Digital/Analogue I/O extenders

Hi all,

Having been in electronics for years I am building a couple of shields for my own use, basically they are analog & digital I/O extenders. These will made as proper pcb's (not on proto board or anything).

I've decided to make a few of them as it keeps the price down when getting the pcb's I'll be selling a few via my own website, or possibly Ebay.

The first prototype of the first board is working and I'm just finalizing the demo code/sketch on how to use it (dead easy) which will be shipped with the board.

32 channel digital I/O extender (using I2C). All channels configurable as input or output. I2C addresses configurable via DIP switches. Outputs capable of 25mA each. Screw terminals (mini) for each I/O channel. Optional interrupt line back to Arduino. Footprint of board per standard Arduino.

I'll post back here with more news/photos when I get a production board assembled.

After that, I'll be looking at my next extender, a multi-channel DAC/ADC (true analogue input/output). Then after that who knows!



Have designed a couple more, the next few weeks will be great fun coding them (albeit the digital one is now finished).

So here's my portfolio thus far:-

  • 24ch 8-bit ADC 0-5vdc / 6ch 8-bit DAC 0-5vdc I2C Extender Board c/w mini screw terminals.
  • 12ch 8-bit DAC 0-5vdc I2C Extender Board c/w mini screw terminals.
  • 32ch Digital I/O I2C Extender Board c/w mini screw terminals.


How about using an ADC/DAC with more resolution, say 12 or 14 bits? Feel free to use/adapt my libraries for communicating with discrete/analog I2C devices:



Thanks for that.

Yes, 10 or 14-bit is on the cards.......these first 2off ADC/DAC pcb's are non-SMD (i.e. DIL IC), hence availability of 8-bit only. Mainly for my own use. I'm in the UK and SMD assembly houses are "rip -off Britain" prices.

I'm testing out a pcb maker in China (reduced costs)......and if all going well I'll get the SMD versions done.


UPDATE:- Great result, have found a 20pin DIL 10ch AtoD 10bit I2C IC......and it's cheap!