help with digital freqency and period meter.

[nkn]

please help for practical circuits for digital freqence and period meter.
not used mikroprocesor.

 

[blueroomelectronics]

What's wrong with using a microprocessor?

 

[crutschow]

You can do it without a microprocessor but it will require a lot more circuitry.

 

[unclejed613]

originally, a frequency counter consisted of a series of cascaded BCD counters and a timed gate. when the gate was high, the input signal caused the counters to count, when the gate momentarily went low (once per second, triggered by the transition), the count on the counters would be transferred to a display latch, and the counters would be reset for the next count. the gate goes high again, and the new count begins, while the latched data is displayed on a row of 7-segment LED digits. for best accuracy, the gate timing should be controlled from a very accurate timebase, usually a 10Mhz crystal divided down to 1hz by a series of cascaded decade counters. all this can be done with standard TTL or CMOS logic.

 

[crutschow]

originally, a frequency counter consisted of a series of cascaded BCD counters and a timed gate. when the gate was high, the input signal caused the counters to count, when the gate momentarily went low (once per second, triggered by the transition), the count on the counters would be transferred to a display latch, and the counters would be reset for the next count. the gate goes high again, and the new count begins, while the latched data is displayed on a row of 7-segment LED digits. for best accuracy, the gate timing should be controlled from a very accurate timebase, usually a 10Mhz crystal divided down to 1hz by a series of cascaded decade counters. all this can be done with standard TTL or CMOS logic.

But he also wants it to measure period. In that case he would use the input as a gate and count the clock.

 

[WTP Pepper]

Silabs 8051 CPU range have a beast of a PCA timer architecture built in. They can do gated counts (periods) and pulse counts (frequency) in a few lines of C.

I made a frequency counter many years ago using discrete TTL on veroboard. There were many chips and it drew about 1.5 amps. I could do the same with the above CPU and an LCD module in a few milliamps. Progress!