotary-encoder,encoding = “gray”;
   rotary-encoder,relative-axis;
   };
   然后在内核勾选

4. 系统启动会有如下log

    [    0.111735] input: sunxi-keyboard as /devices/virtual/input/input0  这是板载的那个LRADC 按键
    [    1.668976] rotary-encoder soc@3000000:rotary: gray 这是旋转编码器
    [    1.675145] input: soc@3000000:rotary as /devices/platform/soc@3000000/soc@3000000:rotary/input/input1
    [    3.178668] input: soc@3000000:gpio_keys as /devices/platform/soc@3000000/soc@3000000:gpio_keys/input/input5 这是扩展出来的那4个按键
    
   

5. 查看系统里已注册的输入设备，用这个比较清楚，ls /dev/input也可以
   # evtest
   No device specified, trying to scan all of /dev/input/event*
   Available devices:
   /dev/input/event0: sunxi-keyboard
   /dev/input/event1: soc@3000000:rotary
   /dev/input/event2: sunxi-ir
   /dev/input/event3: audiocodec sunxi Audio Jack
   /dev/input/event4: soc@3000000:gpio_keys
   /dev/input/event5: ns2009_ts

6. 可以使用evtest或hexdump来测试按键是否正常了

7. 在代码使用就比较简单了
   #include <errno.h>
   #include <global.h>
   #include <linux/fcntl.h>
   #include <linux/input.h>
   #include <signal.h>
   #include <stdio.h> //-std=c99 -std=gnu99
   #include <stdlib.h>
   #include <string.h>
   #include <sys/types.h>
   #include <unistd.h>
   
   #define msleep(t) usleep((t)*1000)
   FILE *fp;
   int32_t fd_key;
   int32_t fd_encoder;
   struct input_event t;
   int main(int argc, char const *argv[])
   {
   
   fd_key = open(“/dev/input/event1”, O_RDONLY | O_NONBLOCK);
   if (fd_key < 0)
   {
   fprintf(stderr, “error:can not open /dev/input/event1\n”);
   return -1;
   }
   fd_encoder = open(“/dev/input/event4”, O_RDONLY | O_NONBLOCK);
   if (fd_encoder < 0)
   {
   fprintf(stderr, “error:can not open /dev/input/event4\n”);
   return -1;
   }
   
   while (1)
   {
   
   // rotary encoder
   if (read(fd_encoder, &t, sizeof(t)) == sizeof(t))
   {
   
   if (t.type == EV_REL)
   {
   LOG_D(“ROTARY DIR: %d->%s\n”, t.value, t.value == 1 ? “CC” : “CW”);
   rotary_encoder_handler(&u8g2, t.value);
   }
   }
   // key
   if (read(fd_key, &t, sizeof(t)) == sizeof(t))
   {
   if (t.type == EV_KEY)
   {
   switch (t.code)
   {
   case KEY_OK:
   LOG_D(“KEY_ENTER %s \n”, t.value ? “Pressed” : “Released”);
   if (t.value == 0)
   rotary_encoder_button_handler(&u8g2);
   break;
   case KEY_SELECT:
   LOG_D(“KEY_SELECT %s \n”, t.value ? “Pressed” : “Released”);
   break;
   case KEY_VOLUMEUP:
   LOG_D(“KEY_VOLUMEUP %s \n”, t.value ? “Pressed” : “Released”);
   if (t.value == 0)
   {
   rotary_encoder_handler(&u8g2, -1);
   }
   
   break;
   case KEY_VOLUMEDOWN:
   LOG_D(“KEY_VOLUMEDOWN %s \n”, t.value ? “Pressed” : “Released”);
   if (t.value == 0)
   {
   rotary_encoder_handler(&u8g2, 1);
   }
   break;
   default:
   break;
   }
   }
   }
   usleep(1);
   }
   
   return 0;
   }