Let's Make Robots!

Arduino Motor Control Code Help

I am currently using a arduino duemilanove, and it is awesome. I have been playing around with it for a couple of days now, and I really like it. Anyways I figured it was time to start to building a robot. I decided to start with the motors. For the motor control I decided to use guibot's tutorial. It worked fine, but the motors only traveled in one direction. Because I wanted the motors to also travel in reverse too I decided to experiment with my own code (on only one motor) that looks something like this:

High Byte, Low Byte, which is which in Arduino

Okay, so I've got a question about how Arduino considers High and Low bytes. By way of example, here's how I thought it worked;

0x00FF == 255, High Byte is 0x00, Low byte is 0xFF
0x0100 == 256, High Byte is 0x01, Low byte is 0x00

Voltage regulator problem

Hi, i recently added a sharp ir sensor, a servo, and a picaxe 8m to my robot, trix. The power supply i made for the picaxe board and sharp ir sensor assembly was simple and should have worked i thought, it was a five volt regulator from parallax, a 9volt bettery clip, and a 3 pin header for the power out (5volt reg, un regulated 9v, ground), However when i plugged the power supply into the picaxe board, my multimeter read only like 2.5 volts across the picaxe and the voltage regulator heat sink got so hot i burt my finger quite a bit.

A Video Game Quintet

Ok ok ok it's not a video about robot. But it says "Videos from around the web you have found and want to share" and well, i just really wanted to share this one with you... i'm sure most of you will like it :D

Radio emitter and receiver query

Hi all..

I'm new here so hello and be gentle!

LMR "mark all as read"?

Is there a way to mark all items as read so that the "Unread posts" page can start fresh?  (Other than actually reading all posts?)


Embedded: "Real men(and women) program in C"

A great link on the use of c in the embedded technology world.

how does XORF work?

howd yu do?

I finaly caught on to the PIC assebly language!

I am using a pic on a simple little robot with the usual bump, revese, turn, obsticle avoidance. it will do more than that later but I havent even writen a PIC program yet so I am starting small. anyway there is on thing I don't understand in the tutorial i read. it is the XORFcommand. I understand xor gates but how does it work here; http://www.pictutorial.net/?page_id=152

it says 

Question about this Transistor!

Well, I was surfing eBay a few days ago.. and came across an exciting deal..100 S9013 NPN transistors for $4 with free shipping..

Of course, before looking into the specifications too much, just scammed over and seen that it can handle up to 30v at 500ma..

But I seen that the "Absolute Maximum Emitter Current"  is -500 ma.


Parallax Board of Education board + extras

This is a collection of items to make up a complete Parallax Board of Education training kit. The Basic stamp is a new BS2P processor which is faster, more memory and comands then the original Basic Stamp2. It retails for $79.99. The board is in mint condition (only used a few times) and tested before listing. Everything else is new except the USB cable I used with my camera a few times. Parallax retail value of over $190, not counting the cable and un-opened bag of electronic parts that go with the book.

problem with IR remote upgrade

i was trying to see if i could make sounds, LDR-test and ir remote test.

upgrade stuff here: http://www.rev-ed.co.uk/docs/axe040.pdf

but there is a syntax error :(



please help!


real time servo & motor control

Hi there

Sorry for this post as I`m sure there are many like this....

I need to be able to control upto around 70 servos and motors from a pc or networked pc`s 

I want to start with one servo and one motor for now.

the thing is tho, I know there is MANY products to set up a sequence of movements on software -> download to controller then run the sequence. or something like that

NiCd discharge question

i have any questions about the topic


when a nicd cell have to be recharged? i am taking about voltage... 1,15v? 1,10v? 1,05v? 1,00v?  per cell

i have a 3xcell batt pack in a bot , the system self recharge when the voltage reach 3,4v, so 1,13v  per cell

is it an insufficient discharge? which can bring to lazy effect?


assuming that X is the ideal voltage per cell  to decide to recharge..... have i to read X  when the battery is under load or when it isunder no load.

Motor Driver question


i'm trying to build 'start here' robot using  arduino as the brain 2 gear motor as the driving force.one of the forumer has point out to me that i need a motor driver to control the motor for forward and reverse movement,

my question is(sorry if sound stupid) do i need 2 motor driver for the 2 gear motor or 1 motor driver is enough.and how to use this motor driver.

thanks for the help.truly preciated



How to use two analogue devices with only one analoque input?

For now it's theory, it's for a future evolution of a future project (yeah i know that's two "future")
Ok actually i'll need 3 analogue inputs (one SRF05 ultrasonic rangefinder and one 2-axis accelerometer), but the 18x picaxe chip has only two. So basically, i need to find a way to share one of the inputs. As i won't need to read the all inputs at the same time, maybe it's doable.

So two ideas came to my mind, each one with its pros and cons.

First idea : a SPDT relay.

With that, two solutions :

Where to find Timing belts and pullies?

    Well for the next iteration of my sumo- "bot" I will need some timing belts and pulleys. The pulleys need a 6mm bore though, I've been searching Google with minimal success, anything I find is either really expensive or needs to be ordered in bulk, can anyone help out?