Let's Make Robots!

Mr. General

  • Component category:
Mr._General_4.bas16.45 KB
Tone.zip9.68 KB
Mr__General_ATmega8_Edge_Detect.zip3.23 KB
Mr__General_ATmega8_Object_Detect.zip3.25 KB
Mr_General_Nano.zip3.21 KB
Vendor's Description: 

Video: http://www.youtube.com/watch?v=7Ve318yVUdU

DAGU products support site: https://sites.google.com/site/daguproducts/

This kit has recently been upgraded to include a USB interface, programming cable and the ATmega8A processor with the Arduino bootloader. The Manual has been updated with wiring instructions and diagram as well as USB driver instructions and trouble shooting section.

An improved "Tone" library is included on the CD as well as being available here that allows the Tone command to function on the ATmega8 processors (thanks to Robot Freak and Brett Hagman).

Based on Bot 08M, Mr. General is designed around a breadboard and includes the universal sensor brackets designed here at LMR as well as my IR object tracker in the form of a compound eye.

The Picaxe code was written for the picaxe 28X1 processor. The first Arduino code was written for an Arduino Nano which has 8 analog inputs. The second Arduino code is for an Arduino with only 6 analog inputs. This version uses digital inputs for the corner sensors which gives them slightly less range.

An IR LED and phototransistor is mounted on each corner and can be used for edge detection or object detection depending on how you choose to mount them. When mounted for object detection they can also be used for swarm communication. These sensors have an analog output but can also be used with digital inputs.

Here are some videos using a picaxe 28X1 and here is a video from GuangZhou University using the compound eye and an arduino to solve a maze.

The compound eye allows your robot to track a moving object but can also be used for IR communication between two robots. Other range sensors could also be fitted to the sensor bracket.

2 factory modified, continuous rotation servos allow speed and direction of each wheel to be controlled by a single digital output.

The kit does not include a micro-controller as the breadboard allows a wide variety of processors to be used. A generous 140 piece cable pack allows easy connection between the breadboard and sensors.

2 individual voltage busses allow for up to 3 different voltages plus ground to be used. Ideal for 3.3V devices and op-amps. A basic recharge circuit allows NiMh or NiCd batteries to be charged from a 9V DC source without being removed from the robot.

All spare room on the main PCB is configured as prototype board as show in the picture below. This allows additional sensors and circuitry such as voltage regulators to be easily added.


Of course being designed with parts from LMR it is only fitting that we have the LMR logo on the box.

 Click on the photo for a bigger picture.





More information can be found here: http://letsmakerobots.com/node/24348



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How much does it cost?!?!?!?!?!


I bought this lovely Mr. General and I'm now working on it for the last days. And as I'm more a programmer than an electronics freak, I can say for now: A great starting point for my first robot experiments and I hope a good platform for my big plans ;-)

Building itself was no problem. Some things could be clearer in the manual, but with some thinking finally everything worked fine.

At the moment I'm trying to connect it to my seeeduino mega (an arduino mega clone) and can't await to start programming, adding more sensors, features etc. I took this processor because I'm allready experienced in programming it.

And there comes my question: The seeeduino mega board itself works great (lots of pins!!!) but the voltage provided by Mr. General is too low, so it doesn't work properly (for example my lcd display doesn't work at all). Do you, OddBot, or somebody else have any hint for me, what I can do? I read OddBot's text on regulating voltage and I think there might be a solution in it - but maybe there is an easier way?

Here an Idea that I had myself: My processorboard needs at least 6 volts, at least 7 V are recommended by the manufacturer (max 12v). The servos need max 6v, the sensors 5v (Is this maximum for the LEDs?). So I could take a 6v rechargable Battery and power the servos directly and the sensors from the 5v output of the processorboard, but 6v maybe still too low. So can I take more than 6v and how can I connect this to the servos? For now there are 4 inside mr. General, but I'm planning to add some more ...

Thanks to OddBot for inventing Mr. General!




I am glad you like Mr. General. Please email me and tell me which parts of the manual could be clearer. I would be happy to improve it. So far it has only been tested here by a new employee and she made several improvements.

As for the voltage problem, Mr. general was designed to have the processor (e.g. atmega168) plug directly into the breadboard as the chip will run happily at 4.8V or to have a 3.3V regulator built onto the PCB or breadboard for 3.3V devices.  Arduino boards tend to have their own regulator which is why they need a higher voltage.

Connect an additional 2x AA battery holder with it's negative lead plugged into Mr.General's Vcc and the positive lead to your boards +V input. Connect your boards Gnd to Mr. Generals Gnd.

This will give your boards onboard regulator +7.2V while leaving Mr. Generals sensors and servos running at 4.8V. The only disadvantage is that the recharge circuit will only charge the batteries in the original  battery holders.


Thanks for the fast response, Oddbot!

This is really an easy option adding two further batteries.

Do I see this right, that the two additional batteries will discharge different (much slower) than the other 4? Is it alternatively possible to add one 9v battery instead of the 2 and power the arduino directly from it? for me this seems clearer dividing the circuits than mixing up the batteries, but maybe there are major disadvantages in this, which I don't see ...

Another Question concerns the recharching possibilities of Mr. General (which is a great feature, not to forget!): How does it work? which recharchable batteries are recommended? what about recharging time? what happens if I recharge too long? will my beloved Mr General get burning? And has the yellow LED on the PCB something to do with the recharging feature? (unfortunatedly nothing about this is written in the manual, I'm setting up a list of things for you, which were unclear for me ... coming soon)



Yes the extra 2 batteries will discharge slower because they are only feeding the processor board. Yes you can use a 9V battery instead as long as the ground of the 9V battery is connected to Mr. General's ground.

The recharge circuit is only a simple trickle charge circuit. Unfortunately the engineer resposible for the board design forgot to put 9V DC and a few other things on the first batch of PCB's. The schematic in the manual should be fairly self explanitory.

Mr. General is designed to work from 4x AA NiMh or NiCd batteries. With a 9V DC plug pack connected to the charging socket and the switch in the off/charge position the yellow LED will light up to indicate charging. This is just a simple trickle charge circuit that will charge the batteries at aprox. 100mA. 2400mAH batteries would need about 28Hrs to completly charge from dead flat.

The charge feature is really designed to allow the batteries to be topped up overnight. Because this robot is designed for students I have kept the design simple, not just to keep the cost down but so that the students have plenty of oppertunity to improve it. There is enough room on the PCB for students to add a purpose built recharging IC as well as voltage regulators etc.

This robot was designed to be hacked!

I have attached version 4 of the software. This allows the robot to become bored if an object does not keep moving enough. When the robot gets bored it backs away, looks about and goes in the direction with the most room using the eye as an uncalibrated range finder. This version has improved edge detection and smoother tracking.

The code is fully documented with rem statements explaining every line of code to assist in modification / translation.

What are the dimensions of it and of the wheels?
Great value for money!
I have updated the component with dimensions.

be able to get it cheaper minus the IR Eye? No offense, but I don't really need one right now.

What I do need is 3 bots like this...