• sales

    +86-0755-88291180

Luckfox Pico RV1103【Tutorial on how to use PWM】

Due to pin multiplexing on the LuckFox Pico and LuckFox Pico Plus, there may be conflicts in pin functionality, so PWM functionality cannot be enabled by default for all pins.


】Use the GPIO sysfs interface to control PWM:


1] View the default enabled PWM interfaces:

# ls -l /sys/class/pwm

lrwxrwxrwx    1 root     root             0 pwmchip10 -> ../../devices/platform/ff490020.pwm/pwm/pwmchip10

lrwxrwxrwx    1 root     root             0 pwmchip1 -> ../../devices/platform/ff350010.pwm/pwm/pwmchip1

lrwxrwxrwx    1 root     root             0 pwmchip11 -> ../../devices/platform/ff490030.pwm/pwm/pwmchip11

lrwxrwxrwx    1 root     root             0 pwmchip0 -> ../../devices/platform/ff350000.pwm/pwm/pwmchip0


2] Test PWM. Export PWM1_M0 (GPIO0_A4_d) to the user space:

echo 0 > /sys/class/pwm/pwmchip1/export


3] Set the PWM period unit to ns. For example, the period of a 1KHz frequency is 1000000ns:

echo 1000000 > /sys/class/pwm/pwmchip1/pwm0/period


4] Set the duty cycle:

 #Set the duty cycle to 10% (with a period of 100,000 nanoseconds and a duration of 10,000 nanoseconds).

echo 100000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle  

echo 200000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 300000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 400000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 500000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 600000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 700000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 800000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 900000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

 # Set the duty cycle to 100% (with a period of 1,000,000 nanoseconds and a duration of 1,000,000 nanoseconds).

echo 1000000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

#Set the duty cycle to 0, which is equivalent to stopping the duty cycle output.

echo 0 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle


5]  Set the normal PWM polarity:

#Set the normal PWM polarity:

echo "normal" > /sys/class/pwm/pwmchip1/pwm0/polarity

#Set the inverted PWM polarity:

echo "inversed" > /sys/class/pwm/pwmchip1/pwm0/polarity


6] Enable PWM :

echo 1 > /sys/class/pwm/pwmchip1/pwm0/enable




7] Disable PWM :

echo 0 > /sys/class/pwm/pwmchip1/pwm0/enable



8] Disable exporting PWM to user space:

echo 0 > /sys/class/pwm/pwmchip1/unexport


9] Screenshot of the operation process:



】Test the built-in sample program of the official SDK:


(The following operations need to be performed in the terminal of the Pico development board)

3] Run the test sample program: 
chmod 777 ./luckfox_pwm_test
## Grant executable permissions to the file
./luckfox_pwm_test 3


4] Running result:

TAG: Core3566104000 Raspberry Pi Pico 2 RP2350B RP2350-PiZero Development Board PSRAM DVI For HDMI Raspberry Pi 5 DSI display ESP32 ST7789 tutorial UART To Ethernet Milk-V Duo RJ45 Tutorial Raspberry Pi Mini TV MiniPCIe Interface 2 CH CAN Card USB CAN Multiple Protection Circuits For Linux/Windows Raspberry Pi Display Driver Board Raspberry-Pi-1.54inch-LCD-Display-Touchscreen-configuration-Bookworm-Lite For Pi5 Raspberry Pi CM5 IO BASE A Mini Board a Base Development Platform Compute Module 5 IO Board MPS2280D Raspberry Pi 5 PCIe to M.2 NVMe Dual SSD Adapter Board HAT Pi5 Double 2280 ESP32 S3 LCD Development Board 1.3 inch Display 1.3inch Screen ST7789 240x240 Mini TV SD-Port QST QMI8658 Gyro Sensor LVGL For Arduino Raspberry Pi 5 Speaker CV1800B Raspberry Pi 1.28inch Round LCD RP2040 LoRa Spotpear Industrial USB to RS485 Converter