This guide will show you how to use PWM (Pulse Width Modulation).
Enable PWM
PWM_F:
1
2
3
4
| $ echo 1 | sudo tee /sys/class/pwm/pwmchip4/export
$ echo 1000000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/period
$ echo 500000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/duty_cycle
$ echo 1 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
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PWM_D:
1
2
3
4
| $ echo 1 | sudo tee /sys/class/pwm/pwmchip1/export
$ echo 1000000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/period
$ echo 500000 | sudo tee /sys/class/pwm/pwmchip1/pwm1/duty_cycle
$ echo 1 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable
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PWM_F:
1
2
3
4
| $ echo 1 | sudo tee /sys/class/pwm/pwmchip4/export
$ echo 1000000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/period
$ echo 500000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/duty_cycle
$ echo 1 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
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PWM_F:
1
2
3
4
| $ echo 1 | sudo tee /sys/class/pwm/pwmchip4/export
$ echo 1000000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/period
$ echo 500000 | sudo tee /sys/class/pwm/pwmchip4/pwm1/duty_cycle
$ echo 1 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
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Use an oscilloscope to check if the pins have been successfully enabled.
NoteIf you use an oscilloscope to view the PWM waveform, remember that the SBC and the oscilloscope need to share the same GND (ground).
Disable PWM
1
| $ echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
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1
| $ echo 0 | sudo tee /sys/class/pwm/pwmchip1/pwm1/enable
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1
| $ echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
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1
| $ echo 0 | sudo tee /sys/class/pwm/pwmchip4/pwm1/enable
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