My son and I thought it would be fun project to build a meArm robot arm. If you haven’t heard of the meArm, go check out their website, or download the files to make your own over on thigiverse.
The brains board that meArm sells for controlling the thing is pretty pricey, so we thought we would just design our own. The setup is actually two boards. The larger board is processor board, and the smaller one is the joystick board.
The processor board will attach to the meArm base, and uses a cheap Arduino Pro Mini clone that you can get off ebay for around $3, to controll the servos. The processor board also has a few extra IO pins that could be used for extra servos (I’m thinking of a base with two continuous rotation servos driving wheels) or other sensors, and a IR receiver so that it can be controlled with a IR remote such as your TV remote, or the LEGO power function remote.
The small board is the joystick board. It accommodates 2 analog joysticks and 3 push buttons. The joystick board is connected to the processor board with a ribbon cable.
I designed the boards up in Altium, and I’m in the process of converting the files over to CircuitWorks so that I can release them, so stay tuned if you are interested in using the design.
UPDATE May 15 2013: Split is now available for sale on our website
We’ve been slowly working away on an Arduino based wireless module called “Split” and just got the first real prototypes assembled and working over the last week. The module is based around a Atmega328P and a RFM22B wireless module, so it is kind of like a cross between a Arduino Pro Mini and a RFM22B breadout board.
Specs and Features:
Operating voltage: 3.3V
Processor: Atmega328P with Arduino bootloader
RF Frequency Range: 433MHz, 868MHz, or 915MHz ISM band (depending on version)
RF data rate: adjustable from 0.123 to 256kbps
RF output power: adjustable from 1 dBm to 20 dBm
RF receive sensitivity: -121 dBm
Long range up to several Km with proper antennas
On board 3.3V regulator
PCB Size: 20mm x 38mm
All processor IO pins are brought out to header pins
Programmed with FTDI Pro
A user LED and button connected to IO pins
Slide switch to allow the DTR signal from the FTDI Pro to be directed to an IO pin to allow programming of a remote Arduino processor
Split RF module connected to a FTDI Pro
There are three main ways we envisioned Split being used:
As a standalone processor with wireless capability.
As a generic wireless UART link with remote DTR control to allow communicating with and programming of a Arduino processor attached to the remote Split module.
As a wireless IO link. Input pins on one end are mapped to output pins on the other end and vice versa.
We’ve done some initial testing with the RF22 library from open.com.au and it seems to work so that covers #1, and we are in the process of writing firmware for #2 and #3.
We are pretty excited about the long range wireless capabilities Split will give to a lot of projects.
Split RF module connected to the Mongoose IMU
If you are interested in this project, leave some feedback or a comment. Once we know how much interest there is, we can make some better plans for a release date.
The first version of the Mongoose AHRS (Attitude and Heading Reference System) firmware and the PC GUI (with VB.net source code) are both working and are available for download on the website. There is still a bit of work that needs to be done to make sure the soft iron compensation is working, but for the most part it is working pretty well.
Mongoose – the 9 DOF IMU with barometric sensor, and lots of other cool features – is almost ready for launch!!
We based our design on the popular Sparkfun Razor, updated the magnetometer, added a barometric pressure sensor, and improved utility and usability with a few other design features.
We’ve also taken the AHRS firmware written by Jordi Munoz and updated it to support the new gyro, magnetometer and the addition of the barometric pressure sensor. Also, we have a Windows GUI for showing all the sensor data as well as attitude and heading in real time.