Let's Make Robots!

Several questions about picaxe, servos, servo-controller, connections, and life in general.

Hi everybody, i'm starting to have a lot of questions in my mind about the Picaxe, so i think it's time for me to open a thread :)

But before, just two useful precisions :

  • I'm a beginner. I know it, and i know i have to start simple which is exactly what i'm gonna do, so don't worry if some questions seems too "advanced" for me, i'm actually making plans for future robots, and trying to know what's possible and what's not (although i think that everything's possible!), and what i'll have to get (so i can anticipate how much it's gonna cost, and maybe buy the parts before i actually need them in order to save money on the shipping fee).
  • I have read the Picaxe manuals, and LMR, but the thing is english is not my first language (like many of you as far as i know), and electronics and robotics using some really specific terms, sometimes i'm not sure if i really understood so i may need precisions... or corrections...

 

So let's go for the questions!

  •  If i want a led (or in my case an IR led) to be permanently turned on, do i have to connect it to an output, and launch a "High x" command, or can i plug it directly on the power source (or somewhere on the board) so i don't have to use one of the outputs? I think i can (with a resistor i think), i just need a confirmation.
  • Let's imagine that i have a robot with the board, the picaxe chip and everything. I'd like to add for example an independant circuit, like the one you can see on that beautiful crappy diagram :electronicdiagram.jpgSo this... thing has his own power supply, a led and a switch. Is there a way to activate the switch from the picaxe? Because i have the feeling that when you send a "High" command, it always sends electricity to the output and in this case i don't need current, just to close the circuit. (the truth is, i have an old mp3 player, and i'd like to simulate the fact that i push the buttons to play sounds)
  • How many servos can a Picaxe chip control? Actually i think i know, if i understood well it's 8 maximum for 18x, 28x and 40x. Am i right? So, is there some software or hardware trick to control more servos? I found this "21 Channel Servo controller", but even after reading the datasheet, i'm still not sure about what it is (i told you i was a beginner!). What i think i understood, is that you connect that to your board with its 18x/28x/40x chip, and then you can control 21 more servos (and more precisely). Am i correct? (i hope so, because it's exactly what i'd need!)
  • If i already have a 18x starter pack, with the downloading cable, the cd and everything, if i want to get another picaxe system, what do i have to buy? Just a project board like this and the corresponding chip like this one or this one? (and looks like if i want to use a 40x chip, they don't have a ready-made project board, just this proto-board, do they? So i'd have to add some stuff on it)
  • Where are we going? Why? (that's for the "life in general" part)
Well, that's it for the moment, thanks for your answers or at least for reading... and not getting mad after a n00b and his dumb questions! :D

 

 

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im a hitchhiker
  • Don't apologise for being who you are. Just explain you're new. That'll do. (No more sneering after this.)

  • Jargon can help those who understand it. English jargon is even worse.

  • Permanently lit LED: no problem. Many LEDs work just fine at 5V if you put a 330 Ohm resistor in series.

  • Switching stuff on: the micro controller (Picaxe) can do that. The motor on/off in the "Start Here Bot" does just that. However, you do not want to feed your circuit from the micro controller. It will not have enough power to light an LED or turn a motor. That's why you use an amplifier. Transistors work for most small items like LED's and beepers. For bigger loads, like motors, you need a bigger amplifier. Maybe a special driver chip.

    Learn about current and Ampere. get a multimeter. Measure how much current your mp3 player draws. For playing/pausing playback you don't want to switch power to the player. You want to replace the momentary switch with a programmable switch. A relay could do that. That is like a motorized switch. And that motor would likely need an amplified signal from your Picaxe. So you will need a transistor as well. And while we're on the subject of relays (solenoids), learn about flyback diodes.

  • Many servos: I don't know the maximum. Youre right about the servo controller board. The Picaxe sends a message to that controller and the servo will in turn receive instructions from the controller. Make sure the two boards work together. There exist different kinds of languages for these messages. Definately a question to revisit after your first bot is posted on LMR.

  • Second system: You can buy a new Picaxe chip and plug it into your board. That is the cheapest way to have e "new" system. But you can only use one at the time. You could buy a second Picaxe project board (with chip). Then you don't need to buy an extra download cable. That would give you two systems that could run simultaneously. I don't know anything about the 40x1 or its boards.Someone else here will know.

  • Life: it depends wether you're a hitchhiker or a trekkie; 42 or 47 repectively. 

Thanks, things are starting to be a bit clearer in my head, i'll go to bed a (little bit) less stupid tonight!

And by the way, i found at least one answer here...