Datasheet

ManualsBrandsParallax ManualsAutomationServo Motor 268.3 Nmm 50 min -1 140 mA

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Parallax Continuous Rotation Servo (#900-00008)

The Parallax Standard Servo is ideal for adding bidirectional continuous rotation to your robotics projects.

Features



Bidirectional continuous rotation

 0 to 50 RPM, with a linear response to PWM for easy

ramping

 Accepts four mounting screws

 Easy to interface with any Parallax microcontroller or

PWM-capable device

 Very easy to control with the PULSOUT command in

PBASIC or SX/B

 Weighs only 1.50 oz (42.5 g)

 38 oz-in torque @ 6 V

Key Specifications



Power requirements: 4 to 6 VDC; Maximum current draw

140 +/- 50 mA at 6 VDC when operating in no load conditions, 15 mA when in static state

 Communication: pulse-width modulation

 Dimensions: approx 2.2 x 0.8 x 1.6 in (5.58x 1.9 x 4.06 cm) excluding servo horn

 Operating temperature range: 14 to 122 °F (-10 to +50 °C)

Quick-Start Circuit

Vµ = microcontroller voltage supply

Vservo = 4 to 6 VDC, regulated or battery

I/O = PWM TTL or CMOS output signal, 3.3 to 5 V; < Vservo + 0.2 V

Continuous Rotation Servo Microcontroller

GND

Vservo

White

Vss

I/O

Red

Black

Vdd

Vµ

Summary of content (8 pages)

PAGE 1
Web Site: www.parallax.com Forums: forums.parallax.com Sales: sales@parallax.com Technical: support@parallax.com Office: (916) 624-8333 Fax: (916) 624-8003 Sales: (888) 512-1024 Tech Support: (888) 997-8267 Parallax Continuous Rotation Servo (#900-00008) The Parallax Standard Servo is ideal for adding bidirectional continuous rotation to your robotics projects.
PAGE 2
Device Information The Parallax continuous rotation servo relies on pulse width modulation to control the rotation speed and direction of the serv o shaft. Before u sing the servo in a project, it is important to c alibrate the center position of the servo in order to defi ne the pul se width value at which the servo holds still (see the section Calibration – "Center" the Servo on page 4).
PAGE 3
√ √ √ √ √ Disconnect the 9 V battery from the board, and do not put the AA batteries in their holder yet. Build the servo ports shown by the schematic and wiring diagram below. Double-check to mak e sure the black wire with th e white stripe is conn ected to Vbp , the solid black wire is connected to Vss, and that all the connections for P13, Vbp, Vss, Vbp (another one), and P12 all exactly match the wiring diagram. Connect the servo plugs to the male headers on the right side of the wiring diagram.
PAGE 4
Calibration – "Center" the Servo The servo has a pot entiometer access port, right above the plac e where the cable attaches to the c ase. The port allows the user to adjust the servo to hold completely still when receiving a 1.5 ms pulse width. This is the value in the "center" of the range of control pulses the servo will accept. To center the servo, program your host device to deliver a 1.5 ms pulse, continually refreshed ever y 20 ms.
PAGE 5
ctra[30..26] := %00100 ctra[8..0] := servoPin ' Configure Counter A to NCO frqa := 1 dira[servoPin]~~ ' Set up cycle and high times tInc := clkfreq/1_000_000 tC := tInc * 21_500 tHa := tInc * 1500 t := cnt ' Mark counter time repeat phsa := -tHa t += tC waitcnt(t) ' ' ' ' Repeat PWM signal Set up the pulse Calculate next cycle repeat Wait for next cycle Communication Protocol The Parallax Continuous Rotation Serv o is controlle d through pulse width modulation.
PAGE 6
Voltage and RPM: Maximum RPM will vary with input voltage; 50 RP M @ 5 V is typical. Using regulated Vdd as the sup ply source wi ll reduce fluct uations in RPM for a given pulse width that might otherwise occur with unregulated battery supplies. BASIC Stamp® Programming Examples PBASIC has a PULSO UT command that sets the I/O Pin to an output and sends a pulse of the specified Duration.
PAGE 7
FOR counter = 1 TO 100 ' Hold still for ~3 seconds PULSOUT servoPin, 750 PAUSE 20 NEXT FOR counter = 1 TO 100 ' Rotate clockwise for ~3 seconds PULSOUT servoPin, 650 PAUSE 20 NEXT END For more examples with the BASIC Stamp 2, incl uding 2-wheeled robot maneuvers and ramping, see Robotics with the Boe -Bot Chapter 4 , available for free downl oad from the 28132 product page at www.parallax.com.
PAGE 8
waitcnt(t) repeat 100 phsa := -tCcw t += (tC - 200) waitcnt(t) ' Wait for next cycle (20 ms) ' ' ' ' Repeat PWM signal 100x Set up counter-clockwise fast pulse Calculate next cycle repeat Wait for next cycle (20 ms) Revision History Version 2.1: corrected values in BASIC Stamp Model PULSOUT table; updated example programs to use a constant for the servo pin. Version 2.2: added Voltage and RPM note on p age 6. Added Usin g a Separate Power Supply on a HomeWork Board section beginning on page 2.