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Dear all,

This is my first time on the arduino forum, i've searched before asking this question.

I'm a doctor, and also a software programmer in the field of physiological modelling (i.e. creating models which attempt to predict the behaviour of the human body).  I also create software which improves medical simulation fidelity.  I'm experienced in Java and other OOPs but have limited knowledge of USB ports etc.

I've just been given an android tablet (asus iconia tab A500) which runs honeycomb.  The tablet has a hosted usb port.  I can see a few posts about combining android phones with arduino boards, and this would be very exciting for me as I would like to create a prototype medical device.  The arduino board would need to have the following output and inputs:

1) Three analogue outputs which would range from 0 - 3mV.
2) Two analogue inputs which would range from 0-20mV.

The medical monitor which reads the outputs i'm guessing would have a sampling frequency of at least 30ish Hz, so I think I would need to be able to update the outputs more often than that.

Ultimately I would like to have in the order of ten analogue outputs.

Is this possible within an Ardunio + android tablet enviroment?  The reason I don't want to port the entire project over to C# (or whatever most arduino projects are written in) is that we also intend to release education material onto the android market and duplicating the code base makes me sick in my mouth a little.

I see this product advertised:
http://www.seeedstudio.com/depot/seeeduino-adk-main-board-p-846.html?cPath=132_133&zenid=e4c29443713d97e81054a86ec21fc20c
would this be a good idea or is there something else?

with thanks for your help

kenneth
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What you describe is theoretically possible but the small voltages (0-3mV, 0-20mV) imply very careful attention to getting the signals on and off the system. It is not going to be just a simple matter of hooking them up to the analog to digital converters as those kinds of signals will easily get lost in the noise being generated by all the electronics.

Ideally you would put the small-voltage stuff as close to where they are needed as possible and communicate digitally to the Arduino/Android combination. In any case some extra hardware will be necessary to work with these analog voltages.

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couldn't I just make the voltages 0-2.5 volts then (or whatever) and put a resistor in between the board output and the monitor?  Are you saying that analog voltages need extra hardware, or and an android tablet and arduino need extra hardware?

k.
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In theory, yes, you can change between high and low voltages simply with resistors but down in the 2mV range you are going to struggle with noise. The resistor solution is not going to properly attend to keeping the integrity of the signals from one place to another, i.e., noise immunity. In an "open" hardware environment like an Arduino board you will easily have several 10's of millivolts of noise picked up by wires, swamping the signals that you are trying to communicate.

I believe you will need extra hardware above and beyond the tablet and Arduino to properly condition the low-level analog signals, as well needing to pay careful attention to the overall system design such as the cabling to/from the sensors.

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could you point me in the direction of where I could read up on this hardware?
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Let's start with the analog inputs -- a good input stage for low-level voltage signals is an instrumentation amplifier:

http://en.wikipedia.org/wiki/Instrumentation_amplifier

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