我尝试过让 PWM 工作但没有成功。我正在使用TI 处理器 SDK与修改版本am335x-boneblack.dts设备树（见下文）
PWM 驱动程序 (erpwm1) 正确探测并出现在 中/sys/class/pwm/pwmchip0。然后，我配置了芯片
cd /sys/class/pwm/pwmchip0
echo 0 > export
echo 1000000 > pwm0/period
echo 250000 > pwm0/duty_cycle
echo 1 > pwm0/enable
但没有 PWM 输出。我错过了一些明显的东西吗？
这是我制作的设备树：
/dts-v1/;
#include "am33xx.dtsi"
#include "am335x-bone-common.dtsi"
/ {
model = "TI AM335x BeagleBone Black";
compatible = "ti,am335x-bone-black", "ti,am335x-bone", "ti,am33xx";
};
&ldo3_reg {
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-always-on;
};
&mmc1 {
vmmc-supply = <&vmmcsd_fixed>;
};
&mmc2 {
vmmc-supply = <&vmmcsd_fixed>;
pinctrl-names = "default";
pinctrl-0 = <&emmc_pins>;
bus-width = <8>;
status = "okay";
};
&am33xx_pinmux {
lcd_pins: lcd_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x8a0, PIN_OUTPUT | MUX_MODE0) /* P9.45, lcd_data0 */
AM33XX_IOPAD(0x8a4, PIN_OUTPUT | MUX_MODE0) /* P9.46, lcd_data1 */
AM33XX_IOPAD(0x8a8, PIN_OUTPUT | MUX_MODE0) /* P9.43, lcd_data2 */
AM33XX_IOPAD(0x8ac, PIN_OUTPUT | MUX_MODE0) /* P9.44, lcd_data3 */
AM33XX_IOPAD(0x8b0, PIN_OUTPUT | MUX_MODE0) /* P9.41, lcd_data4 */
AM33XX_IOPAD(0x8b4, PIN_OUTPUT | MUX_MODE0) /* P9.42, lcd_data5 */
AM33XX_IOPAD(0x8b8, PIN_OUTPUT | MUX_MODE0) /* P9.39, lcd_data6 */
AM33XX_IOPAD(0x8bc, PIN_OUTPUT | MUX_MODE0) /* P9.40, lcd_data7 */
AM33XX_IOPAD(0x8c0, PIN_OUTPUT | MUX_MODE0) /* P9.37, lcd_data8 */
AM33XX_IOPAD(0x8c4, PIN_OUTPUT | MUX_MODE0) /* P9.38, lcd_data9 */
AM33XX_IOPAD(0x8c8, PIN_OUTPUT | MUX_MODE0) /* P9.36, lcd_data10 */
AM33XX_IOPAD(0x8cc, PIN_OUTPUT | MUX_MODE0) /* P9.34, lcd_data11 */
AM33XX_IOPAD(0x8d0, PIN_OUTPUT | MUX_MODE0) /* P9.35, lcd_data12 */
AM33XX_IOPAD(0x8d4, PIN_OUTPUT | MUX_MODE0) /* P9.33, lcd_data13 */
AM33XX_IOPAD(0x8d8, PIN_OUTPUT | MUX_MODE0) /* P9.31, lcd_data14 */
AM33XX_IOPAD(0x8dc, PIN_OUTPUT | MUX_MODE0) /* P9.32, lcd_data15 */
AM33XX_IOPAD(0x820, PIN_OUTPUT | MUX_MODE1) /* P9.19, lcd_data23 */
AM33XX_IOPAD(0x824, PIN_OUTPUT | MUX_MODE1) /* P9.13, lcd_data22 */
AM33XX_IOPAD(0x828, PIN_OUTPUT | MUX_MODE1) /* P9.14, lcd_data21 */
AM33XX_IOPAD(0x82c, PIN_OUTPUT | MUX_MODE1) /* P9.17, lcd_data20 */
AM33XX_IOPAD(0x830, PIN_OUTPUT | MUX_MODE1) /* P9.12, lcd_data19 */
AM33XX_IOPAD(0x834, PIN_OUTPUT | MUX_MODE1) /* P9.11, lcd_data18 */
AM33XX_IOPAD(0x838, PIN_OUTPUT | MUX_MODE1) /* P9.16, lcd_data17 */
AM33XX_IOPAD(0x83c, PIN_OUTPUT | MUX_MODE1) /* P9.15, lcd_data16 */
AM33XX_IOPAD(0x8e0, PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* P9.27, lcd_vsync */
AM33XX_IOPAD(0x8e4, PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* P9.29, lcd_hsync */
AM33XX_IOPAD(0x8e8, PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* P9.28, lcd_pclk */
AM33XX_IOPAD(0x8ec, PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* P9.30, lcd_ac_bias_en */
/* LCD enable */
AM33XX_IOPAD(0x88c, PIN_OUTPUT_PULLUP | MUX_MODE7) /* P8.19, gpio2[1] */
>;
};
backlight_pin: backlight_pin {
pinctrl-single,pins = < AM33XX_IOPAD(0x848, PIN_OUTPUT | MUX_MODE6) >; /* P9.14, gpio1[18] */
};
touchscreen_pins: touchscreen_pins {
