Period measurement

1. Nov 30, 2005

formulajoe

I was designing a circuit to determine frequency of signals using a counter as the main part of the circuit. However, I was just informed that period must also be measured or have the circuit perform one of the other.
Are there ICs that are able to determine the period between rising edges? If so, I will be able to use transistors to multiplex between frequency or period measurement.
The microcontroller I will be using is the motorola HS12. I know there are some ports on the HS12 that can be used for input-capture. The period could easily be found using these ports. Can these ports also be configured for pulse accumulation?

2. Nov 30, 2005

Staff: Mentor

If you want to turn a frequency meter into a period measuring device, just put a known clock into the input of the frequency meter, and trigger the meter with your signal that you want the period of. Put in 1MHz into the frequency counter's input if you want the period readout in microseconds.

I'm not familiar with the HS12 uC, but if it has on-chip timer counter blocks, then yes, that would be a good way to capture the period data for your waveform, and then you can calculate the frequency from that. With a small uC, you may want to use a look-up table to do the inverse function from period to frequency.