Let's Make Robots!

Arduino Code Troubleshooting - VEX Transmitter / Receiver

I'm trying to read the signals sent from the VEX transmitter to the VEX receiver through my Arduino Mega. I started with this code and then made some modifications to visualize the outputs.

LCD pin names

We have this LCD and we are trying to connect it to the Arduino. We are having problems with the pin names. Here's what we have so far:

Vss - ground

Vcc - voltage (+)

VLc / Vee - we believe this one is for contrast - confirmed

RS : register select

R/W :read / write


D0-D7 : data pins

VB+ : LED positive

VB- : LED negative


Problem with Arduino and SN754410 circuit

I arranged this circuit to prevent wires from crossing each other... I'm using using paperclips to make the circuit =). This is what I have so far: 


I tested the circuit and it works! Just one problem: during the "void setup()"part of my code (Arduino), the motor starts to run without any input. I tried to set the PWM pin low, but it didn't worked. How could I fix this? Pull-down resistors? Here's the code I'm using:

Where to put clamp diodes in a SN754410 motor controller circuit?

After a quick Google search, I couldn't find a schematic for the SN754410 with the clamping diodes. Instead I found this document which uses the L293. Could I use it to build the motor controller with the SN754410? What changes would I need to do to use one motor per IC to double the max continuous current? I have some 1N4006 diodes, could I use them in this circuit?




LCD - V.Smile Pocket

Would it be possible to make this thing work with a microcontroller? It is from a V.Smile Pocket (handheld brainwash learning station). The V-Tec site says it's a "full-color LCD screen with 320 x 240 resolution". That's all I have.

The white cable is what connects it to the main circuit. It has like 25 metal points/pins. 

[My cell phone camera is not so good]...



How to connect SPDT relays to control a motor's direction?

I have two SPDT relays, but I don't have much info about them: [a: side label] & [b: top label]

a) 8A - 250VAC

    10A - 28VDC

    DC - 5V

b) Coil: DC 6 9 12 24V

    Capacity: 5 8 10 15A 250VAC

I also have some transistors like this one, some old circuits with various types of resistors, and some diodes too.

How should I connect these things to make a motor change its direction?

What now? Struggling with motor controllers.

Since my Arduino motor shield died for unknown reasons and the Mr. Basic controller still wasn't working, I was officially stuck. I posted a question in the forums, and Simon Z pointed to Polulu and gave me some extra info on controllers. After looking at Polulu's catalog, I saw that most of them were out of my budget and making a controller is out of the question because there are NO suppliers in my country. So now I'm stuck, again. I could buy parts on the internet, but the shipping is always a problem. For exaple, I was looking at the L298 motor controller from Solarbotics.

robot break dancer

simple robot dacing

motor shield not working...

I was testing a geared stepper with my arduino motor shield and it suddenly stopped working. It has power in the 5V pin 'cause that's were I have my Ping sensor connected, but there seems to be none going to the motor connections. Any ideas? I can't afford another one... please tell me it's not dead.

PS: The L293DNE was a bit hot yesterday while testing other steppers, but it was working this morning. 

90 degree shaft

I would like to know how to change the direction of a shaft by 90 degrees (I want the output shafts of Mr. Basic to be 90 degrees down without moving the motors). Any suggestions/ideas ? (please focus more on how to mount the 'system' to the shafts). Thanks.

 PS: I know I could easily do that with two special gears, but I don't have and/or know where to buy them. Would it be possible to modify normal gears to fit this purpose? If so, how?