Data Sheet

ManualsBrandsParallax ManualsMisc. Servo MotorsParallax Feedback 360° High Speed Servo

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Technical: support@parallax.com

Office: (916) 624-8333

Fax: (916) 624-8003

Sales: (888) 512-1024

Tech Support: (888) 997-8267

Parallax Feedback 360° High-Speed Servo (#900-00360)

The Parallax Feedback 360° High Speed Servo provides the functionality of a light-duty standard servo,

continuous rotation servo, high-speed servo, and encoder in one convenient package.

most servos, the Feedback 360° is controlled by a 50 Hz PWM signal. What sets it apart is a return

signal line from an internal Hall effect sensor system that provides digital angular position feedback.

Utilizing this feedback signal, your application can make the servo to turn to and hold any angle, much

like a standard servo but with an unlimited range of motion. Or, rotate the servo continuously at a

controlled, verifiable speed as a robot drive motor. Control signal

response is nicely linear across the speed control range.

locklyProp blocks and user-friendly C Propeller C libraries are in the

works. Low-level position control example C code is discussed in this

guide.

Features

● Bidirectional, continuous, feedback-controllable, low-load rotation

fro

m -120 to 120 RPM

● PWM positional feedback across entire RPM range

● Internal Hall effect position sensor not subject to wear or sensor

deadband as are potentiometer-style feedback systems

● No need to manually “center” the servo

● 3-pin ground-power-signal cable plugs onto the Activity Board’s 3-

pin header

● Separate single wire with female connector supplies feedback to

an I/O pin

Specifications

● RPM: 120 w/feedback control, 140 max (+/- 15) @ 6 V, no load

● Gears: POM

● Case: Nylon & fiberglass

● Spline: 25-tooth, 5.96 mm OD

● Peak stall torque @ 6 V: 2.5 kg-cm (34.7 oz-in)

● Voltage requirements: 6 VDC typical, 5–8.4 VDC max range

● Current requirements: 15 mA (+/- 10) idle, 150 mA (+/- 40) no-load, 1200 mA stalled

● Control signal: PWM, 3–5 V 50 Hz, 1280–1720 µs

● Control signal zero-speed deadband: 1480–1520 µs (+/- 15)

● Feedback sensor: Hall effect

● Feedback signal: PWM, 3.3V, 910 Hz, 2.7%–97.1% duty cycle

● Product weight: 1.4 oz ( 40 g)

● Cable length: ~ 9.8 in (250 mm)

● Dimensions: approx. 2.15 x 1.46 x 0.79 in (50.4 x 37.2 x 20 mm)

● Mounting hole spacing: 10 x 49.5 mm on center

● Operating temperature range: 5 to 158 °F (-15 to +70 °C)

Resources and Downloads

Check for the latest version of this document, free software, and example programs from the Feedback

360° High-Speed Servo product page. Go to www.parallax.com and search 900-00360.

Summary of content (7 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 Feedback 360° High-Speed Servo (#900-00360) The Parallax Feedback 360° High Speed Servo provides the functionality of a light-duty standard servo, continuous rotation servo, high-speed servo, and encoder in one convenient package.
PAGE 2
Quick-Start Circuit Pin Descriptions Pin Name Description Min Yellow Feedback Servo output, PWM, 910 Hz, 2.7–97.1% duty cycle White Control Red Vservo Typical Max 3.3 Units V Servo input, PWM, 50 Hz, 1280–1720 µs 3.3 3.3 5.0 V Servo power supply 5* 6 8.4 V Black Vss Ground, common ground with microcontroller 0 v *5 VDC is absolute minimum required for no-load angular position control. 5.8 to 8 VDC is recommended for continuous rotation speed control.
PAGE 3
The rotational velocity response to tControl is fairly linear. This example graph is for 6.3 V, no load. Feedback Signal The servo sends a feedback output signal to your microcontroller via the yellow wire connection. This signal, labeled tCycle in the diagrams and equations below, has a period of 1/910 Hz (approx. 1.1 ms), +/- 5%. Within each tCycle iteration, tHigh is the duration in microseconds of a 3.3 V high pulse.
PAGE 4
For example, a rolling robot application may use 64 units, or “ticks” per full circle, mimicking the behavior or a 32-spoke wheel with an optical 1-bit binary encoder. A fixed-position application may use 360 units, to move and hold the servo to a certain angle. The following formula can be used to correlate the feedback signal’s duty cycle to angular position in your chosen units per full circle. Duty Cycle = 100% x (tHigh / tCycle). Duty Cycle Min = 2.9%. Duty Cycle Max= 97.1%.
PAGE 5
This code allows you to enter angles into the terminal, and displays the servo’s progress as it turns to its target position. while(1) { print("Enter angle: "); scan("%d", &targetAngle); print("\r"); while(abs(targetAngle - angle) > 4) { print("targetAngle = %d, angle = %d\r", targetAngle, angle); pause(50); } } Position detection The code from the feedback360 function needs to be repeated rapidly, at least every ¼ turn, but between every servo pulse (50 Hz) is recommended.
PAGE 6
theta was in the first quadrant, and the new theta is in the fourth quadrant, we know that the angle transitioned from a low to high value, so decrease the turns count.
PAGE 7
This uses the output and offset values to set the servo speed. When the error is large, the output will be large, up to 200. If there is any error, the offset will be 30 for + error or -30 for - error, or 0 for no error. So the resulting output will range from 30 to 230 for positive, counterclockwise correction, or 30 to -230 for negative, clockwise correction. servo_speed(pinControl, output + offset); After a 20 ms (1/50 s) delay, the loop repeats. pause(20); Module Dimensions Revision History Version 1.