pic as a 555 alternative

jeffjohnvol

I want to use a 555 chip to give my stamp a point in which to measure elapsed time.· Rather than dealing with the 555, pots, resistors and caps, would a simple pic be an alternative?

I haven't used pic's before but I hear they are relatively inexpensive.· I prefer to keep my major work on a stamp, but this could provide a simpler solution than dealing with analog circuitry.

Has anyone done this?· What kind of investment would I have to make to even be able to program a pic?

Thanks.
Jeff

metron9

Sure it can be done. Check out the co-processor thread as it now has a seconds,minutes,hours and days timer.
The atmel tiny chips can be programmed with very inexpensive programmers and the software for both C and assembler are free as well.
There are complete programs that duplicate the time chips in the application notes at the atmel site. If you are going to choose between PIC and Atmel I think you will find Atmel hands down will be easier to use with more support at places like avrfreaks and http://www.mcselec.com/ where you can download Bascom for free.
links:

http://www.avrfreaks.net/ Here you will find all the tools you need and how they work.

http://www.atmel.com/dyn/products/app_notes.asp?family_id=607 The chip manufacture site.

Some of the chips like the tiny11 are only 35 cents. Their are dozens of chips to choose from. 8 pin dips to over 100 pin chips.

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LoopyByteloose

You might consider the fact that the BasicStamp1 and the BasicStamp2 both use a PIC.· You could use either one in lieu of a 'raw' PIC chip.

If you merely buy a Microchip PIC without the software support, you can only program in their free Assember.·

Also, you may or not need to add the oscillator circuit to have an accurate timekeeper.· Internal oscillators and RC timers can vary 7% due to temperature.· The only reason to use the internal oscillator is to allow you to have one DIP package to interface w/o outport timing support.

And finally, you can do all the same and more with the Parallax SX28 and have support here as it will provide you with education in SXB and SXassembler.

It seems to me that a BasicStamp1 would be a good fit and allow you to easily redeploy it if ever you need to redesign.

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Forrest

Why not use a time keeping chip like the DS1302 - it's easily interfaced to a BasicStamp, there are many examples available, very accurate and runs off a watch crystal.

jeffjohnvol

Kramer said...

You might consider the fact that the BasicStamp1 and the BasicStamp2 both use a PIC.· You could use either one in lieu of a 'raw' PIC chip.

If you merely buy a Microchip PIC without the software support, you can only program in their free Assember.·

Also, you may or not need to add the oscillator circuit to have an accurate timekeeper.· Internal oscillators and RC timers can vary 7% due to temperature.· The only reason to use the internal oscillator is to allow you to have one DIP package to interface w/o outport timing support.

And finally, you can do all the same and more with the Parallax SX28 and have support here as it will provide you with education in SXB and SXassembler.

It seems to me that a BasicStamp1 would be a good fit and allow you to easily redeploy it if ever you need to redesign.

Yes, for the one-off situation the BS1 would be easiest by far only running $30 and easier to program.

The SX chip would be a cheaper alternative if I had a bunch to do, or if I did this frequently, and I like sticking with one company.· I just didn't want to spend $50 when a $3 part would do.

Much ignorance on my part here, but I guess with a pic or an SX I would still need a crystal.

jeffjohnvol

Forrest said...
Why not use a time keeping chip like the DS1302 - it's easily interfaced to a BasicStamp, there are many examples available, very accurate and runs off a watch crystal.

For my situation I would just want a simple pulse that my stamp could measure over a 2 minute period.··High accuracy doesn't concern me.· ·I think with that chip I would need to dedicate several inputs for the serial, and I just want to use one input.

I would like to try that chip sometime though.· I think I still have the N&V article on it.