Elf - my RoboPi + Raspberry Pi + 2WD Magician + WiFi Robot

Meet Elf - one of my RoboPi + Raspberry Pi based robots!

I have a lot of the Magician 2WD chassis, and I thought it would be the perfect platform to evaluate inexpensive low power motor driver modules.


  • RoboPi
  • Raspberry Pi
  • WiFi stick
  • Magician 2WD chassis
  • L9110S driver module
  • breadboard - jumper wires
  • HC-SR04 ultrasonic range sensor

Assemble & start playing :)

Right now, ELf is pretty simple, but I have this nice Raspberry Pi camera module for him...

More photos etc on the build log page at http://www.mikronauts.com/robot-zoo/elf-2wd-pi-robot/

I'd be happy to answer your questions about Elf here!

Tue Aug.14, 2014 Update

I am using Elf to test out my new Python library for RoboPi. So far so good :-)

Barring unforseen issue, I expect to release the v0.85 firmware/libraries/documentation next week, inlucding Python support.

This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/elf-my-robopi-raspberry-pi-2wd-magician-wifi-robot


so far - so good. Here isa random walk snipped:

# main program


for motor in range(lfwd,rrev+1):
    RoboPi.pinMode(motor,isa.OUTPUT) # set motor control pins to output

while (1):
    while (RoboPi.readDistance(sonar) > 200):
    while (RoboPi.readDistance(sonar) < 201 ):




I’m working on my Magician chassis right now, though I’ll have to chop off a bit to make it balance.

Where can you buy them in blue?

Blue 2WD Magician

Thank you!

I make mine balance using the weight of the battery packs.

I ordered them a couple of years ago, I still have about 50 of the blue 2WD in stock.

I was trying to make a
I was trying to make a balancing bot out of them. Unfortunately this didn’t work, so I’m working on plan C now.

Thank you. And here I was hoping to get a new red, green, and blue one. I guess I’ll have to print something for that idea when my printer is finally shipped and wends it slow way here. It will probably arrive real soon now when I can’t do anything with it because Lee needs surgery and I have to take her to Cleveland.

My best wishes for Lee

I hope the surgery goes well!

I am not sure how well those yellow gear motors would work for a balancing bot, so please let me know if it works.

If you can’t find it in the states, and you need a blue one, pm me.

major Elf updates :slight_smile:

I was finally able to make some time to update my Elf build log :slight_smile:

  • wiring info and photos for the L9110S motor driver
  • wiring info and photos for the HC-SR04 range sensor
  • sample Python code for RoboPi controlling the motor driver via PWM and reading the range sensor

Elf: http://www.mikronauts.com/robot-zoo/elf-2wd-pi-robot/
RoboPi: www.mikronauts.com/raspberry-pi/robopi/

I welcome your questions and feedback!

Elf update: Raspberry Pi Camera & WiFi streaming

Today I’ve updated my Elf Raspberry Pi based robot’s build log with instructions on:

  • adding a Raspberry Pi Camera
  • adding MJPG-Streamer so Elf streams what he sees over WiFi
  • adding a ramdisk for MJPG-Streamer so it won’t wear out the SD card

I hope you enjoy the Elf blog, and please feel free to ask any questions!

Elf Article Index