BB servo direction trouble?

GerryL

·· I decided to take advantage of the rebate deal for a Boe-Bot, and I jumped right in when I received it.· Everything was going well until tonight.· I ran into trouble when entering the program TestServoSpeed.bs2.· Last week I ran BoeBotServoTest.bs2·and BothServosThreeSeconds.bs2; everything was fine.· Tonight I worked up to TestServoSpeed.bs2, and I couldn't get the servos to rotate in opposite directions!· They both appear to run about the same speed, but in the same direction.· I triple checked the program, then added the line
DEBUG CR, ? pulseWidth, ? pulseWidthComp
to be sure that the math was coming out right.· Still no luck.
I went back to BoeBotServoTest.bs2, and that was fine.· Then I moved up to BothServosThreeSeconds.bs2 and had a problem; both servos turned in the same direction.· The same occured again when I loaded TestServoSpeed.bs2 again.· It appears that when both pins 12 and 13 are told to go at the same time, I have the problem.· When used separately, they are ok.· I am using the (4) AA battery pack on the Boe-Bot.· Has anyone seen this before?· Any ideas?
Thanks!· -Gerry
·

allanlane5

Sounds almost like a solder bridge shorting two pins together -- but with Parallax BOE boards, that almost NEVER happens. Could be, I suppose.

GerryL

OK, here's more info (or clearer info).

It appears that any pulsout value on pins 12 and 13 works properly if they are turned on one at a time (for driving servos).· If I run both pin 12 and 13 at the same time, it appears that both servos follow the first pulsout command value.·

Does this seem hardware related?· I'm confused, because I didn't change anything physically on the Boe-Bot...I just took a break over the weeekend/holiday.· Booted up the computer, put in the new program and ran into trouble.

Any Ideas?

· -GerryL

Jon Williams

Remove the BASIC Stamp from the board and disconnect power. Check to see if there is a short between pins 12 and 13.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax
Dallas Office

GerryL

Thanks for the assistance guys...it appears I was up way too late last night and had a *MAJOR* brain lapse.·· I got home from work today and was bound and determined to figure out the problem.· I pulled the BS2, checked for shorts, none anywhere.· Put it back together, same problem.· I borrowed another BS2/BOE from another project, same thing...HEY, wait a minute...
Right about now I need an emoticon with egg on it's face!
The BOE BOT wheels are turning in the same direction (as they are supposed to), and the servos·ARE turning in opposite directions.·
For some reason last night I was convinced that my Boe Bot should be turning in circles running this program.
·
-Gerry