Let's Make Robots!

Remote Control Can Talk to a Picaxe

Takes servo outputs and sticks them in a Picaxe

I had asked in a forum post if a picaxe could "read" a servo output comming from another source... Thanks to the OddBot, as he nailed it. By the way, O.B. I simply ran the receiver off the same 5V supply I was using for the Picaxe board --No resistor bridge needed, everyone was happy with the same 5 volts. Here is the original post.


In this case I am using a VEX brand transmitter, but understand, really it is exactly the same as a RC car or model airplane transmitter --All outputs from the receiver are for servos.

I was really quite surprised at how easily this is done. I simply connected the data wire and ground from the receiver servo connector to a digital input pin of the picaxe. I skipped the positive wires, all that is needed is the one data wire and for the grounds to be tied together. Also, on the board, I have a 10K pull-down resistor tied to the input. (I don't know if this is needed or not)

Now for the even easier part!!! (The code I used in the video)


pulsin 5,1,w1

pwmout 1,63,w1

low 0

goto main

That's it! --Really. Using the pulsin command simply sticks a number in to the word variable between 0 and 255 in relation to where the stick on the transmitter is. 

So there you go, folks... It works, its simple and if you buy one of those huge controllers with all the extra switches and buttons and the LCD and all, you will just look that much cooler!

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As Chris points out in a completely different thread, for some bizzarre reason, the sticks are attached to pots. Since digital pots which can be controlled by I2C are freely availalble, I figure on replagin the pot with one of these. I'd probably aim for only 6 bit accuracy at first because I'm not too sure how stable the transmitter is with declining battery voltage, but you appear to be thinking the same thing as me...

Chris, this is just about the coolest ever come from you, and in fact it rates the over all top 10 of cool stuff ever in this field!

I never thought about it, it's brilliant!

I do believe that the vision "Autonomous robots wandering about on the streets having their own mind" is nonsense. Humans want tools, extensions of themselves, why would we need independent robots?

However, the best tools are "intelligent" tools. And therefore it is good to make a robot autonomous, because then you have something "intelligent" to control, if you catch me :)

All this comes down to; I think that remote controlling self-thinking robots is the way ahead.

- And thanks to you, it just got a lot easier to make a lot stronger applications; Taking apart say a cheap or even used / broke RC toy, hack in with a Microcontroller with this brilliant invention, and you are go!

Too much cool stuff to make on this site, as Zanthess said :)

Wicked, thanks for inventing & thanks for sharing!


BTW; You would not need a Word variable, when only dealing with values between 0-255, so I should think that the code could be optimized to:


pulsin 5,1,b1

pwmout 1,63,b1

low 0

goto main

 -And then just for the record; Using the pwmout limits you to 2 special outputs, and only these on a Picaxe 28. There will be 1.001 more options - for an example, one could control 8 servos, or 2 motors and 4 servos or set this up on a dedicated servocontroller board and control 21 servos or whatever .. the Pulsin command is the brilliant part here, the rest is optional. I know you know, it's just for the record if anyone saw this and started to make things more complicated than they had to, because they figured that pwmout had to be part of the Chris's invention :)


Everything you see here on this site was built or coded ONLY between the hours of 8:00 and 10:30 PM. -Seriously. The only real chunk of time I have is after I put the boys down and when I go to bed. --Just gotta be efficient, my friend... Well ok, the crystal meth does help a bit... :)


Mate, your quicker than an emu with its tail feathers on fire. How do you find the time to have a family, work and build all these robots? Oh yes and I forgot you also did your bit to save the world.
Well this will come in super handy, awesome reseach there ctc!

That's badass, $0 to build, but I bet that remote and reciever were well over $60 USD :P

But what the hell Chris... you're not Ting-ing anymore at the end of videos.. we can't have that 

Actually, the whole Vex kit retails for about $400. I did a little side job for a homeowner who's husband bought it, never used it and died. -Really. I got the whole kit, including the remote and all the parts I used in this guy for about 2 hours work. This has been a great kit by the way, I am still scrounging parts from the box!


-Sorry about the lack of "ting" in my post... It's this damn cold bringin' me down, man.

You have great timing CtC. I just scored this very same transmitter/receiver (only), new in the box for $30US from AllElectronics.


 They are a great surplus seller for those of us in the US. Unfortunately, international shipping would probably reduce there appeal. I've never had any problems with the several orders I've placed with them. My intention was to do just what you did. You've probably saved me some time and head scratching. Thanks CtC.

I've actually been to that shop a couple times. They have all sorts of goodies, and lots of electronics to play with, like a thrift store of electronics goodness....

Very cool!

A good start to interfacing RF frequencies with the Picaxe.


There are too many good ideas on this site. I think I'm going to have to make a list of things I want to build now.