OpenServo Hardware

The OpenServo hardware is documented in the links below.

attachment:pcbs.jpg OpenServoV2?action=AttachFile&do=get&target=tutorial_010 FrontPage?action=AttachFile&do=get&target=openservo OpenServoV3?action=AttachFile&do=get&target=osv3_top_big

OpenServo 3.0 Information

Main page: OpenServoV3. Summary:

OpenServo 3.0 is the latest version of the OpenServo hardware based on the AVR ATmega168 MCUs. This MCU has 16K of Flash allowing more features to be implemented. This version of the OpenServo also uses independent bridge control and back EMF sensing.

Schematic: OpenServo 3.0 schematic diagram
Datasheets: relevant datasheets
OpenServoPinout

Download the whole Cliff Huston OpenServo V3 package here: OS3v3_Bd_7_19_2007.zip

Includes PCB, schematics, BOM and documentation.

OpenEncoder

Open Encoder (OpenEncoder) is a digital I2C full rotation position feed back device, designed to replace the position-sensing pot that came with the servo.

SparkFun OpenServo ROB-09014

What is this SparkFun OpenServo ROB-09014?

OpenServo 2.1 Information

Main page: OpenServoV2. Summary:

This is the stable version of the OpenServo hardware based on the AVR ATmega8 and AVR ATmega168 MCUs. These MCUs have 8K and 16K of Flash respectively allowing more features to be implemented. This version of the OpenServo also uses International Rectifier IRF7309 MOSFET (or equivalent) for greater current capacity.

Schematic: OpenServo 2.1 schematic diagram
Printed Circuit: OpenServo 2.1 printed circuit diagram
Parts List: OpenServo 2.1 parts list
Parts Placement: OpenServo 2.1 parts placement
Datasheets: relevant datasheets

OpenServo 1.1 Information

OpenServo 1.1 is based on the AVR ATtiny45 MCU with 4K of Flash. Unfortunately, the AVR ATtiny85 MCU with 8K of Flash has not yet been released by Atmel. Because of the limited Flash memory the ATtiny45 version of the OpenServo is considered to be obsolete. This design may be resurrected if and when Atmel finally releases the ATtiny85.

edit: The ATtiny85 has been officially released, and is available through Digikey. Updates to v1.1 are being made at this time and will be hosted here shortly.

Development Tools: tools used to develop OpenServo hardware
Schematic: OpenServo 1.1 schematic diagram
Printed Circuit: OpenServo 1.1 printed circuit diagram
Parts List: OpenServo 1.1 parts list
Parts Placement: OpenServo 1.1 parts placement
Datasheets: relevant datasheets
Testing: hardware and tools related to testing
Assembly Notes: notes relating to assembly

earlier servo replacement PCBs

A few other people have developed PCBs vaguely similar in one way or another to OpenServo PCBs.

Colin MacKenzie provided the original inspiration for the development of the OpenServo. Colin developed a similar servo board called the SuperServo for his Symapod robot using the PIC16C73A and was kind enough to share his design. Aspects of Colin's hardware design were borrowed for the OpenServo.

Six transistor H-Bridge PCB replacement for servo PCB is a much simpler internal servo PCB replacement board.

The Netmedia 8T servo controller provides live torque/load information for each attached servo. http://www.robotshop.us/netmedia-8t-super-servo-controller.html http://www.basicx.com/Products/servo/servo8t.htm

On the "Molecubes For Everyone" wiki, the "Assembly of an Actuator Molecube" briefly shows a servo controller PCB that looks suspiciously similar to an OpenServo.

The Robot Room: Monkey Mints Robot by David Cook uses a Atmel ATtiny85 AVR. We probably would have used the same MCU for OpenServoV2 and OpenServoV3 but it was not yet available then. See the "ATtiny45 vs. ATtiny85" thread for details.

Servo Hardware Information

Servo Hardware: photos and information on servo hardware