Possible power issue with Arduino Uno + 2 shields

I'm currently trying to use an Uno with two stackable shields and an Xbox 360 Controller:

So far, I've only been successful in connecting the Xbox 360 controller when the Arduino is connected to the computer via USB for power and the USB shield ontop. But whenever I put the screw shield in between the arduino and the USB shield (still using USB as power), the xbox controller's lights flash once and then remains powered off. I've tried connecting an external power source, both with and without the USB power plugged in, to the arduino using the 2.1mm barrel connector and through the VIN/ground pins, but nothing seems to keep power to the xbox xontroller except for just using the USB to pc as power and only using the USB shield ontop of the arduino.

I need to be able to use the screw shield as I'm planning to use multiple servos linked to the xbox controller. I was hoping if anyone could help me out as I don't know how to read the shield schematics, and was beginning to wonder if the USB shield I purchased only functions while the arduino is powered via USB. I'm almost positive that the xbox controller not lighting up is due to a power problem, but I've only just begun using arduinos so any help would be greatly appreciated!

The USB host shield appears to use SPI. It uses the ICSP connector/pins for the SPI data lines, according to the webpage you posted.

The screw shield does not have the ICSP connector, so the SPI lines are not connected to the USB host when the screw shield is between the USB host and the Arduino.

You could probably fix that by getting a 6 pin (2x3) wirewrap header and drilling holes in the screw shield to get the pins from the Arduino to the USB host shield. Here is that part: http://www.circuitsathome.com/products-page/components/stackable-2x3-header

Thanks a lot for your response, ill try to order that connector and see if it solves it.

Do you think this will solve the issue of having to use the usb as power? I'm making this project for a competition and it'd be really helpful if I didn't have to keep the arduino plugged into a computer in order to work.

You did not mention the Vin power supply. What voltage/current is the power supply? If the voltage is too low (less than 7v) or too high (greater than about 10 volts) you may have a power problem with the 5v regulator on the Arduino. It may not be able to provide enough power to the XBox controller without overheating.

Hey sorry for the late reply, I had to leave home for a family vacation but the external power supply I’m going to be using is a radioshack rc battery 7.2v regulated down to i think around 5v ( it was regulated to a safe voltage for all of our servos/the arduino).

Sorry I forgot to mention, whenever I tried using the external power supply (2.1mm barrel connector and vin pin) without the screw shield+usb for power, the arduino’s lights were on, but the controller doesn’t turn on… it confuses me as to why it only works when the usb is plugged in, or am I still missing something here… :confused:

...the external power supply I'm going to be using is a radioshack rc battery 7.2v regulated down to i think around 5v ( it was regulated to a safe voltage for all of our servos/the arduino).

What power supply are you using for this failed test? What is the voltage on Vin when you power up the Arduino using the barrel connector?

Ahh sorry I should stop saying power supply since it’s confusing, I’m using the battery as the power supply by connecting it to the arduino through wires… I’ve attached a picture of the setup, the regulator section is on the bottom left.

Agh… Unfortunately I need to get another voltmeter, mine isn’t reading any voltages right, even tried measuring brand new batteries… I’ll have to get back to you on that :confused:

Hey so I finally was able to get a voltmeter and the voltage using the barrel connector is about 3.47v (with both the shields stacked). Using the USB for power, it's about 4.44v.

Whenever I plug in the USB for power, the lights on the xbox controller flashes, but whenever I'm using the barrel connector, the lights never flash. Does this mean anything??