Let's Make Robots!

Calculon's Arduino Serial madness, part 2

Hello LMR,

Calculon has been tinkering with his Arduino for a few months now and he likes it. He is at the point where he is trying to get his 'duino to communicate with another device. His question is: HOW?!?!?

More specifically:

1. Does he use the Serial.print command? Serial.write?

2. How does he send more than one byte at a tyme?

3. Here's an example of the required byte sequence:

     in hex: 0x8D, 0x7F
     in decimal: 141, 127

Does he just send one byte, and then another? 

motors and amps

hay, during building first robot i had some difficulties with my power source , my setup was basicaly a start here robot but with arduino  i used the l239d motor driver , my power supply was a ni-mh 9v rechargeable battery powering arduino, and 3 AA battery pack to the motor driver


my problem was my motors runing weakly, or slowly ( they are gm8 solarbotics motors ), this did inprove slightly when i switched to the battery source mentioned above .


How to use solar panel?

I bought this the other day -  http://www.radioshack.com/product/index.jsp?productId=2062564 to use for a beam bot. Problem is, it was very cryptic with the intructions, so I'm not sure where to solder to for + or -.

If anybody has any experience with this, I'd love to hear your thoughts.



anybody tell the differance between phototransistor and a photodarlington

wheels and motors

Hi all I have been trying to gear my motors down which is a real pain so I was thinking of buying a Tamiya 70097 Twin-Motor Gearbox. Does anyone recommend this or a different type. I wanna keep costs down so something nice and cheap that has 2 geared independent motors. Also I didn’t think it would be that hard to find wheels.

Anyone with a CNC mill taking paying/exchange jobs?

I'm looking around to see if anyone's got a 3-axis CNC mill they'd concider doing a job on? I'm trying to address the lack of parts for making the current RepRap "Mendel".

 I've been using silicone moulds and PU fast-casts for a couple of years, so if I can get someone to make a single version of each part on a mill (without undercuts/crossways holes) I can make multi-part moulds to cast replicas.

how-to LMR meet-up

Inspired by the 2 years anniversary text on the LMR front page, I got to wondering

What do we require to make a successful LMR meet-up in real life?  

Yes I know we're spread all over the world, and anything higher than a 2% show-up rate would be a unbelievable. But what kind of physical preparations would one need? A large conference room with enough electrical outlets, loads of tables, PA-system and presentation equipment, and short distance to a bar and a cheap-ish hotel.

What else?

Robots Community and Tutorials www.botstop.net

Hello every at Lets Make Robots, Happy Birthday.

I would like to make you aware of a website I am starting up, BotStop.NET. You can upload your robot to have it reviewed by others in the robotics community, read and make suggestions towards robotics tutorials, take part in competitions to win parts and components for your creations, or chat in the forums.

LMR birthday

LMR birthday video from Dagu with surprise ending :P

fritsldr with arduino

hi guys.
ive been having some problem figuring out the code for a fritsldr in arduino.
so far i keep getting this error:

error: expected unqualified-id before numeric constant.:

 error: expected unqualified-id before numeric constant in function 'void loop()'

PICAXE editor

I put this into the PICAXE programming editor

servo 0,150
wait 2
servo 0,225
wait 1
goto main

then I hit F5. A window comes up, downloads the program, and says "Download was successful! Firmware version A.6, Memory used = 18 bytes out of 4096." But nothing happens. I unhooked the sero and when I hooked it back in, it slightly jerked. I did this about 4 times until it stopped doing it. Now nothing happens. Is this something wrong with the electronics? 

qrd1114&qrb1114 phototransistors

trying to build line follower anybody tell me if the 2 sensors can be interchanged trying with the qrb and having trouble getting the motor to shut off ir will emitt and motor will run. will buyqrd if have to but will like to use ones i have

   thanks for any help


Mega cheap breadboard


$4 for a 400 contact breadboard. I just ordered one so I'll let you know how it is when I get it. 

I got some trouble over the first project.

Hello I am trying to do the first project of the robots, http://letsmakerobots.com/start I bought all the things needed but I got some trouble I dont know how to connect the sensor, its exacly the same as the project uses. I am getting lost at the part that says that because he refers to some other kind of sensor and than there is no image to understand how.


anybody got any qrd1114 sensors they want to get rid of i need 2 but will take more .need them fast

Just bought a dual PC board... I feel dumb.

Hey guys.

I just got home from the rat shack with a few of these babies.


Nobody in my town has breadboards, so these have to do until I get one from the net. Anyway, I'm pretty sure I get the idea of how to use one, but I'm hoping to find a short tutorial on the basics of using it. I know they're cheap, so I can screw one up and it's a non-issue, but I'd like to avoid that if possible :)

Spielwarenmesse International Toy Fair

 As mentioned in my new blog, Jack and I will be attending the Spielwarenmesse International Toy Fair next week. We will fly to Nuremberg, Germany on Tuesday (2nd) and will be there till the 9th. Our stand is No. H6 / A-32.

If anyone wants to visit us but doesn't want to enter the fair then we will be staying here: http://www.hotel-aurora.info/



High signal from pic to pic w/(2) pwr supplies?

So here we go:

Walter has (2) 7.2v  packs, one for data and one for servos. Each has a switch and can be turned on idependantly (manually). During the "start-up" routine, I need the main picaxe to know if and when the servos have been turned on. It would be like this:

I turn on the main brain. The LCD turns on and displays a message to tell you to "turn the servos on, please" --I need the main brain to know when you have turned them on. 


Hye, Sorry to bother you, I have some questions about a hexapod. I want to make the same like this http://webx.dk/robot-crawler/robot-crawler.htm  for my college project, if you have time to have a look on it, I want to know the configuration of the pcb board, an electrical schematics electric parts needed, what cpu usses, what kind of servos (can I use weaker servos?) . If you can help me, I would be very pleased, if can't..no problem. Have a good day.