Question: How do I run the Arduino Uno and Ardumoto logic from one battery and two motors from another battery?
What's working now: Currently have Ardumoto shield stacked onto Arduino Uno. Two small DC motor gearboxes are wired to the blue screw terminals on the Ardumoto. (The motors/gearboxes were salvaged from a robot education toy designed to run on 2xAA's.) One 9V battery is supplying power to the 2.1mm barrel plug on the Arduino. The Arduino, Ardumoto shield, and attached motors are all drawing their power from the one 9V battery. Basic test program uploaded to drive forward and backward works fine. This is a proof of concept and learning setup as I prepare to build a mini sumo bot.
What I think I want to do: Add a blue screw terminal on the Ardumoto next to "VIN: Max 18V". Connect a separate battery to this terminal which will be used to drive motors only. For this practice project, will likely connect either 4xAA's or a 9V battery. Eventually, I'd like to connect a LiPo 7.4V 800mAh battery to run some more powerful motors. (The LiPo's are 'free' from my R/C helicopter.) It's my understanding that separating the motor's power source from the logic chips' power source will be safer.
Hello,
Soldering in a screw terminal is the way to go. The L298 accepts a power source on Pin 8(?), specifically to drive the motors. Either battery should work, just check your motors specs for their max load/stall current. The L298 can only deliver .6A with 1.2A spikes. If your motor repeatedly stalls you may fry your L298.
The L298 accepts a power source on Pin 8(?), specifically to drive the motors.
Thanks for taking time to respond!
To clarify, can someone confirm that I should be able to do the following without damaging the Uno or the Ardumoto...
Solder blue screw terminal to the Ardumoto next to "Vin..." at the edge of the board near the other blue terminals.
Attach a new 9V battery to the new Vin terminal that the Ardumoto will automatically use to drive the motors.
Keep the existing 9V battery attached to the barrel plug on the Uno board.
Intermittently connect the USB cable to upload program changes.
And that I do NOT need to...
Clip off or bend out any of the pins that connect (piggyback) the Ardumoto shield to the Arduino Uno.
Solder any extra capacitors between any components
I've seen some other Ardumoto posts that describe what sound like pretty convoluted steps. Suggestions so significant that surely they would have been mentioned in the getting started tutorials, etc...
Thanks in advance for any further tips! I don't mind experimenting and learning slowly, but I don't want to cook my new toys either!
There's one further thing you need to do. Currently, you must have a connection somewhere between the Vin supply on the Ardumoto board and either +5v or +9v. You will need to remove that connection when you connect a separate supply to Vin.
