Photosensors,Bad pins, and PC connection
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Posts: 46,084
Paul,
> I'm using three cadmiun sulfide photo conductive cells to move 2
> steppers. How can i get a value from each cell to compare to the
> other
> values of the other cells? Can i use RCTIME and asign a value to a
> varible? Is there any A/D conversion that needs to be done?
RCTIME is a crude A/D conversion, and will do what you need for relative
numbers.
> I let someone do a little testing with my stamp and i think he may of
> fired two pins. I tell them to output to an LED and nothing happens.
> Is there any other way i can tell?
That is a pretty conclusive test. PICs are tough, but they are not
invulnerable. Something as simple as a 220 ohm resistor in series with
the RC load or stepper motor is all that is needed to current protect a
Stamp pin.
> Last question:
> After i hit the run button on the Stamp II program, the STamp should
> then work indepently. But if i dissconnect the serial cable from the
> stamp everything stops and is shut down, and i can't get the stamp to
> respond. I don't get it.
Check your grounds, that is usually the source of these problems. Also,
your Stamp may reset when you remove the cable, the ATN line could get toggled.
Something else you will need to do. When comparing two CDS sensors, they
need to be combined with a capacitor to do the RCTIME reading. If you want
precision, make sure to get close tolerance caps. Also, you will need to
define a "dead band" in your readings because the two cells will NEVER be
the same value! This will help to avoid jitter at the boundries of decision.
have fun,
DLC
--
============================================================================
* Dennis Clark Aristocrat at heart dlc@v... www.verinet.com/~dlc *
* Be well, do good work, and stay in touch -- Garrison Keillor *
============================================================================
> I'm using three cadmiun sulfide photo conductive cells to move 2
> steppers. How can i get a value from each cell to compare to the
> other
> values of the other cells? Can i use RCTIME and asign a value to a
> varible? Is there any A/D conversion that needs to be done?
RCTIME is a crude A/D conversion, and will do what you need for relative
numbers.
> I let someone do a little testing with my stamp and i think he may of
> fired two pins. I tell them to output to an LED and nothing happens.
> Is there any other way i can tell?
That is a pretty conclusive test. PICs are tough, but they are not
invulnerable. Something as simple as a 220 ohm resistor in series with
the RC load or stepper motor is all that is needed to current protect a
Stamp pin.
> Last question:
> After i hit the run button on the Stamp II program, the STamp should
> then work indepently. But if i dissconnect the serial cable from the
> stamp everything stops and is shut down, and i can't get the stamp to
> respond. I don't get it.
Check your grounds, that is usually the source of these problems. Also,
your Stamp may reset when you remove the cable, the ATN line could get toggled.
Something else you will need to do. When comparing two CDS sensors, they
need to be combined with a capacitor to do the RCTIME reading. If you want
precision, make sure to get close tolerance caps. Also, you will need to
define a "dead band" in your readings because the two cells will NEVER be
the same value! This will help to avoid jitter at the boundries of decision.
have fun,
DLC
--
============================================================================
* Dennis Clark Aristocrat at heart dlc@v... www.verinet.com/~dlc *
* Be well, do good work, and stay in touch -- Garrison Keillor *
============================================================================