ADC - Board advice

Projects General Guidance
1

Hi guys,

I'm very new to all this so bare with me, i've been looking through the tech sheets but don't really understand the analogue to digital convertor.

I understand what one does, but basically, I want to put in multiple photodiodes into the board, which are analogue and gain a digital signal - what board would be best, i.e which has the most ADC's if they even have more than one.

Any help would be appreciated!

Simon

2

expand on this : "I want to put in multiple photodiodes into the board, which are analogue and gain a digital signal"

Here you can find all the mainstream arduino boards http://arduino.cc/en/Main/Products , you can find how many A/D inputs they have.

3

I've found a way of using analogue multiplexers, to place multiple analogue inputs into one adc, you access them via using a binary register, so each pin is looked at via the use of 001, 011.. 111 and all combinations between.

I don't want to buy a board and assume that because it has an analogue input, it can be converted to a digital output, or is that simply the case -if you place something analogue into the board on any of the pins; i see the due has 16 analogue inputs, will it simply run them through the ADC and give you a digital output?

basically aiming to map the light read of a photodiode and convert to to digital signal and then map for the creation of a grayscale image, the more inputs which convert to a digital signal I have, the more sensors I can use

4

The due and megagphave the most analogue inputs. There is only one A/D converter and these pins are switched inside the chip into it. As you have found you can use external multiplexers to switch any number of inputs you like to the A/D. Once inside the chip the analogue voltage is converted into a digital number between 0 and 1023 depending on the size of the voltage.

5

Grumpy_Mike:
The due and megagphave the most analogue inputs. There is only one A/D converter and these pins are switched inside the chip into it. As you have found you can use external multiplexers to switch any number of inputs you like to the A/D. Once inside the chip the analogue voltage is converted into a digital number between 0 and 1023 depending on the size of the voltage.

Thanks Mike,

I seem to remember someone pointing me towards you for some advice when I posted about this project last year.

That's exactly what I needed to know!

Simon