Customize Infrared Receiver

Edge2 has reserved a IR connector. If you want to use an infrared remote (IR) control, you need to connect an IR receiver to Edge 2. The reference drawing is as follows:


Configuring IR control

This chapter mainly describes how to configure the IR control on Edge 2. The configuration steps can be divided into two parts:

  • Step 1: Modify the kernel driver by modifying the kernel space(Both Linux and Android need to modify this part).
  • Step 2: Modify key-value mapping by modifying the user space(Only Android needs to modify this part).

Modifying the kernel driver

In the Linux kernel, the IR driver only supports NEC encoding format. The following is how to configure IR control in the kernel.

Files involved in the kernel:


Defining the relevant data structure

Add the supported IR control key-value in the DTS file kernel/arch/arm64/boot/dts/rockchip/mixtile-edge2-evb.dtsi.

To configure the key-value relevant data structure:

&pwm7 {
        status = "okay";
        compatible = "rockchip,remotectl-pwm";
        remote_pwm_id = <3>;
        handle_cpu_id = <1>;
        remote_support_psci = <0>;
        pinctrl-names = "default";
        pinctrl-0 = <&pwm7_pins>;

        ir_key4 {
          rockchip,usercode = <0xbf00>;
          rockchip,key_table =
            <0xea    KEY_BACK>,
            <0xec    KEY_UP>,
            <0xeb    KEY_DOWN>,
            <0xee    KEY_LEFT>,
            <0xed    KEY_RIGHT>,
            <0xb7    KEY_VOLUMEUP>,
            <0xb6    KEY_VOLUMEDOWN>,
            <0xff    KEY_POWER>,
            <0xfe    KEY_MUTE>,
            <0xef    KEY_ENTER>,
            <0xe9    KEY_MENU>;

Note: The first column of rockchip,key_table is the key value, and the second column is the key code to be responded to.

Getting user code and IR key

Refer to driver: kernel/drivers/input/remotectl/rockchip_pwm_remotectl.c

Get the user code and key values from remotectl_do_something

                if ((RK_PWM_TIME_BIT1_MIN < ddata->period) &&
                    (ddata->period < RK_PWM_TIME_BIT1_MAX))
                        ddata->scandata |= (0x01 << ddata->count);
                if (ddata->count == 0x10) {
                        DBG_CODE("USERCODE=0x%x\n", ddata->scandata);
                        if (remotectl_keybd_num_lookup(ddata)) {
                                ddata->state = RMC_GETDATA;
                                ddata->scandata = 0;
                                ddata->count = 0;
                        } else {
                                if (rk_remote_print_code){
                                        ddata->state = RMC_GETDATA;
                                        ddata->scandata = 0;
                                        ddata->count = 0;
                                } else
                                        ddata->state = RMC_PRELOAD;

Note: The user can use the DBG_CODE() function to print the user code.

Edge 2 can make DBG_CODE printing by using the following command:

echo 1 > /sys/module/rockchip_pwm_remotectl/parameters/code_print

Compiling the IR driver into the kernel

Since the IR driver rockchip_pwm_remotectl.c already exists in the SDK, all we need to do is to compile the IR driver into the kernel. In the kernel source code, you can add the following two statements to the kernel/arch/arm64/configs/mixtile-edge2_defconfig file.


To compile the kernel (boot.img), refer to the Compile Kernel chapter for more details.

Android key-value mapping

This section is used to map the key value obtained in Linux to the corresponding key value on Android.

Files involved in the Android system:


The contents of the file are as follows:

key 28    ENTER
key 116   POWER
key 158   BACK
key 139   MENU
key 217   SEARCH
key 232   DPAD_CENTER
key 108   DPAD_DOWN
key 103   DPAD_UP
key 102   HOME
key 105   DPAD_LEFT
key 106   DPAD_RIGHT
key 115   VOLUME_UP
key 114   VOLUME_DOWN
key 113   VOLUME_MUTE

To compile Android, refer to the Compile kernel chapter for more details.

Burn boot.img and super.img with the burning tool to update. To burn the images, please refer to Update Firmware chapter for more details.