Need Help, Servo Activity #3 Problem Chap 4 "What's a MicroController?"

mchisti · 2012-02-04 10:55

I'm doing Activity #3 in the What's a MicroController and was doing great, till I had to hold different positions for servo. I wrote the code exactly the way the text has it written (which is the copy you see below) and it doesn't work. When I execute the code, servo just twitched to the right about 2 degrees every one second. That gives me the feeling that the "PAUSE 1000" must somehow affect the servo in the FOR NEXT. I also know that it ignores the counter Variable because servo keeps displaying "Position = 45 degrees" on the terminal way after 15 times ( 150/50 = 15 ). Can someone help me? I tried putting the whole FOR NEXT inside the a DO LOOP and then tried nesting DO LOOP inside of FOR NEXT, then tried both :thumb:, but it did the same PAUSE 1000 twitch to the right by 2 degrees again.

The problem is, It just gets stuck and doesn't position it's self. The code is suppose to let servo rotate to 45 degrees, hold position for 3 seconds, then rotate to 90 degrees, hold for 3 secs, rotate to 135 degrees and hold for 3 secs, then code END.

Thank You

' {$STAMP BS2}
' {$PBASIC 2.5}

counter VAR Word

PAUSE 1000

DEBUG "Position = 45 degrees...", CR

FOR counter = 1 TO 150
PULSOUT 14, 500
PAUSE 20
NEXT

DEBUG "Position = 90 degrees...", CR

FOR counter = 1 TO 150
PULSOUT 14, 750
PAUSE 20
NEXT

DEBUG "Position = 130 degrees...", CR

FOR counter = 1 TO 150
PULSOUT 14, 1000
PAUSE 20
NEXT

DEBUG "All done.", CR, CR

END

PJAllen · 2012-02-04 11:28

You're using a BoE or HWB or what?
The BoE switch has to be all the way over to the right. (There's Off - On - Servos_On)

It should hold each position for approx 3 sec.

' {$STAMP BS2}
' {$PBASIC 2.5}

counter VAR Word

PAUSE 1000

Routine:
  DEBUG "45", CR

  FOR counter = 1 TO 150
    PULSOUT 14, 500
    PAUSE 19
    NEXT

  DEBUG "90", CR
  FOR counter = 1 TO 150
    PULSOUT 14, 750
    PAUSE 19
    NEXT

  DEBUG "130", CR

  FOR counter = 1 TO 150
    PULSOUT 14, 1000
    PAUSE 19
    NEXT

  GOTO Routine

Duane Degn · 2012-02-04 11:48

What are you using for a power supply.

keeps displaying "Position = 45 degrees" on the terminal

Makes me think your Stamp keeps resetting when the servo tries to move. This is a very common problem when trying to drive servos. They pull a lot of current when they start to move which causes the voltage to drop, which in turn resets the microcontroller.

You need a good power source (not a 9V battery). A wall-wart transformer might work but I've had better luck with a good rechargable battery pack.

mchisti · 2012-02-04 14:55

It was a Homework Board.

Duane Degn wrote: »

What are you using for a power supply.

Makes me think your Stamp keeps resetting when the servo tries to move. This is a very common problem when trying to drive servos. They pull a lot of current when they start to move which causes the voltage to drop, which in turn resets the microcontroller.

You need a good power source (not a 9V battery). A wall-wart transformer might work but I've had better luck with a good rechargable battery pack.

Thanks a lot, it was the battery problem. I didn't use an Alkaline Battery and now I just bought one.

erco · 2012-02-04 18:50

IIRC, WAM even shows the HW board's 9V battery being used to power the servo. Convenient, but not desirable. First choice would be a seperate battery, at least 4x AA cells.

Duane Degn · 2012-02-04 19:13

erco wrote: »

IIRC, WAM even shows the HW board's 9V battery being used to power the servo. Convenient, but not desirable. First choice would be a seperate battery, at least 4x AA cells.

That's too bad WAM adds to the problem of people under powering their servos. It seems like this problem comes up at least once a week on the fourm.

Need Help, Servo Activity #3 Problem Chap 4 "What's a MicroController?"

Comments