Neza-D1开发板学习之按键和旋转编码器篇

[xfdr0805]

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 = <KEY_VOLUMEUP>;
            gpios = <&pcf8574 0 GPIO_ACTIVE_LOW>; /* PP0 */
        };
   
        button@1 {
            label = "Key volume down";
            linux,code = <KEY_VOLUMEDOWN>;
            gpios = <&pcf8574 1 GPIO_ACTIVE_LOW>; /* PP1 */
        };
        
        button@2 {
            label = "Key back";
            linux,code = <KEY_BACK>;
            gpios = <&pcf8574 2 GPIO_ACTIVE_LOW>; /* PP2 */
        };
   
        button@3 {
            label = "Key enter";
            linux,code = <KEY_ENTER>;
            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;
    }
   

[tigger]

居然还有轮询的旋转编码器驱动，学到新姿势了。