hitec hs-755hb servo

markallen

hello, i'm trying to control a hitec hs-755hb servo with my bs2 stamp. whatever pulsout commands I send it slowly rotates all the way around and then stops. I've tested the circuit with a standard servo from parallax (it works fine), I've also tried changing the pulsout values. I've also noticed the 7805 I'm powering it with is getting very hot, although the servo is only supposed to draw 250 ma

I'm using the following as test code, with changes to the pulsout command to see if different pulses have an affect.

servopin con 8
x var byte

main:
for x = 1 to 20
pulsout servopin, 300
pause 20
next

for x= 1 to 20
pulsout servopin, 1500
pause 20
next
goto main

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here are the specs I have on the servo



ontrol System: +Pulse Width Control 1500usec Neutral
Required Pulse: 3-5 Volt Peak to Peak Square Wave
Operating Voltage: 4.8-6.0 Volts
Operating Temperature Range: -20 to +60 Degree C
Operating Speed (4.8V): 0.28sec/60 degrees at no load
Operating Speed (6.0V): 0.23sec/60 degrees at no load
Stall Torque (4.8V): 153 oz/in. (11kg.cm)
Stall Torque (6.0V): 183 oz/in. (13.2kg.cm)
Operating Angle: 45 Deg. one side pulse traveling 400usec
360 Modifiable: Yes
Direction: Clockwise/Pulse Traveling 1500 to 1900usec
Current Drain (4.8V): 8mA/idle and 230mA no load operating
Current Drain (6.0V): 8.7mA/idle and 285mA no load operating
Dead Band Width: 8usec
Motor Type: 3 Pole Ferrite
Potentiometer Drive: Indirect Drive
Bearing Type: 1 Bearing and 1 Oilite Bushing
Gear Type: Karbonite Gears
Connector Wire Length: 11.81" (300mm)
Dimensions: 2.3" x 1.1"x 2.0" (59 x 29 x 50mm)
Weight: 3.88 oz.. (110g)

Chris Savage

Which BASIC Stamp are you using?· I know for starters you're not giving it enough time to go from one extreme to the other and then immediately go to the opposite extreme.· It's a wonder it's not stuttering.

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Chris Savage
Parallax Tech Support
csavage@parallax.com

markallen

Hi, I'm using a basic stamp 2.

I put a pause in between and it did not help - the servo moves clockwise regardless of what pulse is sent to it.

Chris Savage

Okay, first add a line that says LOW 8 before you start pulsing out, and change first value to 500 and the second to 1000, change your FOR...NEXT loop to go from 1 to 200 instead of 20.· See what happens then.· Oh, and how are you powering this setup?· And what wires on the servo are connected where?· I wonder if you have a common ground between the Stamp and the Servo and it's power supply.

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Chris Savage
Parallax Tech Support
csavage@parallax.com