RK3568系列8——串口与PWM配置

发表于 更新于 分类于 ， Waline： 阅读次数： 本文字数： 2.2k 阅读时长 ≈ 5 分钟

　　串口和PWM已经在rk3568-evb.dtsi文件中有很多相关的示例，如果原理图中有用到相关的配置可以直接将对应的节点使能，这里再重新贴一下相关的DTS配置。

配置要点

  • 相关PIN脚是接在M1通道还是M2通道

DTS配置

  • PWM红外接收器：
    • remote_pwm_id: 未知
    • handle_cpu_id: 用来处理红外信号的CPU，4核CPU合法值为0~3
    • remote_support_psci：未知
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# 串口配置
&uart7 {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&uart7m2_xfer>;
};


# PWM配置
&pwm14 {
    status = "okay";
    pinctrl-names = "active";
    pinctrl-0 = <&pwm14m0_pins>;
};

# 如果使用到了PWM7，"rk3568-evb.dtsi"默认将其定义为了PWM红外接收器
# 需要将相关的配置删除，恢复成PWM功能
&pwm7 {
    status = "okay";
    compatible = "rockchip,rk3568-pwm", "rockchip,rk3328-pwm";
    pinctrl-names = "active";
    pinctrl-0 = <&pwm7_pins>;

    /delete-property/ remote_pwm_id;
    /delete-property/ handle_cpu_id;
    /delete-property/ remote_support_psci;
    /delete-node/ ir_key1;
    /delete-node/ ir_key2;
    /delete-node/ ir_key3;
};

# PWM红外接收器配置
&pwm3 {
    status = "okay";

    compatible = "rockchip,remotectl-pwm";
    remote_pwm_id = <3>;
    handle_cpu_id = <1>;
    remote_support_psci = <0>;
    pinctrl-names = "default";
    pinctrl-0 = <&pwm3_pins>;

    ir_key1 {
        rockchip,usercode = <0x00ff>;
        rockchip,key_table =
            <0xea KEY_VOLUMEUP>,
            <0xe3 KEY_VOLUMEDOWN>;
    };
    ir_key2 {
        ........
    };
};

PWM调试

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# 查看PWM汇总信息
cat /sys/kernel/debug/pwm
> platform/fe700030.pwm, 1 PWM device
>  pwm-0   (red                 ): requested period: 25000 ns duty: 0 ns polarity: normal
> 
> platform/fe700020.pwm, 1 PWM device
>  pwm-0   (blue                ): requested period: 25000 ns duty: 0 ns polarity: normal
> 
> platform/fe6e0030.pwm, 1 PWM device
>  pwm-0   (green               ): requested period: 25000 ns duty: 0 ns polarity: normal
>
> platform/fe6e0020.pwm, 1 PWM device
>  pwm-0   (all                 ): requested period: 25000 ns duty: 0 ns polarity: inverse
> 
> platform/fe6e0010.pwm, 1 PWM device
>  pwm-0   (backlight           ): requested enabled period: 25000 ns duty: 11750 ns polarity: normal

# 调试PWM，前提是该PWM不能被占用
cd /sys/class/pwm/pwmchip3/
echo 0 > export # 一个PWM芯片可以控制多个PWM节点，RK3568只有1个
cd pwm0/
echo normal > polarity  # 设置极性 normal | inverse
echo 25000 > period     # 设置工作周期(ns)
echo 12500 > duty_cycle # 设置占空比(ns)
echo 1 > enable         # 使能pwm节点