PWM Usage Tutorial#
What is PWM?#
PWM (Pulse Width Modulation) is a method of simulating analog signals by controlling the high/low level ratio (duty cycle) of a digital signal. It is commonly used for:
Controlling LED brightness
Driving motor speed
Adjusting audio volume
Generating tones/square wave signals
The K230 integrates two PWM hardware modules internally, each supporting 3 channels (6 channels in total):
Channels 0~2 share the same clock source (same frequency, with separate duty cycle settings)
Channels 3~5 use another independent clock source
Each channel can be configured to different output pins via
IOMUX
Example Overview#
The following example demonstrates how to use the K230’s PWM module to perform the following operations:
Initialize and start PWM output
Dynamically adjust frequency and duty cycle
Release PWM channel resources
Import Module and Initialize PWM#
from machine import PWM, Pin
# Initialize PWM channel 0, set frequency to 1kHz, duty cycle to 50%
pwm0 = PWM(Pin(42), freq=1000, duty=50)
PWM(channel number, frequency Hz, duty cycle %)Creates a PWM output for the specified channel, outputting a 1kHz square wave with a 50% duty cycle
Dynamically Adjust Frequency and Duty Cycle#
# Modify channel 0's output frequency to 2kHz
pwm0.freq(2000)
# Modify duty cycle to 10%
pwm0.duty(10)
freq(x): Set output frequency (unit: Hz)duty(x): Set duty cycle (unit: %, range 0~100)
Release Channel Resources#
# Completely release channel 0, turn off output and free underlying resources
pwm0.deinit()
deinit(): Close the channel, free resources, suitable for exit scenarios or switching functions
Example Output Waveform Description#
Assume we set channel 0 to output a 1kHz, 50% duty cycle PWM waveform. The waveform is:
Period T = 1ms
High level time = 0.5ms, Low level time = 0.5ms
|‾‾‾‾‾ ‾‾‾‾‾ ‾‾‾‾‾
| ‾‾‾‾‾ ‾‾‾‾‾
If the duty cycle is adjusted to 10%, the waveform is as follows:
|‾ ‾ ‾ ‾
|
PWM Channel Description#
Channel Number |
Module |
Clock Sharing Group |
|---|---|---|
0 |
PWM0 |
Group A |
1 |
PWM0 |
Group A |
2 |
PWM0 |
Group A |
3 |
PWM1 |
Group B |
4 |
PWM1 |
Group B |
5 |
PWM1 |
Group B |
⚠ Note: Channels in the same group share one frequency, but the duty cycle can be set independently
Application Scenarios#
LED Brightness Control (control brightness through duty cycle)
Buzzer Sound (control pitch through frequency)
Servo Control (specific duty cycle controls rotation angle)
DC Motor Speed Control (control average voltage through PWM)
Signal Waveform Generator (square wave, PWM modulated wave, etc.)