Hi, I am a new user of Arduino and I am trying to build a vehicle with tamiya motors with the gearbox and the official Arduino motor shield. I got my references from the instructables.com regarding the Arduino robot.
I am trying to start the motors with an external power supply(batteries)
The problem I am facing is that I can't start my 2 motors with 4x 1.5v AA batteries for the Arduino Uno and another 4x 1.5v batteries for the motor shield.
I can resolve it temporarily by connecting the USB cable with the Arduino sketch program on so that the motors can start and then I can unplug it while the motors run on the batteries.
Without opening the Arduino Sketch, the motors will only run with the USB.
The USB can only start a single motor at very low speed while adding both set of 4x 1.5v batteries starts both motors and increases the speed of the motors.
I understand that motors require a large power to start before moving.
I have already set the speed of the motor to max(255).
Is there any ways I can start the motor without using the USB?
Hi tamahome321,
Is this the Tamiya twin motor/gearbox unit you're using? I have used this on a couple of bots and had no problems at all. I mostly build my own PCB's and use various driver chips. I know nothing of the Arduino motor shield or what it uses, does it use it's own library? That could be a problem!
Batteries I use at lest 4 x AA Nimh cells rated at lest 2300mAh, if the shield uses the L293/298 then you will lose 2v plus on the outputs. FET drivers lose almost nothing.
Check your wiring very carefully?? There could be a mistake somewhere, why are you using a demo for the Arduino bot program from Instructables, you DON'T have an Arduino Robot!! The Arduino bot and shield are not! likely to use the same pins for driving the motors, but I could be wrong.
Looking at the code what Arduino pins drive the motors? We need more info, wiring and code, etc to help us help you.
You can see my Tamybots here:www.melsaunders.co.uk under Electronics.
Six volts is not enough for the arduino's regulator you need at least 6.5V Also have you measured what your voltage out of the battries is under load? It also sounds too low once you take into account the voltage drop from the motor shield.
Hi,
Good point Grumpy! I must admit I often use 6 x AA's Nimh cells, but have used 4 x AA's into the Arduino's Vin with good results. But again I've also used a small step-up module to convert this to about 7.5V to drive the arduino, even when the batteries fall below 4v.
I did'ent find the Tamiya motors very efficient and they take quite a bit of current to run, But I think their only rated at 3V, so perhaps over driven.