pinctrl-single,pins = < AM33XX_IOPAD(0x9a4, PIN_INPUT_PULLUP | MUX_MODE7) >; /* P9.27, gpio3[19] */
};
dcan0_pins: dcan0_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x97c, PIN_INPUT_PULLUP | MUX_MODE2) /* P9.19, ddcan0_rx */
AM33XX_IOPAD(0x978, PIN_OUTPUT_PULLUP | MUX_MODE2) /* P9.20, ddcan0_tx */
>;
};
uart1_pins: uart1_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x980, PIN_INPUT_PULLUP | MUX_MODE0) /* P9.26, uart1_rxd */
AM33XX_IOPAD(0x984, PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* P9.24, uart1_txd */
>;
};
uart2_pins: uart2_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x950, PIN_INPUT_PULLUP | MUX_MODE1) /* P9.22, uart2_rxd */
AM33XX_IOPAD(0x954, PIN_OUTPUT_PULLDOWN | MUX_MODE1) /* P9.21, uart2_txd */
>;
};
uart4_pins: uart4_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x870, PIN_INPUT_PULLUP | MUX_MODE6) /* P9.11, uart4_rxd */
AM33XX_IOPAD(0x874, PIN_OUTPUT_PULLDOWN | MUX_MODE6) /* P9.13, uart4_txd */
>;
};
uart5_pins: uart5_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x8c4, PIN_INPUT_PULLUP | MUX_MODE4) /* P8.38, uart5_rxd */
AM33XX_IOPAD(0x8c0, PIN_OUTPUT_PULLDOWN | MUX_MODE4) /* P8.37, uart5_txd */
>;
};
ehrpwm1_pins: ehrpwm1_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x848, PIN_OUTPUT | MUX_MODE6) /* P9.14, EHRPWM1A */
AM33XX_IOPAD(0x84c, PIN_OUTPUT | MUX_MODE6) /* P9.16, EHRPWM1B */
>;
};
};
&epwmss1 {
status = "okay";
};
&ehrpwm1 {
pinctrl-name = "default";
pinctrl-0 = <&backlight_pin>;
status = "okay";
};
&lcdc {
status = "okay";
blue-and-red-wiring = "crossed";
};
&sgx {
status = "okay";
};
/ {
lcd0: display {
status = "okay";
compatible = "ti,tilcdc,panel";
label = "lcd";
pinctrl-names = "default";
pinctrl-0 = <&lcd_pins>;
enable-gpios = <&gpio2 1 GPIO_ACTIVE_HIGH>; /* P8.19 */
panel-info {
ac-bias = <255>;
ac-bias-intrpt = <0>;
dma-burst-sz = <16>;
bpp = <32>;
fdd = <0x80>;
sync-edge = <0>;
sync-ctrl = <0>;
raster-order = <0>;
fifo-th = <0>;
};
display-timings {
native-mode = <&timing0>;
timing0: 800x480 {
clock-frequency = <45000000>;
hactive = <800>;
vactive = <480>;
hfront-porch = <40>;
hback-porch = <40>;
hsync-len = <48>;
vback-porch = <29>;
vfront-porch = <13>;
vsync-len = <3>;
hsync-active = <0>;
vsync-active = <0>;
};
};
};
};
&i2c2 {
polytouch: edt-ft5x06@38 {
compatible = "edt,edt-ft5406", "edt,edt-ft5x06";
reg = <0x38>;
pinctrl-names = "default";
pinctrl-0 = <&touchscreen_pins>;
interrupt-parent = <&gpio3>;
interrupts = <19 0>; /* P9.27 */
touchscreen-size-x = <799>;
touchscreen-size-y = <479>;
xfuzz = <0>;
yfuzz = <0>;
};
};
&rtc {
system-power-controller;
};
&dcan0 {
status = "okay";
pinctrl-name = "default";
pinctrl-0 = <&dcan0_pins>;
};
&uart1 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&uart1_pins>;
};
&uart2 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&uart2_pins>;
};
&uart4 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&uart4_pins>;
};
答案1
问题出在这一部分
&ehrpwm1 {
pinctrl-name = "default";
pinctrl-0 = <&backlight_pin>;
status = "okay";
};
pinctrl-name应该是pinctrl-names（注意末尾的“s”）