servo control

froslie · 2005-08-27 20:53

I am considering getting into the Sx. I am familiar with the BS2.

Can anyone tell me how easy it would be to control simple I/O relationships? For insatnce I would like to control a servo from a sensor.

If this is fairly easy to get at, it would seem on a very basic level to be a very cost effective solution over the BS2.

thank you

Beau Schwabe · 2005-08-27 22:04

If you compare the BS2 to SX/B (< the "Free" Pbasic compiler for the SX), then the code is virtually the same.

Code for the BS2 to pan a servo back-n-forth

' {$STAMP BS2p}
' {$PBASIC 2.5}

ServoPin  CON 0
ServoMin  CON 1250  'equals 1mS at 0.8uS resolution
ServoMax  CON 2500  'equals 2mS at 0.8uS resolution
ServoTemp VAR W1

LOW    ServoPin
OUTPUT ServoPin

MainLoop:

FOR ServoTemp = ServoMin TO ServoMax STEP 10
    PULSOUT ServoPin,ServoTemp
    PAUSE 20
NEXT
FOR ServoTemp = ServoMax TO ServoMin STEP 10
    PULSOUT ServoPin,ServoTemp
    PAUSE 20
NEXT

GOTO MainLoop

Code for the SX to pan a servo back-n-forth

DEVICE          SX28, OSC4MHZ, TURBO, STACKX, OPTIONX
FREQ            4_000_000


ServoPin  VAR RB.0
ServoMin  CON 100   'equals 1mS at 10uS resolution
ServoMax  CON 200   'equals 2mS at 10uS resolution
ServoTemp VAR Byte

 LOW    ServoPin
 OUTPUT ServoPin

MainLoop:

FOR ServoTemp = ServoMin TO ServoMax STEP 1
    PULSOUT ServoPin,ServoTemp
    PAUSE 20
NEXT
FOR ServoTemp = ServoMax TO ServoMin STEP 1
    PULSOUT ServoPin,ServoTemp
    PAUSE 20
NEXT

GOTO MainLoop

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

servo control

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