How do I determine Pulse Width Modulation (PWM) frequency resolution?

I want to know if the resolution of a DAQ for PWM is affected by both the bit width of the counter and the base frequency of the PC board.

Answer 1

[MathWorks Support Team]

The resolution depends on both the counter bit width and the counter base frequency.

 Resolution Frequency * 2^ B = Counter Base Frequency

where B is the number of bits.

For example, the Real Time Device (RTD) DM6804 uses an AMD9513 which has 16 bit counters and runs at a maximum frequency of 5 MHz. The full count is 2^16 = 65535 with maximum resolution when the full count is used. The resolution is 1/65535 = .0015%, and its associated frequency is 5 MHz / 65535 = 76.29 Hz.