RK3399实现uart、rs232、rs485以及接口光耦保护电路

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rk3399 串口不够用，参考设计中增加了wk2124这颗拓展芯片，可以转出4路串口，电路如下

dts配置只需要3步

1、关闭uart4

&uart4 {

    status = "disabled";

2、wk2124挂到spi1上面

&spi1 {

    status = "okay";

        spi_wk2xxx: spi_wk2xxx@00{

        status = "okay";

        compatible = "jinghong,spi-wk2xxx";

        reg = <0x00>;

        spi-max-frequency = <10000000>;

    // power-gpio = <&gpio2 4 GPIO_ACTIVE_HIGH>;

          //reset-gpio = <&gpio1 17 GPIO_ACTIVE_HIGH>;

      reset-gpio = <&gpio1 19 GPIO_ACTIVE_HIGH>;  

      irq-gpio = <&gpio1 2 IRQ_TYPE_EDGE_FALLING>;

      cs-gpio = <&gpio1 10 GPIO_ACTIVE_HIGH>;

        /* rk3399 driver support SPI_CPOL | SPI_CPHA | SPI_CS_HIGH */

        //spi-cpha;        /* SPI mode: CPHA=1 */

        //spi-cpol;      /* SPI mode: CPOL=1 */

        //spi-cs-high;

    };

3、检查gpio复用

max232电路

光耦隔离