Sparkfun Artemis Nano analog reference?

Development Boards Artemis
1

Hey Sparkfun. I’ve got your Artemis Nano board and am having trouble with getting pots to measure their full range. They zero out well, but only measure about 2/3rds of the way through the swipe. I’ve got them hooked up with one side pin on ground, the other side pin on 3.3v, and the middle pin on A2. Multimeter shows 3.3v at the pot. The pot model is WH148 and is supposed to be a 10k linear taper. I’ve striped the program down to bare essentials. Is the nano’s analogreference set to 5v while its outputting 3.3v? Or am I doing something else wrong?

void setup() {

pinMode(A2, INPUT);

Serial.begin(9600);

}

void loop() {

Serial.println(analogRead(A2));

delay(10);

}

2

What happens if you connect the #V3 directly to A2 ?

Do you slowly turn the pot ? See viewtopic.php?f=169&t=54907

3

Saw this in a hookup guide:

Note: Be aware that the ADC input range is from 0 - 2V. Although connecting a sensor with an output to 3.3V is safe for the Artemis module, it will saturate the ADC at 2V.

4

YellowDog:
Saw this in a hookup guide:

Note: Be aware that the ADC input range is from 0 - 2V. Although connecting a sensor with an output to 3.3V is safe for the Artemis module, it will saturate the ADC at 2V.

I think this is the issue I’m having. The board puts out 3.3v and the ADC maxes out at 2v so it counts that as the max value. Seems easy enough to work around but what would be the strategic value of that?

5

The Apollo3 chip ADC works with 2 references voltages: 2V or 1.5V. They can be sourced internal or external, in case of Artemis the internal 2V is used.