High Accuracy Timer


Technical Support
Staff member
This is a high accuracy timer which uses a 20X2 to measure the time a gated clock pulse is present. Using 64MHz operating speed it has a timing period in excess of 18 hours, accurate to below 125ns.

The program includes auto-generation of a clock signal using PWMOUT ( up to 8MHz ) which can be gated to the clock input using just a push button. Possibly the most accurate push button timer so far :)



New Member
Could this be used as a stop watch

Hi Hippy

I am newish to this site and have enjoyed learning about pixace.

Your code looks very interesting although its very advanced for me.

I am trying to build a timer (stopwatch) to measure the speed of an object between two points. So would need to measure the time to 0.001 of a second i would think, unless your code goes better than that.

I hope to use to lasers as the switches to start and stop the timer. Setting the laser at a know distance would be vital, though i will practice with infrared to start with.

I am using serial4 x 20 LCD in my first project with work well

My code will then work out the speed in m/s or some other miles/hour etc

I think your code gives me the accurate clock (timer) that i would need.

I have tried your code through the simulate in editor but cant find out how to start and stop the timer.

Any advice would be welcome.


Technical Support
Staff member
There are a number of other projects which have dealt with measuring speed as an object passes between two points. A Forum Search will help there, with one thread I could find which will be useful being -


In my code you don't have to really worry about turning the timer on and off, it's more a counter of pulses which only occur when the clock signal is routed through to the timer acting as a counter. You'd use the two timing points to make the connection and then break it, the count during that time is then used to determine the speed.

I am not sure the code will simulate well as it relies on the physical hardware of the chip which the simulator cannot emulate.


Senior Member
This is a really great project an accurate timer for a 20x2 and just a few wires. The logic I generally understand but trying to convert this to an accurate stopwatch with start/lap/stop times display and failing to even set the program up so it runs and just update the timer when a pin goes high, if someone would be willing to help a novice in over his head it would be appreciated.