This article explains how to use the built-in 4-channel @ 10 bit A/D converter lines
The A/D converter input lines are available on the following pins:
Signal |
Description |
CORE9G25 |
3.3V |
3.3 volt power line |
W24 |
AVDD |
Clean 3.24V out for A/D circuitry |
|
VREF |
A/D voltage reference input |
W19 |
AGND |
Analog GND |
|
AD0 |
Analog input 0 |
W20 |
AD1 |
Analog input 1 |
W21 |
AD2 |
Analog input 2 |
W22 |
AD3 |
Analog input 3 |
W23 |
GND |
Digital GND |
W1 |
By wiring the VREF pin to AVDD or VDD (max 3.3 volt) it's possible to read a max voltage of 3.24 volt with a resolution of 10 bit (1024 samples). In this way the max sample resolution we obtain is about 3.24V/1024 ~= 3mV.
On VREF no voltage higher than 3.3 Volt can be applied. If you need to read a higher signal use a schematic like this:
Reading the A/D converter lines: