Let's Make Robots!

How to get a start in using C and not bootloaders

Hello there lmr, I was thinking that it would be best for me to learn some C and program micros without using a bootloader (happy now krumlink?). I was wondering where to start. I am not trying to bring up a debate but i was wondering if PIC or AVR was better to start off with? Which one is easiest to use and which has the better programming environment. Also what would be needed to start in PIC or AVR? I know a chip, board, and programmer, any thing else? Or any thing else you can think of for someone trying to get into this.

CNC lead screws

Im looking to find some cheap lead screws ( http://en.wikipedia.org/wiki/Leadscrew) online . I was wondering if any one could point me in the right direction to find some cheap lead screws. I would guess that the CNC guys would know where to find them. If any one could give me a suggestion on which lead to use, i would appreciate it. I think i want a lead of about .500" per revelation. This is for my chess robot. I do not want it to be too slow.

Controlling 2 lcds

How would i control 2 16x2 lcds using a arduino mega? I know how to control 1 but i do not understand how to control 2 of them. Edit: i want to control them separately and i would hope i could just use the normal, non serial ones. That is i want to be able to use the liquid crystal library but that from what i can tell only controls one because when you lcd.print you are not saying to which one to print. I understand arduino mega has multiple serial lines so i guess maybe that would make it possible to use multiple serial lcds but i am not sure.

Maze robot coding

As you may know i have built a maze solving robot that does left hand on the wall currently. I have been trying to add the refining part of the code where it figures out the best path to the end without going down the dead ends (i hope you understand what i mean). Well to do that i need a string of chars and a pointer to tell where to store each char which is a turn like 'L' , 'R', 'B' or 'S'. Ok so every time i turn i need to add 1 to the pointer which i call "path_length" meaning the length of the path ie the number of turns the robot has taken.

The most useless machine ever

This is a "most useless machine" i made. I used a instructable but it was a comment by "compukidmike" that was the schematic i used. 

here is compukidmike's schematic picture thing  http://www.instructables.com/files/deriv/FCQ/XPAC/G43EFYKB/FCQXPACG43EFYKB.SMALL.jpg 

Rf links sending and interpreting

I have made a controller and trying to start programming. This is my first time playing around with rf links. I have went through gareth's walkthrough and get messages to print on my screen, thats cool but what about sending other stuff. My question is must i always send messages or can i just send integers? Also i need a bit of help on how to get the receiving code to interpret the message or integer. 
This is my maze solving robot. It uses a Arduino RBBB from wulfden.org. It has 2 30:1 micro gear motors.  The robot has 5 reflectance sensors for sensing the line. … Read more

LCD not quite working

Here is my LCD. http://www.sparkfun.com/commerce/product_info.php?products_id=709. The backlight is working, which isnt much. The problem is that it just isnt displaying the messages. The code is the code in the example and i am very certain it is right. The pins are in the same pins as the code and the example shows. So assuming that this is connected right, i think i may know some of the problem.

Could the 6v i supplied have fried it?

l293d problem

Ok so what does this mean....

 1. the four corner pins are connected to 5v

2. the 2 middle pins on each side of the chip are connect to ground

3. the pins on the outside of the ground pins are connect to the motor

4. the pins on the outside of the motor pins are connected to the inputs.


I have verified those contacts with a multimeter and they are all getting there respective connections and voltages.  

So it is connect correctly.

grrr reflectance sensors



Ok i have these on my chess robot but dont remember what i had to do to get them to work. It is the pololu digital line sensor http://www.pololu.com/catalog/product/959. Im using a arduino and 4 1.2v batteries. Here is my code. Please i forgot how to use these. 



int sensor= 4;

int x;

void setup(){ 

  pinMode (sensor, INPUT);

   digitalWrite(sensor, HIGH);





void loop(){