Reducing noise so processor won't reset
chronister
Posts: 17
Have you ever heard of the stamp resetting because of motor noise? I have noise suppression capacitors on my motors, but the stamp and motors are both driven by the same 7.4 battery. Therefore when the motors run, some kind of noise in the·battery supply causes the stamp to reset. Due to weight restrictions I cannot use separate batteries (and button cells are not a practical solution).·Is there some way I can filter the supply voltage so this won't happen?
(I am using Al Williams PAK coprocessors and the two motors are pulse width modulated for speed control.)
Thank you for your help!
Nathan
(I am using Al Williams PAK coprocessors and the two motors are pulse width modulated for speed control.)
Thank you for your help!
Nathan
Comments
do you have an oscilloscope to check the amount of noise.
the start of the motors plus whatever else your running on those batteries could be enough to pull it below the stamps brown-out
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
DTQ
I have used a bridge rectifier in the past. Tie the AC terminals on the bridge to the motor,
tie the +(pos) on the bridge to your battery +(pos) and the -(neg) on the bridge to the battery -(neg)
Also you might use a diode capacitor filter to your uP circuitry.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe - Mask Designer III
National Semiconductor Corporation
(Communication Interface Division)
500 Pinnacle Court, Suite 525
Mail Stop GA1
Norcross,GA 30071
3300uf or larger on the positive lead of your battery.· You may have to go to a different power supply for your Stamp.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Sid Weaver
Do you have a Stamp Tester?
http://hometown.aol.com/newzed/index.html
·
You can probably prove this by putting almost any decent sized battery of the same voltage in parallel with the existing one and they trying it again. If it doesn't fail then, the problem is over-current causing a low voltage brown-out and not noise.
Regards,
Bruce Bates
Just power the stamp separately and you should be able to see if it works!
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·
Steve
http://members.rogers.com/steve.brady
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
"Also you might use a diode capacitor filter to your uP circuitry."
Is a "diode capacitor filter" the same sort of circuit I have on my motor? What's "uP"?
Sid, you suggested a capacitor on the + battery lead. Did you mean that it should be across the battery leads?
I'll try it with a separate battery for test purposes. I should connect the grounds together, right?
·· "uP" = Micro-Processor...Or, more appropriately, your BASIC Stamp.· Usually written as µP, but the µ is hard for many to add to posts, since it's an extended character.
· As for the Capacitor across the leads, if you use a large electrolytic capacitor, you would tie the ends directly to the power leads.· This will provide somewhat of a reserve for surges on the power leads.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
--==<{Chris}>==--
A bridge rectifier is simply an arrangement of 4 diodes that can easily redirect an AC voltage into a DC
voltage. In your case the AC voltage would be in the form of back EMF or "free wheeling" from the motor
acting as a generator being directed back into the power supply.
I've included a "diode capacitor" filter that may be a bit over kill, but it should get the job done for most other
applications where noise is a problem.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe - Mask Designer III
National Semiconductor Corporation
(Communication Interface Division)
500 Pinnacle Court, Suite 525
Mail Stop GA1
Norcross,GA 30071
What's their internal resistance?
And do they react immediately?
(Some types of batteries can't deliver the full amperage immediately)
I know that there are Lead-Acid batteries approx the same size as 'D-Size' cells that can deliver 400A instantly, but I believe those are the exception to the rule...
(Found them in an old HP 110 portable... )