I use the picaxe development software from revolution education and I origionally perchased the school experimenters kit from microzed purly because I was 2 lazy to make up a serial cable. Also the school experimenters boards are really cheap and provide good access to the ports with out using previously mentioned veroboard or donut board.

I currently don't use the 18x chips although I think I'll be getting some soon, still I would like this project to stay using the 08M as it's a lot cheaper. As for the 18x Microzed also sells a nice board for them that includes a uln2803 driver chip already installed and nice pads for interfacing again.

Also the 18x allows use of the i2c bus, I last used this bus at TAFE for my micro's assignment and being able to ad heaps of adc's dac's and eeprom's amongst other things could be really useful.

Here is the updated version of the code. (version 3) included now are some delays between fwd and reverse, to stop the motors pulling close to stall current and jamming the relay's. It's now working very well with no issues.

'2 channel robot onoff controller mixed version 3
'by Team NMO
'25-9-2006

'THIS IS AN EXPERIMENTAL CONTROLLER USE AT YOUR OWN RISK


main:
if b11 = 1 then m2:
b13 = 0
b12 = 1
b11 = 1
low 0
low 1
low 2
m2: pulsin 4,1,w0 'fb
pulsin 3,1,w1 'lr
if w0 <= 90 or w0 >= 210 or w1 <= 90 or w1 >= 210 then failsafe
if w0 >= 180 then forwards
if w0 >= 125 and w0 <= 175 then neutral
if w0 <= 120 then reverses
goto main

failsafe:
low 1
low 2
goto main

neutral:
low 1
low 2
goto main


forwards:
if b13 = 0 then fds
pause 500
low 0
b13 = 0
b12 = 1
pause 350
fds: if w1 >= 175 then fl
if w1 <= 125 then fr
if w1 >= 125 and w1 <= 175 then fff
goto main

reverses:
if b12 = 0 then revs
low 1
low 2
pause 500
high 0
b13 = 1
b12 = 0
pause 350
revs: if w1 >= 175 then rl
if w1 <= 125 then rr
if w1 >= 125 and w1 <= 175 then rrr
goto main



fl:
high 1
low 2
goto main

fr:
low 1
high 2
goto main

fff:
high 1
high 2
goto main

rl:
high 1
low 2
goto main

rr:
low 1
high 2
goto main

rrr:
high 1
high 2
goto main

Ok while the relay controller is being beta tested it's time for the next picaxe bot related project.

.......TELEMETRY......

Using a Picaxe 08M which has 3 analouge inputs, a could of LM335 temp sensors and a 433Mhz transmitter module and receiver and a few other bits I'm working on a telemetry system that will send back both motor temp and batt voltage. so Far I've got 2 temp sensors being read by the micro and am having fun atm calibrating them. since the lm335 measures in and I want an answer in Degrees Celcius.

A questuion for people though. What temprature do you think is 2 high for a drill motor. I was reading that more than 50degrees will give you a third dregee burn in a few seconds however I cant work out what temp the drill motors start to smoke at and I really hope someone has these figures as I don't want to find out the hard way.

ive gotten mine to 80 degrees and that seems to be about the death zone for motors the bushings and plastic end bells melting are the problems at the high temperatures. so i always use the metal end bell type with my andrewmods. seems to work well enough
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http://www.youtube.com/user/HyzerGlen - Videoooozzz

It would depend on where you are measuring it and how fast you want it to respond.

Coil Winding Insulation burning would probably be the first failure point in a drill motor, Plastic end-plates melting and moving the bearings around might be another, and the brushes probably start to suffer and desolder the link braid somewhere along the way.

Eventually, you'll probably reach the temperature where the magnets demagnetise (Curie point ?), but by that stage you'll probably be looking for the fire extinguisher.

Problem is, the only direct heat conduction path from the rotor is down the main shaft. Some might make it through the brushes to the end plate I suppose. Putting a temp sensor on the can means the heat has to soak through the magnets after radiating its way across the air gap, which will give it a major delay in response. By the time you were aware of anything untowards going on at the can, it would probably be too late inside.

The heat soak effect will mean that the same temperature your motor will reach after 2 minutes of normal battling would also mean extremely bad things if it was achieved after 30 seconds.

So you would probably want to place your temp sensor in contact with the main shaft (tricky, since its spinning), and perhaps also in contact with one of the terminals (might help you pickup brush temperature).

Determining exact "destruction-in-5-seconds" threshold temperatures isnt necessary or particularly useful anyway.. what are you going to do, stop driving and let them cool down while someone beats on you ?

A more useful monitoring technique would be to plot the "normal" temperature increase curve while you have a good practice push and shove about, then watch for any drastic increases above that curve during battle indicating you're not being nice to the motors.

You probably dont have time to be watching the telemetry displays though (Pit Crew ?), so an alarm if the current time/temp point exceeds the normal time-temp point on the curve by a certain margin would be easier on the driver.

No doubt at this point Jake will weigh in with an accelerometer sensor and and algorithim integrating the normal acceleration curves of your bot and comparing them with the current acceleration curves and letting you know your opponent is overweight because of your reduced maximum acceleration rate.
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