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What is PWM Signal

Release date:2022-7-20 23:36:07

1. What is PWM signal

PWM (Pulse Width Modulation) is the abbreviation of Pulse Width Modulation. It modulates the width of a series of pulses to obtain the required waveform (including shape and amplitude), and digitally encodes the level of the analog signal, that is to say Adjust the change of signal, energy, etc. by adjusting the change of the duty cycle. The duty cycle refers to the percentage of the entire signal cycle when the signal is at a high level in a cycle. For example, the duty cycle of a square wave is 50%.

 pwm signal

2. How to realize PWM signal output

If you want to achieve PWM signal output how to output it?


1) The PWM signal can be output directly through the internal module of the chip. The premise is that this I/O port has an integrated module, which only needs a few simple steps. This kind of function module with PWM output is easier to program and design. The data is more precise. As shown in the figure below, the general IC port will indicate whether this is a PWM port;

2) But if there is no PWM function module inside the IC, or the requirements are not very high, you can use the I/O port to set some parameters to output the PWM signal, because the PWM signal is actually a combination of a series of high and low levels. The specific method is to add a timer to the I/O. The frequency of the PWM signal you require to output is consistent with your timer, and the timer interrupt is used to count, but this method is generally not used, unless the requirements for accuracy, frequency, etc. are not Very high can be achieved.

pwm module

HYXKIOT have some Bluetooth module support PWM function, as the Bluetooth Low Energy module HY-BT401, Bluetooth audio module HY-BT301C.


3. PWM signal application

The PWM signal converts the analog signal into the coding required by the digital circuit. Now, the digital circuit is basically used. Therefore, the PWM signal is used in many occasions. What we often see is the AC dimming circuit. The high level accounts for a little more, that is, the higher the duty cycle, the brighter the brightness, and the smaller the duty cycle, the less brightness. The premise is that the PWM frequency is greater than the recognition frequency of our human eyes, otherwise there will be flickering phenomenon.


In addition to dimming circuit applications, there are also applications in DC chopper circuits, buzzer drives, motor drives, inverter circuits, and humidifier atomization.

 pwm application

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