[hackspacebristol] Need to extend ADC on Arduino

Matt Hamilton matth at netsight.co.uk
Mon Jan 14 20:57:52 UTC 2013


Hi All,
  I'm working on a project using an Arduino Uno to do various things in my motorhome. Was originally just going to be a heater controller, but now also going to be doing battery monitoring etc.

I need to take 4 analog readings from the battery bank (3 x current, 1 x voltage). I'm using hall effect sensors for the current which produce a 0-5v analog output proportional to the current.

I'm running out of analog inputs on my Uno and it would actually be an advantage to do the actual A/D conversion as near to the battery bank as possible. I'm thinking of a 4 (at least) channel ADC with a precision 5v reference communicating via I2C to the main Arduino (which would be a few meters away).

Anyone know a good chip to do this? I've found a few, but they are all SOT-23 form factor and I don't think my soldering skills are that good. I ideally want a DIP version.

This one looks pretty close, but uses SPI rather than ADC, which means I'd lose an extra 4 digital pins:
http://ww1.microchip.com/downloads/en/DeviceDoc/21298e.pdf

So to recap:

DIP packaging
at least 4 input channels
I2C
5v
12-bit input (10-bit at a push)

Another option would be to use another microcontroller and use its analog inputs. E.g. another ATMega chip in a barebones arduino-type setup and use 4 analog pins for my inputs, and 2 for I2C and *I think* can use the wire library to act as a slave and write the recorded analog inputs to the main Arduino. Seems kinda overkill though?

-Matt

-- 
Matt Hamilton, Technical Director
Netsight Internet Solutions Limited
http://www.netsight.co.uk/matth
Tel: 0117 90 90 90 1 Ext. 15

Registered in England No. 3892180
Registered office: 40 Berkeley Square, Clifton, Bristol, BS8 1HU




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