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Pulse Width Modulation and Pulse Generation Module

Pulse width modulation (PWM) module generates a pulse train of fixed frequency.

The following terms are used to describe the PWM signal:

  • high time (T1) is a time period when the output equals to 1;

  • low time (T0) is a time period when the output equals to 0;

  • PWM period (T) is the sum of high time and low time:

  • duty cycle (D) is the ratio of the high time to the PWM period:

  • PWM frequency (f) is defined as 1/[PWM period]:

The following figure shows a PWM output waveform:

All the pins of USB-IO adapter GPIO-24 can be configured into PWM mode with high time (T1) and low time (T0) parameters in the range from 1 to 65535 ms (65.535 seconds). For more detailed information see Section 9.1, “Pulse Width Modulation (PWM) ”.

A.5 and B.5 pins can also generate high-frequency PWM (HPWM) with period (T) and high time (T1) parameters in the range from 1 to 340 µs. For more detailed information see Section 9.2, “High Frequency PWM (HPWM)”.

Sometimes it is more convenient to send single pulses on demand. Single pulses can be generated on any of the 24 pins. You can specify the length and logical level of the pulse. For more detailed information see Section 9.3, “Single Pulses”.