This is our version of the AVR microcontrolled UHU servo board designed by Uli Uber. It is a brushed motor controller with step/direction interface. It is capable of 250,000 steps/second for fast motor rpm. More information about the servo controller can be found at Uli’s web site FAQ , Wiki page, our FTP site and this CNCZONE thread.

UHU Servo

Uhu servo boards are now available.

UHU Servo schematic (.pdf), layout (.pdf) and parts list (.pdf). Wiring Schematic (.pdf)
UHU Servo silkscreen layout by part number (.pdf)

Atmel AVR ATtiny2313 microcontroller based.
Drives standard brushed servo motors with encoders using an enhanced PID algorithm.
PWM current and speed control for quiet motor running.
Using standard IRF540N FETs, 60volt 20amp servo motors can be driven by the servo board. Higher output current and voltage can be utilized by installing more rugged TO-220 size FET’s.*
Adjustable servo motor current limit.
Optoisolated step and direction inputs.
Up to 250,000 steps/second for fast motor RPM.
Emergency STOP and ERROR terminals.
Parameterized P-I-D, adjustable tracking error and step multiplier via serial interface. Parameters stored in EEPROM
Onboard 5Volt regulator for encoder.
4x quadrature decoder interface.
Realtime graphical software provided for servo tuning.
LED indicators for power, OK, error and current limit.
Professional high quality double sided board with solder mask and silkscreen, made in USA.

Other features that we have added include:
Smaller sized board than the original UHU version.
FETs are placed on edge of board for easier heatsinking.
Onboard reset chip for AVR.
STK200 compatible AVR 10pin programming header. For DIY MAKER’s who want to “roll thier own” custom motor controller application. Our servo board is a great place to start.
Isolated ground between the opto and rest of the circuit board.
Separated digital and analog power section for better noise immunity.
Ground plane provided around analog power section.
External DB9 serial connector for easier case mounting.
Connector for hooking up larger external motor supply capacitors.

Also available is a parallel port breakout board and is compatible with our opto-isolated breakout board.

*UHU board has only been tested with IRF540N FET’s at 60volt/20amps. Using any other type of fet driver and/or higher voltage or current is the sole responsibility of the end user. Using high voltage and currents is dangerous. Building and using the UHU servo board is at your own risk. Embeddedtronics cannot be held liable or responsible or will accept any type of liability in any event, in case of injury or even death by building and/or using or misuse of this device or any other high-voltage device posted on this web site. By accessing, reading, and/or printing the articles presented here you agree to be solely responsible as stated in the above disclaimer and exempt Embeddedtronics from any criminal and/or liability suit. Safety is a primary concern when working with high voltage circuits.

3.75″ x 3″.

Power requirements:
Requires external regulated 12volt DC supply.

Bare PC Servo board: $10 each. (New pricing !)
No assembled units or parts kit are available.

The preprogrammed AVR microcontroller must be purchased directly from Uli Huber. We do not carry the chips.

Please include $5 shipping and handling for destinations within the continental United States. For all other areas, please include $7 for shipping charges.

For those only interested in purchasing a single bare pcb board, shipping and handling can be avoided by sending us the cost of the pcb and include a self addressed stamped envelope with your order. Please attach three first class stamps to the envelope with your legible return address. We suggest using cardboard floppy disks envelopes that can be purchased at office supply stores. US only.

Testing the UHU servo board using a Minertia T01L-44 motor with 200 line encoder. Servo motor is spinning at 2600RPM

3 axis CNC gantry high speed rapid test. This shows the high performance capabilities of a small servo motor. At 300 inch/minute, the servo motor is spinning at 3000rpm. Although a similar sized stepper motor can also spin 3000 rpm or more, there is usually very little torque available to move a small cnc gantry. The Minertia servo motors are only 1.5″ diameter which is smaller than a standard NEMA17 stepper motor.

MACH3 cnc controller
Minertia T01L-44 servo motors with 200 line encoders driven by UHU Servo Motor Controllers

1/8″ V-bit carving demo
Rapid speed 125 inch/minute
Cut speed 60 inch/minute
MACH3 cnc controller
Minertia T01L-44 servo motors with 200 line encoders driven by UHU Servo Motor Controllers
Material is 5″x5″ MDF
Proxxon IB/E high speed spindle at 20K rpm

Graphic logo from hackaday.com

Short video of the CNC milling out a circuit board.

1/8″ V-bit cutter
Rapid speed 125 inch/minute
Cut speed 30 inch/minute
MACH3 cnc controller
Minertia T01L-44 servo motors with 200 line encoders
Proxxon IB/E high speed spindle at 20K rpm

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