无法在BeagleBone Green Wireless上配置SPI0 [英] Cannot configure SPI0 on BeagleBone Green Wireless

问题描述

注意:所选答案是解决问题的原始答案，有关更多详细信息，请参见下面的其他答案.

我无法在BeagleBone Green Wireless(BBGW)上配置SPI0.我正在尝试不使用覆盖而仅使用纯DeviceTree来实现这一目标.

I'm not able to configure SPI0 on my BeagleBone Green Wireless (BBGW). I'm trying to achieve this without using overlays, only pure DeviceTree.

/dev/spidev1.0和/dev/spidev1.1在那里，但是任何I/O都会返回垃圾.

/dev/spidev1.0 and /dev/spidev1.1 are there, but any I/O returns garbage.

连接到SCLK的示波器大部分显示噪声，这是图片(每张图片的时间范围不同).

Oscilloscope connected to SCLK displays mostly noise, here are pictures (each in different time scale).

.dts/.dtsi的重要部分:

Important parts of my .dts/.dtsi:

&am33xx_pinmux {
    bb_spi0_pins: pinmux_bb_spi0_pins {
        pinctrl-single,pins = <
            BONE_P9_22 ( PIN_INPUT_PULLUP | MUX_MODE0 ) // SCLK
            BONE_P9_21 ( PIN_INPUT_PULLUP | MUX_MODE0 ) // MISO
            BONE_P9_18 ( PIN_OUTPUT_PULLUP | MUX_MODE0 ) // MOSI
            BONE_P9_17 ( PIN_OUTPUT_PULLUP | MUX_MODE0 ) // CS0
        >;
    };
};

&spi0 {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&bb_spi0_pins>;
    #address-cells = <1>;
    #size-cells = <0>;

    channel@0 {
        #address-cells = <1>;
        #size-cells = <0>;
        compatible = "linux,spidev";
        spi-max-frequency = <16000000>;
        reg = <0>;
    };

    channel@1 {
        #address-cells = <1>;
        #size-cells = <0>;
        compatible = "linux,spidev";
        spi-max-frequency = <16000000>;
        reg = <1>;
    };
};

---

更多信息:

---

More info:

• 我没有使用可用的am335x-bone-pinmux-spi0.dtsi，因为它启用了时钟相移(spi-cpha)
• 我打算使用SPI与DWM1000通讯
• 我正在使用带有上述DWM1000，一个电源转换器和2个电机驱动器的自定义斗篷，它们连接到P8连接器上的PRU引脚
• 完整的覆盖文件: https://github.com/GroupOfRobots/RobotConfig/tree/v3/DevTree
• uEnv.txt: https://github.com/GroupOfRobots/RobotConfig/blob/v3/uEnv.txt
• 系统:Debian 9.0 (testing)
• 内核:4.4.80-ti-rt-r116(我也尝试过使用不同的内核，但是我需要ti-rt分支之一)

• I didn't use the available am335x-bone-pinmux-spi0.dtsi as it enables the clock phase shift (spi-cpha)
• I'm intending to use the SPI to communicate with a DWM1000
• I'm using a custom cape with the said DWM1000, a power converter and 2 motor drivers connected to PRU pins on P8 connector
• Full overlay files: https://github.com/GroupOfRobots/RobotConfig/tree/v3/DevTree
• uEnv.txt: https://github.com/GroupOfRobots/RobotConfig/blob/v3/uEnv.txt
• system: Debian 9.0 (testing)
• kernel: 4.4.80-ti-rt-r116 (I've tried on different ones too, but I need one of the ti-rt branch)

PS.我知道它是BBGW而不是BBB，但是BBG/BBGW还没有标签.

PS. I know it's BBGW not BBB but there are no tags for BBG/BBGW (yet).

更新:

该行为已在其他内核上被验证为相同，即:

The behaviour was verified to be the same on other kernels, namely:

• 4.4.85-armv7-x14
• 4.4.84-ti-r120
• 4.4.85-bone19

另外，我还用跳线将MISO和MOSI(P9上的引脚18和21)连接在一起，然后运行了spidev_test，结果如下:

Additionally I've connected together MISO and MOSI (pins 18 and 21 on P9) with a jumper wire and ran spidev_test, here are the results:

$ sudo ./spidev_test -v -p "abcdefghijklmnopqrstuvwxyz1234\xde\xad" 
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 KHz)
TX | 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70 71 72 73 74 75 76 77 78 79 7A 31 32 33 34 DE AD  | abcdefghijklmnopqrstuvwxyz1234ޭ
RX | 03 0C 0F 30 33 3C 3F C0 C3 CC CF F0 F3 FC FF 00 03 0C 0F 30 33 3C 3F C0 C3 CC 03 0C 0F 30 FC F3  | ...03<?�������.....03<?���...0��

我无法用它做任何事，但是我几乎可以确定这不是由于时钟线上的电容器所致，该电容器在本次测试中未使用.

I can't make anything out of it, but it makes me almost sure it's not due to the capacitors on clock line, which is unused in this test.

推荐答案

我遇到了同样的问题，我使用的是adafruit-spi0叠加层，但无法正常工作.我能够在从属spi设备上发送数据，并且接收到的数据还可以，但是当第二个设备将数据发送回BBGW时，我没有收到我发送的值.

I had the same problem, i was using adafruit-spi0 overlays and i couldn't get it working. I was able to send the data on a slave spi device and the recieved data was ok, but when the second device sends the data back to my BBGW i was not getting the values that i have sent.

这就是我解决的方法，spi0 clk上有两个电容器100pf，它们会引起反射，从而导致双时钟数据，您需要将其删除.

This is how i solved this, there are two capacitors 100pf on the spi0 clk they are causing reflections resulting in double-clocked data, you need to remove them.

我的董事会是从一家老牌工作室订购的.

My board was oredered from seeed studio.

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