Help using a L9110 motor driver IC

Hi, I have a pair of L9110 Motor driver IC's. I seem to be having problems getting both motors to move at the same time. One motor works fine but when I connect the other one the Arduino resets. I am sending both motors logic high and low as stated in the data sheet but still the Arduino resets with both running. It looks from the data sheet I need some sort of square wave but I am not sure.

see my schematic here http://www.isb.bj.edu.cn/class/ues/images/l9110.jpg

also here is a data sheet but I am sorry it is in Chinese. http://www.bricobot.ch/specs/L9110.jpg

Please, any help would be welcome.

Thanks,

Randy

What is the current draw for the motors? If you are powering this driver and motors from the Arduino's +5vdc source then you may be drawing too much current causing the Arduino's on board voltage regulator to protect itself by shutting down monentarily and causing a reset to the Arduino processor chip.

Lefty

Does it reset as soon as you start the motors, or after you load them down?

There are a couple of concerns here. First, if you are driving both motors off of the 5V Vcc, you need to make sure your power supply or voltage regulator can handle the current. Otherwise, the regulator could goes into an over-current protection mode and shut down. This would reset your motors. In this case, the AVR would also reset if you applied a heavy load or completely stalled the one motor while it was running.

Also, on your schematic I don't see ANY capacitors. That can be a significant problem. There should always be a 100 nF cap between Vcc and ground close to the AVR to protect against high frequency spikes. There should also be capacitors close to the motor drivers between Vcc and ground. The value of these capacitors depends on the current draw of the motors, but I like using 120 uF caps as a safe bet. These caps provide a 'local battery' effect providing current when the motors switch on, so that the voltage of Vcc doesn't drop too low. Without them, switching the motors on and off will cause voltage spikes on Vcc that will likely cause the AVR to reset.

Hi Lefty,

I checked the current draw of the motors and it was some where between .05 and .2 amps. I am powering the motors from the same 5V in a 4 x 1.2 battery array

BTW I am using a homemade Arduino not a regular Arduino. So there is no voltage regulator attached.

Hi Soundguy66,

Shutdown start as soon as I start the motors. I can get one going but then I connect the other motor everything shuts down. I think I am under the current draw with .05 to .2 amps. Yes I do have caps near the Atmega 104's across the output lines to the motors.

Thanks for your help

In the data sheet it shows a square wave can someone tell me about that?

Thanks

It's a de-coupling problem, read:- http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Thank you very much I will read it.

It turns out to be a PWM issue. The chips want PWM input. So now I just need to find out how Arduinos can do that.