How to make a precision timer in STAMP?

lee_hanc · 2010-11-04 18:00

Hi,

I'm new in STAMP. I have a project that need a timer like a stopwatch and need to be precise as 0.1 ms. Like a timer, I set a time and then turn on. Whatever the program run, when the time is reaching the value that I set, I need to interrupt my program and know the time is out. Does anyone can help me for this? If I need another IC or stuff, what kind of stuff that I need to connect to STAMP? Thank u so much for the help

Mike Green · 2010-11-04 18:48

You are not going to be able to do this with a Stamp. There is no accessible timer inside with anything at all like the kind of accuracy you want and the instruction execution time for most Stamp instructions is on the order of the timing you need (100s of microseconds).

The Propeller could do this easily though, just not a Stamp. Even if you had an external timer with the sort of accuracy you want, the Stamp couldn't react to the end of the time interval fast enough to be useful for you.

What are you trying to do?

lee_hanc · 2010-11-04 23:17

Thanks for the reply...I try to build a "potentiostat" - for chemical sensor. It needs a voltage scan in a certain time. Actually I don't need that precise, I just wonder it will be best if I could have that precise. However, I wonder if I can have a timer like that, maybe no need that precise...does stamp able to do it?
for an example, I want to change my voltage (using DAC) every 10 ms without affected by the length of the programming code, just as below:

voltage_scan:

Timer = 1 ' starting the timer 10 ms

programming code ' there will be some code here
... ' which I don't need to know
... ' how long it will take,
... ' but surely less than 10ms

wait: ' wait for the timer to reach 10 ms
IF Timer =10ms THEN ' ex: if the code take 8ms, then
GOTO voltage_scan ' it just need to wait for 2 ms
ELSE
GOTO wait
ENDIF

does stamp able to do something like this? do you have any suggestion for my application like this? Btw, does propeller much more advanced than stamp could do? Thanks

Mike Green · 2010-11-05 07:31

It is possible to do what you want with a Stamp although the Stamp doesn't have a built-in timer. You have to write your program so that you know how long it takes to execute, then add delays to make up the difference.

The Propeller is much faster and has a very precise built-in clock that programs can use to create delays (resolution on the order of 10ns).

How to make a precision timer in STAMP?

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