Some pins constantly high!

kutalinelucas

Hey guys, I was wondering if i could get some advice...

This is my first delve into the world of bs, and i'm trying to get a stepper running. I've done this with some success but now it seems two of the 4 pins I am using remain high at 5v, even though they are programmed to toggle as the other 2 do, and it did this until 20 minutes ago

I've isolated the chip, supply it with a regulated 9v and I still have the problem. Does this mean the chip, or those pins are buggered? or is there something else I could try...?

Cheers

kutalinelucas

Any ideas guys? Its now happened to two bs2 chips, or 50 quids worth of kit...
I've tried re-programing but to no avail...

Mike Green

It is possible that you've damaged the chip. It's impossible to tell without a schematic of your setup and a copy of your source program. Any time you ask a question here about why something doesn't work or why it worked and now it doesn't, you have to provide a schematic and your program, otherwise it's "yeah, sure, something might have gone wrong". With a schematic and source code, we might be able to point out the problem, possibly offer a suggestion for fixing whatever it is if it isn't permanent.

kutalinelucas

Fair comment. I was going from page 150 in the parallax 'stamp works' document, where the circuit and code are identical, except I have taken out the variable resistor, which is used to control speed and direction of a stepper motor through a bs2 chip and L293D driver.

Theres only been 9v supplied to the circuit, and it only seems to be 2 pins held high, the other pins toggle ok, and I was just wondering if it maybe a common problem with stamp processors, as the program loads fine onto a different bs2 chip...

PJAllen

The Stamps are well-designed, time-tested you might say; there's no "common problem".

Stampworks (V2) p.150 is Experiment #27: Stepper Motor Control.
There's no variable resistor, that's with the ADC experiments which immediately follow.

Maybe it's the schematic, the depiction/routing of V_dd?
I re-configured that in the attached dwg to sort of disambiguate the layout. V_dd should not be connected to any of the Stamp I/O pins, in the original it should be understood that V_dd runs over/under P4,5,6.