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    T113s spi0 cs0 的疑难问题

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    • O
      Ou13556101201 LV 2 last edited by

      spi发送数据,两个字节之间的cs是长期低电平. 标准的spi不是两个字节之间cs会拉高一下再拉低吗? cs是可控的,比如发送10个字节,会拉低10个字节的长度.但每个字节之间没有拉高, clk也没有空隙. 感觉就是10个字节连发一样.
      我的配置如下:
      &spi0 {
      clock-frequency = <100000000>;
      pinctrl-0 = <&spi0_pins_a &spi0_pins_b>;
      pinctrl-1 = <&spi0_pins_c>;
      pinctrl-names = "default", "sleep";
      /spi-supply = <&reg_dcdc1>;/
      spi_slave_mode = <0>;
      spi0_cs_number = <1>;
      spi0_cs_bitmap = <1>;
      sample_mode =<1>;
      sample_delay = <10>;
      spi0_cs_bitmap = <1>;
      spi_dbi_enable = <0>;
      status = "okay";

      spi_board1@0 {
      	device_type = "spi_board1";
      	compatible = "spidev";
      	spi-max-frequency = <100000000>;
      	reg = <0x0>;
      	spi-rx-bus-width = <0x1>;
      	spi-tx-bus-width = <0x1>;
      	status = "okay";
      };
      

      示波器如下图
      df1e2f17-41ff-434c-bd39-c8b218c3a481-084b2f968f5a3081544cb8260cf5772.jpg

      黄线是clk,蓝线是cs. cs一直拉低知道数据结束. 字节间没有拉高 用的是spi_test测试的.
      求解 谢谢

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      • J
        Jingyan LV 5 @Ou13556101201 last edited by Jingyan

        @ou13556101201 不是很清楚你想要达到怎样的效果。
        SPI协议规定一次传输中,CS是持续有效(你所说的拉低)。如果一次传输是4字节,那么就是CS包住连续的32个CLK;如果一次传输是1字节,那么就是CS包住8个CLK。
        c9f869fa-7b8f-4855-bbb9-345e8dbd1e92-image.png

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