Let's Make Robots!

BRAKE wire on a motor controller

Recenter I got one of this motor controller. The yellow and black wires are for BRAKE as they described. How doe s this BRAKE wires work? Should I connect yellow to one of digital pin and black goes to Ground? anyone knows what's the function of this wire?

I am guess if signal "1" send to yellow the motor stop even throttle is full? and signal "0" to release it? or I am totally wrong here?

Adjustment for potentiometer via Arduino


Hi Guys,

I have bought a joystick as picture above. I tried to connect the potentiometer(the one on stick) to arduino by using following sample code:

What's difference inbetween parking and braking?

I am looking for a dual motor controller board and I found this one:


Something confuse me thou, what's different for PARK & BRAKE? is it like the shift N and P in the car?

One battery for all!? Could that be the problem?

Look at the video. I connect a 11.1V lipo for all the devices include all relays, lights and Arduino. I am not sure if this is a good idea or I should seprate the power source. If so, what's the best setting?? All lights are base on 12V and the motors are 24V and they have their own power source so I am not worry about it. I have use the servos instead just to show the power(PWM?) seems getting low even when I have my control in full speed and Arduino end up reset by itself. After few second it truns back on but slow down again and so on...

Anyone know what did I do wrong?

Ground wire with multiple batteries

Maybe it's stupid to ask this question:

Should I connect all ground wire together with multiple different voltage batteries?

Don't know if this is correct, I never connect batteries ground wire all together when I build such robots. I build a machine with 24V for motors and 12V for other sensors, light etc. Recently I keep hearing about ground wire should connected together in one machine. I am a bit confusing since I don't know much about electronics. Am I hearing the correct information? It won't cause any shortage, sparks or even burned?

32 servo controller / arduino sample code

I wonder if any LMRtians use this servo board before. Got this one long time ago but haven't use it since SSC-32 works pretty good and I thought this board probably works the same way. Unfortunately, it's not. I have connect RX/TX to Arduino but the code doesn't work at all. The manual doesn't provide any sample code for Arduino but someting like:

Is there a device convert webcam USB to A/V adapter??

I know there's something to convert A/V signal to USB like this:


But is there any device convert up sit way from USB to A/V? What I want to do is plug any webcam to TV via A/V cable.

Multiple bend sensors for Arduino

I am trying to build robot control by finger movement so I choose flex band sensor. Anyone has suggestion how to wire it up?

I tried 2 sensors, the A0 sensor works but A1 doesn't. I think the way to wire them up is tricky and confused me. Single sensor was easy, but up to 2 I have no idea how it works.

Here is the code I use:


Anyone using Thing-O-Matic 3D printer in LMR??

Yeah, you can LOL at this crap. This is what I got for first print "20MM cube".

Before I got the whole thing working there are so many detail I have to adjust. It has too many versions on parts and instruction is every where. However, I got it to print out SOMETHING finally.

I2C on Arduino Duemilanove / Mega


It's been while having this strange problem and it seems only myself having this issue. All my Arduinos atmega328 (either offical or mutants) couldn't work with LCD correctly but MEGA works perfectly fine. Recently my project are using WIRE library a lot and they seems not function well. Especially after execute the Wire.endTransmission(); in the line everythign stopped until hit RESET on Arduino.