Let's Make Robots!

SPI problem

Hello guys. I'm trying to make an spi connection between the arduino and an IC. Actually it's not an arduino, it's an atmega328 on a breadboard, but i'm programming it with the arduino IDE through ICSP. I've got a problem, this sketch doesn't work:

void setup(){

byte clr; SPCR=B01010011;



digitalWrite(10, LOW);  //10 is basically the SLAVE SELECT pin   

spi_transfer(B00000100); //powerup delay(10);

digitalWrite(10, HIGH);  

digitalWrite(10, LOW);

spi_transfer(B00000000);  //setrec

Help with Sabertooth 2x25

Hey everyone. I am building a couple of projects using electric wheel chair motors. I am using the Dimension Engineering Sabertooth 2x25 motor controller. The proble I have is I am sending pulses of 1000, 1500, & 2000 us to the sabertooth and am getting random results (both forward, one forward the other reverse, both fast, both slow, one fast & one slow, etc) with no apparent consistency.


What does this code mean?

I see this about everywhere in PICAXE codes.

b1= %00110000

what does the percent and all the numbers mean?

Urgent PICAXE questions

Does the PICAXE-14M have analog inputs. I see ADC on it. I'm ordering this like right now so I need an answer.

Problem with hexapod

Hi, I'm new here and I'm not so used to forums so if I'll make mistakes posting, writing etc please forgive me and help me to find the way! :)

I also have to say that I'm not English so forgive me for my English or if I can't get something!

So... Let's talk about my problem..

Infrared Proximity Sensor

I have a Infrared Proximity Sensor. Is there a way to debug the distance so I know how far I want it to detect something. I always see people's codes have 400 and 700 and I'm like where did they get those?

Concept Question

Now that i have several small robots under my belt, along with a somewhat firm grasp of programming basics i would really like to scale up. I worked on a robot for the FIRST robotics competition which was really my first time handling a somewhat larger project. The materials required for that robot were quite expensive and the robot itself is too big for one person alone.


I'm just going to throw some ideas out there 1. to force myself to actually get started on this and 2. to hear some constructive feedback and to make sure i'm being reasonable.


LCD03 and PICAXE 28 pin Project Board


Does anyone know how to connect a LCD03 to a picaxe 28x project board?

EDIT: I've already connected the LCD successfully to the board :D.



I've been building my first robot, and have been looking for a way to make it more power efficient.

When hooked up to a power supply lower than 12V 8AA, the Arduino's power LED turns dim at every once and awhile, and the servos turn on and off continually, when they're not supposed to.  It works fine with 8AA.

I also measure the input current.  It was about 1A, which seems like way too much.

I've looked at the robots here on LMR and their are some that can power twice as much as I have hooked up to my arduino when connected to 4AA

Are my motors borked?

A couple weeks ago I posted about my Rebound RC car which I'm trying to make into a robot.  I had trouble getting the motors running at the same speed.  It was suggested that my H-bridge was bad, so now I've gotten a new one and am still having trouble.

Using SRF005 with arduino

Can anyone please show me how to program my arduino duemilanove  to use the SRF005 ultrasound? 

thanks in advance : )





What's the best way of turning? We have 2 DC motors, one on each wheel. To turn right I was sending forward command to the left motor and backward to the right motor but I'm having diffculty to keep track. The min PWM to give first spin changes drastically in every situtaion.  We have a digital compass and and I'm thinking relying only to that for this decision but it would be better if I had a look up table with tick numbers of encoders for each desired degree.


 How do you do turns in general?


"How to make your First Robot" Questions

Dear LMR community,

If you are unaware of the "How to make your first Robot" documentation by fritsl, then look here first:http://letsmakerobots.com/files/lmr-Start.pdf.

Ok, now with my questions:

First, and formost, what in the world is wrong with the page numbers, for instance, what should be page 8, has an upside down Y for the page number??

Second, could this also easily be made into a line following, object avoiding robot? Any ideas how?

Homebrew Servo Controller Issues


I've been developing my own serial servo controller for the hexapod I'm working on, using a Microchip PIC16F74.  It accepts serial input and controls up to 20 servos. The servos are connected in ports A, B and D.  Power for the PIC is from a 9v battery via a 7805 regulator.  The servos have a separate power supply from a 6v battery pack.

Anybody know anything about building amps?

I've recently come across some fairly nice sized speakers that I'd like to hook to my TV.

But, I thought it would be cool to build an amp for them myself. They're unpowered, which means there needs to be some sort of go-between from my TV to the speakers to give them enough power.

I've done a little googling, but the most I am coming across is little altoids amps for headphones - which isn't what I'm after.

My thought is though that I might be able to take one of those schematics and upgrade the parts to a higher voltage... I'm not sure really.

Getting data from remote Arduino.

Hi, I've one Arduino Duemilanove board connected with Xbee Shield and want to send data of Signal "H" and "L" for every 3 seconds to my PC. I've another Xbee on Xbee Adapter Kit connected to the PC. My aim is to transfer the data from the remote Arduino to the PC but I can't get it right. Neither the "Terminal" of X-CTU nor the "Serial Monitor" of arduino software show the signal from my remote Arduino.

My step for setting up the connection is as follow. Please help to correct me if I have done something wrong or left something:

project with sensors but without pic and plc...

hey i'm looking for a project with sensors but without pic and plc. can anyone help me? it's my mechatronic engineering 2. class term project. i'm thinking to make http://letsmakerobots.com/node/2679 but it's very simple and very easy. how can i improve it?

Parallax Propeller

Does any one use Parallax Propeller on here?? If so, what are the pros and cons?

windscreen wiper motor problem


I am building a tank style robot which uses two windsreen wipers (one to run each track).

My problem is that when i try to put both motors running in the same direction( i.e one positively biased and the other negatively biased as they are faced in the opposite directions) the battery is shorted as the housings of these motors are grounded.

Those anyone know of a solution to this problem? or is there another kind of  windscreen wiper motor that does not have the housing gounded?