Time signal

[KeithSloan]

What is the best way of going about trying to decode a time signal. i.e. Ones and Zero's on a signal line?

Can anybody point me at some examples?

Thanks Keith

[Benj]

Hello

The easiest way is to wait until the signal changes.

Eg

While (porta.0 == 0); //Wait for RA0 to go high
While (porta.0 == 1); //Wait for RA0 to go low

once you know that pin RA0 has just changed from high to low you can begin counting. The easiest way to do this is to use a hardware timer. Either Timer0 for a small period or Timer1 for a larger period.

tmr0 = 0;
tmr1 = 0;

Then all you have to do is wait until the state changes again and retreive the timer value.

While (porta.0 == 0); //Wait for RA0 to go high
count = tmr1;

For further help on using the timers and configuring their counting rate see the specific PICmicro datasheet for your target processor.

[Benj]

I also have a sample frequency counter program using flowcode V3 if you require it.

[goldwingers]

Benj. I could do with a copy of your frequency meter file. I have been trying to build a complex program to measure engine speed and other stuff. would be most grateful
Ian

[Benj]

The code for the frequecy meter is available from here.

http://www.matrixmultimedia.com/softwar ... ounter.fcf

The code is designed to print out the freqency of pulses incoming to the pin specified in the Read_Input macro.

Max Input freq approx 32000Hz

Higher frequencies ( < 64000Hz ) can be measured by modifying the LCD Print Number Function

Let me know if you have any problems