Testing the ADS1115

[brainfart]

I obtained an ADS1115 ADC breakout board recently and decided to connect it with a potentiometer to my Arduino UNO for testing purposes.

VDD to 5V on the Arduino
GND to GND on the Arduino
SCL to SCL
SDA to SDA according to the tutorial

http://learn.adafruit.com/adafruit-4-ch ... and-wiring

Connected a pot to 5V and GND on the UNO and the wiper output to A0 on the ADS1115.

Uploaded the Single Ended Conversion sketch from http://learn.adafruit.com/adafruit-4-ch ... rogramming
Now forgetting about the scaling for a moment I receive some weird results on the serial monitor: all the channels AIN0...3 have the same values, even though the potentiometer is connected to Analog In 0 only, and nothing is conneted to the other analog inputs.
How come AIN0 to 3 show the same values? Do I somehow have to connect them to GND with a resistor if nothing is connected to these inputs?
AIN0..ö.3 shows values from 0 to 1692, and it seems to be a 2KOhm pot. Do I have to change the gain to 16 to get more resolution?
2^16= 65536
65536/16 = 4096,
while my maximum reading is 1692, so I seem to get less that 14 bit resolution. How do I expand the resolution?

[adafruit_support_bill]

nothing is conneted to the other analog inputs.

With nothing connected, these inputs will 'float'. Their value is undefined, but it is likely that they would be influenced by an adjacent channel.

I seem to get less that 14 bit resolution.

First, you are using single-ended measurement. This limits you to 15 bits.
http://learn.adafruit.com/adafruit-4-ch ... onnections
Second, the default ADC range of the device is 6.144v. (although your input should never exceed 5v) So a full-scale 5v input will not use all 15 bits of resolution.

To double the resolution, you can use differential mode measurement. To increase it a bit more, you can change the default range (the appropriate constants are all defined in the library header file).