Timer and 12F509

Hello

I want to use the PIC 12F509 to monitoring one impuls in a Timewindow from 0 to 16 seconds, that means on power up a Timer starts and if i not receive one impuls until 16 seconds the programm stop, if the impuls come the Timer cleared to count again.

The 12F509 have no interrupt pin, than i must poll the pin, correct?
Have anyone make this with a 12F509? I have not programmimng anything with Timer, have anyone a sample code for the 12F509 with Timer

Thanks
Best Regards
Pedro

Hi,

How accurate do you need this 16 seconds to be and how long is is the signal you are looking for?

A simple way would be polling the pin in a tight loop with a short delay inside.

Lets say you have a delay of 10 ms in the loop and do this loop 1600 times you should end up with a 16 second time window.

If you need more accuracy yuu can adjust the delay by using delay_us if timing is critical..

You didnt mention the clock frequency but unless it is really slow it will be hard to get 16 seconds time by just using a timer... in that case you need to reset it several time or count how many times it overflows... or something

/me

Hello Jumper

I have two Jumpers that i read at power up to choose four possible timings
16 seconds, 18, 19 and 20 seconds
I want use on the PIC 12F509 the internal 4Mhz oscilator

Best Regards
Pedro

I might be slow.. but I still dont understand fully.


You have 2 jumpers you can read at startup to set the time window.. so you get 4 different times (16,18,19,29 sec).. I am with you this far.

Then you say you look for something to happen during this time window... if it happens.. then you start a new time window to look again... if it doesnt you stop the program.

so...

power up
check input pins
load a word variable with the correct time (1600 for 16 s and 2000 for 20 sec)

start_again:

n=0
for n =0 to word variable
check for your signal
if you find your signal goto start_again
Delay_ms(9)
Delay_us(1000) ' here you can adjust the loop time
next n

STOP


This could work unless you are looking for 16.000000000000000 seconds or similar. By adjusting the delay_us() time you can calibrate the loop time.

Since you doesnt seem to have anything else to do during this time why do you want to use the timer?
/me

Hi Jumper
You are right, i don't need to use the Timer

Thanks

Regards
Pedro