Hi Guys,
I am working on a system based on the Arduino Due processor, unfortunately the engineer that designed the system is not around anymore and didn't leave much in the way of documentation. I am looking to add an additional analogue input and upon looking at the software and circuit diagram all of A0-A11 inputs are in use. The unusual thing is that A6-A11 are being used as digital outputs to fire various external relays. I was wondering if anyone could shed some light on why the engineer that designed this system would have used the very limited analogue inputs as digital outputs when there are many digital outputs still available (D7,D8,D9,D11,D12 etc.). From what I can see the current output and sink of the analogue inputs are worse than that of the digital outputs 3/6ma vs 15/9ma. Is the any valid reason why he would have done this and could I potentially switch to using digital outputs as a means to fire the relays? Apologies if there is something obvious, I tend towards the software side of things and don't usually dive into the electronics as much.