Question

我很难在Beaglebone Black上进行第二次芯片选择。

我使用/ lib / firmware中的.dts和我的发行版（Angstrom，内核3.8.13）：

/*
 * Copyright (C) 2013 CircuitCo
 *
 * Virtual cape for SPI1 on connector pins P9.29 P9.31 P9.30 P9.28
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
/dts-v1/;
/plugin/;

/ {
    compatible = "ti,beaglebone", "ti,beaglebone-black";

    /* identification */
    part-number = "BB-SPI1-01";
    version = "00A0";

    /* state the resources this cape uses */
    exclusive-use =
        /* the pin header uses */
        "P9.31",    /* spi1_sclk */
        "P9.29",    /* spi1_d0 */
        "P9.30",    /* spi1_d1 */
        "P9.28",    /* spi1_cs0 */
            "P9.42",    /* spi1_cs1 */
        /* the hardware ip uses */
        "spi1";

    fragment@0 {
        target = <&am33xx_pinmux>;
        __overlay__ {
            /* default state has all gpios released and mode set to uart1 */
            bb_spi1_pins: pinmux_bb_spi1_pins {
                pinctrl-single,pins = <
                    0x190 0x13  /* mcasp0_aclkx.spi1_sclk,  OUTPUT_PULLUP | MODE3 */
                    0x194 0x33  /* mcasp0_fsx.spi1_d0,      INPUT_PULLUP | MODE3 */
                    0x198 0x13  /* mcasp0_axr0.spi1_d1,     OUTPUT_PULLUP | MODE3 */
                    0x19c 0x13  /* mcasp0_ahclkr.spi1_cs0,      OUTPUT_PULLUP | MODE3 */
                    0x164 0x12  /* eCAP0_in_PWM0_out.spi1_cs1   OUTPUT_PULLUP | MODE2 */
                >;
            };
        };
    };

    fragment@1 {
        target = <&spi1>;   /* spi1 is numbered correctly */
        __overlay__ {
            status = "okay";
            pinctrl-names = "default";
            pinctrl-0 = <&bb_spi1_pins>;

            #address-cells = <1>;
            #size-cells = <0>;

                    cs-gpios         = <&gpio4 17 0>, <&gpio1 7 0>;
            spi1_0{
                #address-cells = <1>;
                #size-cells = <0>;

                compatible = "spidev";

                reg = <0>;
                spi-max-frequency = <16000000>;
            };


            spi1_1{
                #address-cells = <1>;
                #size-cells = <0>;

                compatible = "spidev";

                reg = <1>;
                spi-max-frequency = <16000000>;
            };
        };
    };
};

我用dtc编译它并用uEnv.txt激活它：

capemgr.enable_partno=BB-SPI1-01

（HDMI和HDMIN海角都被禁用）

我有/ dev /：

中显示的两个SPI设备

/dev/spidev2.0  /dev/spidev2.1

并且spi接口使用引脚，如下所示：

    root@beaglebone:~# cat $PINS | grep spi1
pin 89 (44e10964): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
pin 100 (44e10990): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
pin 101 (44e10994): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
pin 102 (44e10998): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
pin 103 (44e1099c): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins

模式很好：

pin 89 (44e10964) 00000012 pinctrl-single
pin 100 (44e10990) 00000013 pinctrl-single 
pin 101 (44e10994) 00000033 pinctrl-single 
pin 102 (44e10998) 00000013 pinctrl-single 
pin 103 (44e1099c) 00000013 pinctrl-single

我在C中成功使用了一个使用第一个spidev（spidev2.0）和第一个芯片选择的程序，但是当我使用spidev2.1时，引脚42上没有任何东西（MOSI，MISO和CLK正在工作）

有什么想法吗？

提前致谢

Answer 1

我自己找到了答案：

引脚42是特殊的，因为它连接到两个I / O.因此，为了使用其中一个I / O，您必须将另一个作为输入。

来源：Beaglebone黑色系统参考手册http://www.digikey.com/web%20export/supplier%20content/ti_296/mkt/boards/BBB_SRM.pdf?redirected=1第71页。

但是现在我还有一个非常奇怪的问题......我在这里发布了它：Trouble with SPIDEV, device tree and .dtbo name with Beaglebone Black

BBB - 无法通过设备树获得第二个SPI芯片选择

1 个答案: