×

SparkFun will be closed May 25, 2015 for Memorial Day. Orders placed after 2pm on Friday the 22nd will ship out on Tuesday. Thanks!

OddBot

Member Since: February 10, 2011

Country: Australia

Profile

Bio

http://letsmakerobots.com/user/1533

Role

Designer, adviser, all around bad guy.

Organizations

K.A.O.S DAGU LMR

Spoken Languages

English Chinese (kinda)

Programming Languages

Basic, C

Universities

This Universe (mostly)

Expertise

Electronics Desktop publishing breaking things

Interests

Educational Robotics Beer Goth / Geeky Girls

  • No, you are not reading it right. The ComMotion shield has it’s own 5V and 3.3V regulators. It is designed so that it can run from a seperate battery pack to the Arduino board if required.

    The 5V regulator can deliver up to 1A of current for powering sensors and the 3.3V regulator. The 33.3V regulator can deliver up to 300mA which is enough for most Xbee and WiFly modules.

    The I2C bus only draws a few milliamps through the pullup resistors.

  • The resistor was added for the Scamper robot kits which use the demo code without an Arduino board. The resistor links the I2C pullup resistors to the logic voltage.

    In a way it was an afterthought because all the development was done on a SparkFun Redboard which does not need the resistor.

    If your using an R3 Arduino board with an IO_REF pin (such as the SparkFun Redboard) then the resistor can be removed. Future revisions will have an SMD resistor and a solder link.

  • The firmware has configurations for omni and mecanum wheels because these wheels can be difficult for beginners. The ComMotion shield does all the trigonometry for you.

    Differential drive is much simpler and often only uses 2 motors (left and right). In the case of a 4 motor Rover 5 chassis with treads, the same speeds are given to the front and rear wheels for left and right. Individual motor control is the easiest way.

    The ComMotion shield firmware is written using Arduino 1.04 and programmed using a RedBoard running the ArduinoISP sample code. You can modify the firmware if you wish.

  • It depends on the terrain and the payload. The T'REX tank, like all tracked vehicles can throw a track under some circumstances but has better traction in sand, snow and mud.

    The T'REX depends on the spring tension of the suspension to keep the tracks tight but excessive payloads will cause the springs to compress. It was originally designed to have a 3S LiPo, The T'REX controller and a Raspberry Pi inside with a pan/tilt and camera up top.

    The Wild Thumper can carry bigger / heavier payloads and never throw a track but it is more likely to get bogged in sand, snow or mud.

  • Thanks for this simple tip. I’m currently developing code on an Arduino Mega 2560 currently in excess of 50K. Your tip will save me hours.

    In my experience, your code is more likely to be corrupted by a “brown out” condition (along with the bootloader).

  • Thanks Jimb0 but unfortunately that schematic is also not correct. It does not show Vin connected to the power jack via the diode.

    Neither schematic explain why I have USB power on the Vin pin when USB is the only source of power unless it is feeding back (from OUT to IN) through the LM1117.

  • I’m designing a shield for use with your board and noticed that when powered by USB only, I am getting power on the Vin pin. I looked at your schematic but your schematic is missing some components such as the LMV358. Can you update your schematic please.

  • With the prototype I used a 5000mAh 3S Lipo. It all depends on what kind of run time you want between charges.

  • As the kit comes, maybe half a kilo. Adding additional springs to the suspension will allow heavier payloads.

  • While I’m at it, do you want bluetooth?

No public wish lists :(