High-resolution analog ins

Hi all,

Trying to get started on a faderboard project for the Arduino, I've read the API and had a look at what some other people are doing (the realtime audio is particularly cool...). I've use ATMEGA chips before, but in very different capacities, not to mention with different APIs.

Couple questions: - Can anyone point me toward a good tutorial set and documentation other than the official arduino.cc API? - Is anyone selling built IO shards? I can't seem to find any... The chips here cost more than the assembled board plus shipping, so I'm looking for assembled stuff.

As for my implementation question, I really need high-resolution analog inputs. The default analogRead() call only returns 10-bit integers, which is sort-of-but-not-really sufficient for what I have in mind. Are there any existing implementations for using two inputs or an external ADC to get a higher bit-depth?

Thanks for any help!

I don't want to discourage you, but if you do use a higher resoluion ADC, then you'll need to be very careful with the circuit design to avoid noise problems. All the digital noise in the digital parts of the circuit will couple into the analog parts, and with higher resolution analog conversion, you'll be able to detect it. You'll need to take extra care with grounding, power supply decoupling, screening and choice of low-noise components.

There is example code on the playground using an MCP3208 12 bit 8 channel ADC with SPI interface. I've used them with good results. 12 bits is 4 times the resolution of 10 bits.

As Anachrocomputer says, the more resolution you attempt, the more your analog circuit design matters. I didn't worry too much about 12 bits, but if you're going for something extreme (IIRC I've seen 24 bit ADCs out there) you must start paying attention to the analog side of things.

-j

with an LTC2400 you have a nice 24 Bit ADC. I tested it on a breadbord and had between 18 and 20 bit effective resolution.

martin

http://interface.khm.de/index.php/labor/experimente/connect-a-ltc2400-high-precision-24-bit-analog-to-digital-converter/