Need help establishing power requirements!

Hello World!

I’m using a pair of Arduino UNO’s for this project. For power, I’ve been using wall adaptors for both the transmitter and receiver boards. On the receiver side, I’m also using a 2A DC motor driver shield. What’s frustrating me is that this setup will work partially - I can engage / disengage the motors and get them to turn on / off (somewhat - read below). The stepper motor will work just fine, unless I start using the DC motors as well.

What’s going wrong:

I’ve been running into some problems with the unit just dropping radio communications if all 3 motors are in use at the same time. I’m assuming this is a power problem. Also, if I’m running the 2 DC motors (I’ve had a pair of 6V motors on for testing - I can’t get the 12V motors to work with the wall adaptor for power) sometimes they won’t start turning until I give them a little touch. Maybe I’m just doing something wrong with the coding to cause the glitch, but as I’m fairly new to this I was hoping someone could potentially point me in the right direction.

Once the radio communication has stopped, I can’t get it back. The goal of this is to drive a boat with a winch on it, and I’d hate to put all of this time and money into something only to watch it float away.

What I’m trying to get it to do:

  • Use 2 x 12V DC motors to drive the unit forwards / reverse (Banebots RS-540 12V 16800 RPM 39.48 oz-in Brushed DC Motor)
  • Have a 12V unipolar stepper motor act as a winch to raise / lower a weight (12V 0.4A 36oz-in Unipolar stepper motor)
  • Communicate wirelessly via a pair of 2.4 ghz nRF24l01 + PA + LNA

On the transmitter side, I’m using 2 push buttons to engage / disengage the Left and Right DC motor to turn facilitate turning. I’m using 1 ps2 joystick to control both forward / reverse for the DC motors and to raise / lower the weight via the stepper motor via the X and Y values. Additionally, I have a 16x2 LCD screen hooked up to display information to the user.

I’ve read that soldering a capacitor to the nRF24l01 modules can help with power issues, but I still have yet to do this. Could this be the biggest cause of my issues? I tried to do it, but found out I’ll definitely need a stand to do this. First timer problems, I suppose.

This is my first project, and I’m fairly new to coding with Arduino boards (I’m a Chef by trade).

Thank you very much in advance!!

transmitterSketch_final.ino (3.63 KB)

receiverSketch_final.ino (5.25 KB)

You need a much beefier power supply to run those Banebots motors - they pull an amp each with no load!

You should also have a separate power supply for the electronics - motors generate tons of noise on the power supply, and can cause electronics to reset themselves or get into a bad state, so it's often necessary to have separate power supply for the electronics. Connect only the grounds.

My guess is that you are having trouble powering everything. It can only be a guess because you have not said the current capability of your power supply.

http://www.robotshop.com/media/files/pdf/rbban68-banebots-DC-motor-specs.pdf Looks like each of your DC motors has a stall current of 42 AMPS. Since you say the Motor Shield is a a 2 Amp model you will likely fry the shield if either motor gets stuck. They each draw a MINIMUM of 1 Amp with no load.

Thank you both for your quick replies to this - I know everyone is extremely busy and I genuinely appreciate the time and insight you both have offered here.

John, yes I am having issues running everything when all of the motors are engaged. For testing purposes, I was using a pair of 6V motors that came with the boat. When just using 1 motor, there isn't any issues. When both are engaged, it starts to become more unreliable. When I engage the stepper motor with the DC motors running, all heck breaks loose and I lose the connection.

Current Power Supply: I purchased a 30" battleship online from Amazon and wanted to upgrade the boat. It came with those 2 x 6V motors and a battery pack with 6xAA batteries in a plastic pack with a + and - wire coming out from them. I've attached that battery pack to the + and - inputs on the motor driver shield and powering the electronics via the USB cable attached to an iPhone wall adaptor.

It makes sense now that we're talking about it - if the DC motors are drawing 1A each minimum, the stepper motor 0.4 in addition to the nRF24l01 module then no wonder I'm having these issues.

Question: What would you recommend I use for a battery pack for this for the motors? Also, do you think that a 4A Dual DC motor shield would work?

http://www.robotshop.com/ca/en/4a-dual-dc-motor-shield.html