Let's Make Robots!


This afternoon got off to an auspicious start.  The problems I was having loading AXEpad onto my Mac seemed to have had disappeared since Thursday.  An hour later, I had the USB successfully loaded.  (For Mac users wondering how this is done, make sure you read the USB Setup section of the Picaxe manual.  One thing the manual neglects to tell you is that you have to also download a piece of software called a serial driver, which you can get for free from FTDI.com or from Rev-Ed's website.  Once you have all the software properly downloaded you have to then activate the USB port in the Network Settings section of your System Preferences folder.  Hint: got to "Network Port Configurations" on the drop-down bar just above where it lists the status of your internet connection.)

After getting the software all hooked up, it was time to start programming.  

 Except it wasn't.  Because apparently the robot Gods hate me.

I plugged in this basic command:

servo 0, 150 

..and nothing happened.

I tried 

servo 0, 200

...and nothing happened.

But I can't for the life of me figure out why.  Everything seems to be in order.

The software seems to be working fine.  After I enter a piece of code, it loads for a few seconds.  Then I get a screen saying that the command has successfully been sent.  So I don't see any problem with that.

After reading some of the forums here, I thought maybe I had gotten one of the A.4 "glitchy" versions, but when I went to check I saw that in fact I have an A.5 one.  So that theory's dead.

P3080036.jpgThen I went to the manual and figured out how to run a system test.  In the picture to the left you can see that I've attached an LED to output 4, and also inserted another 330 resistor.  After connecting the LED, I gave this command:

main:high 4 

pause 1000 

low 4 

pause 1000 

goto main

 Again, nothing.  Not even a flicker.

I've spent hours and hours looking on this and the PICAXE forum to see if I can locate a solution to this problem.  But I just have no idea what's going on.  It seems unlikely that this has anything to do with bad parts.  I am certain that I am doing something wrong, but I just have no idea what it is.

Everything appears to be hooked up properly.  The software is all installed correctly.  The soldering job isn't pro or anything, but at least for the extra pin on the servo 0 row, it isn't fatally bad. 


I'm just really confused and really frustrated.  I don't really even know what to try next.  I suppose I can solder a pin to the 7 row, and try the servo there.  But otherwise, I'm at my wit's end.


Here's to hoping tomorrow is a better day. 



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"Lizzen carefully, for I shall zay zis onely onze!"

Is that third band on your resistor(s) yellow or brown? The colour of the photo makes it difficult to tell. Brown is the colour you need by the way. 

On the bright side: you did not smoke anything!

You have your LED wired to + and Signal. Try signal and ground and flip your LED around. In terms of servo commands, sometimes they like a pause after the servo command is sent. Try this:


for b1 = 75 to 225 step 1

servo 0,b1

pause 100 'make this smaller to make the servo go faster

next b1

for b1 =225 to 75 step -1

servo 0,b1

pause 100 'make this smaller to make the servo go faster

next b1

goto main


Right on with LED Chris.  Thanks.  The LED I'm using was pulled from one of those key-chain lights.  The cathode is actually the longer lead, and the anode the shorter.  I think that's what messed me up.  Anyhow, after I switched around the ground wire to connect to the cathode, it responded to the LED command.  Which is great news.

 As for the servo, well, I don't know.  The resistors are on correctly as far as I can tell.  You may be right Rik, but the guy at the electronics store assured me I had the 330's.

I'm gonna take everything apart and solder a pin to 7 and see if I can hook up the servo there. 

Orange, Orange, Brown... (Forget about the last stripe)

Well, connecting the servo to row 7 was a resounding FAIL.

I guess I'll have to go get some different resistors and hope that's the issue.  As of now my resistors go orange, orange, yellow.  So that may very well be the culprit.

Thanks for your help guys. 

Resistor color codes for future reference. The third strip is a multiplier for the first 2 strip digits. Orange orange yellow would be 330K (330,000 ohms) not 330 ohms, so nearly none of the signal was getting to the servo, most dropped through the resistor.

Once you figure out the problem, you'll be stoked, and it will never happen again. Some suggestions:

- Where did you get the servos? They may be rated for a higher current than your axe is pushing. You can buy a 10 pack of the right kind at Radio Shack for a buck or two. 1/4 or 1/8 Watt. Orange Orange Brown.

- Have you tried the servopos command? As far as I can tell, they do the same thing (check the manual for the difference).

- Search this site for some info on changing your axe's frequency to fix servo problems. It's here somewhere. I've never needed it myself but others stand by it.

- what kind of servo is it?

Argh.  I feel like such an idiot.  I knew it had to be a simple mistake on my part.  Oh well, this is how one learns, I suppose.

And thanks, ya'll.  I'll report back once I get the correctly colored resistors.