Linux
如何正確配置 Beaglebone Black PWM
我試圖讓 PWM 工作但沒有任何成功。我將TI 處理器 SDK與am335x-boneblack.dts設備樹的修改版本一起使用（見下文）
PWM 驅動程序 (ehrpwm1) 正確探測並出現在
/sys/class/pwm/pwmchip0. 然後，我配置了晶片cd /sys/class/pwm/pwmchip0 echo 0 > export echo 1000000 > pwm0/period echo 250000 > pwm0/duty_cycle echo 1 > pwm0/enable但是，沒有 PWM 輸出。我錯過了一些明顯的東西嗎？
這是我製作的設備樹：
/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>; };
問題出在這個部分
&ehrpwm1 { pinctrl-name = "default"; pinctrl-0 = <&backlight_pin>; status = "okay"; };
pinctrl-name應該是pinctrl-names（注意末尾的“s”）