Interrupt & device setup for a PIC16F628A in Microcode Studio Plus

[wildpikachu]

Hi Alain.
thanks for the reply, really cleared things up for me. I wasnt going to use timer1 to generate an interrupt but have decided to let it now. I'm using a simple repeated check on RB0 to check for a change instead of using an interrupt.

I've attached my code, seems right to me but if anyone finds any problems or has any advice please let me know.

Cheers
Guy

[Acetronics2]

Hi, Picatchu

nice code template ... easy to read !

some tricks :

  if (PORTB.0 = rb0old) then goto changetest ' If there is no change then test again

change for :

While (PORTB.0 = rb0old)
Wend

this will loop till a change occurs ... ( much faster ! )

Note here I did not understand why use the "change" feature : from your explanations ... if "back" signal detected, it simply turns PortB.0 input ON ( ... or OFF depending Hardware)

    dummy = (time((6 * temp)+ 3300))    ' calculate part of the full calculation

to me ( I can fail ...)
it might be :

    dummy = (time*((6 * temp)+ 3300))    ' calculate part of the full calculation

By the Way : Speed of sound in air = SQR ( 13 * 287* (273.15 + Temp) /10 )

... @ sea level ...

...

Alain

PS: May be you could try a "samples" request here ...

http://www.midascomponents.co.uk/

[wildpikachu]

Hi alain.

thanks for the "while" and maths suggestions and for the complement on my code, I will implement them. the checking for a change on RB0 is because the receiving circuit is set to be extremely sensitive and I am not sure what state the comparator, that is connected to RB0, will be in (either 0V or 5V) thats why i'm checking for a change so that regardless of what state the comparator is initially i will stop timer1 as soon as possible. if the code was this: if PORTB.0 = 1 and initially the comparator was at a high i would get an instant stop without even receiving a signal. well in my mind it makes sence :-)

The calculation is got from one of my physics books and modified it to get rid of any decimal places and to work the distance out in one. it uses temperature in celcius rather than Kelvin.

thanks for the link, lets see if they are willing to send overseas :-)

Cheers and thanks again for the help!

- Guy