Address Configuration
The address can be changed to one of four options (see the datasheet table 5) so you can have up to 4 ADS1115's connected on a single 2-wire I2C bus for 16 single ended inputs.
Source: Page 17 of ADS1115 Datasheet (https://cdn-shop.adafruit.com/datasheets/ads1115.pdf).
Library and sample sketch
The sample code and library can be found at - https://www.adafruit.com/product/1085.
Note that because 1 bit is used to indicate "+" and "-", the actual resolution of the ADC is 15 bits (2 ^ 15 = 32768). Therefore, for the default 2/3 gain, the detection range is +/- 32768 x 0.1875mV = 6144mV (+/-6.144V) which is good for 5V circuit.
For 3.3V circuit, the 1x gain could be used for better resolution (+/- 32768 x 0.125mV = 4096mV (+/- 4.096V).
Sample Sketch (using the default setting of 2/3x gain)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | #include <Wire.h>
#include <Adafruit_ADS1015.h>
Adafruit_ADS1115 ads; /* Use this for the 16-bit version */
//Adafruit_ADS1015 ads; /* Use thi for the 12-bit version */
void setup(void)
{
Serial.begin(115200);
Serial.println("Hello!");
Serial.println("Getting single-ended readings from AIN0..3");
Serial.println("ADC Range: +/- 6.144V (1 bit = 3mV/ADS1015, 0.1875mV/ADS1115)");
// The ADC input range (or gain) can be changed via the following
// functions, but be careful never to exceed VDD +0.3V max, or to
// exceed the upper and lower limits if you adjust the input range!
// Setting these values incorrectly may destroy your ADC!
// ADS1015 ADS1115
// ------- -------
// ads.setGain(GAIN_TWOTHIRDS); // 2/3x gain +/- 6.144V 1 bit = 3mV 0.1875mV (default)
// ads.setGain(GAIN_ONE); // 1x gain +/- 4.096V 1 bit = 2mV 0.125mV
// ads.setGain(GAIN_TWO); // 2x gain +/- 2.048V 1 bit = 1mV 0.0625mV
// ads.setGain(GAIN_FOUR); // 4x gain +/- 1.024V 1 bit = 0.5mV 0.03125mV
// ads.setGain(GAIN_EIGHT); // 8x gain +/- 0.512V 1 bit = 0.25mV 0.015625mV
// ads.setGain(GAIN_SIXTEEN); // 16x gain +/- 0.256V 1 bit = 0.125mV 0.0078125mV
ads.begin();
}
void loop(void)
{
int16_t adc0, adc1, adc2, adc3;
adc0 = ads.readADC_SingleEnded(0);
adc1 = ads.readADC_SingleEnded(1);
adc2 = ads.readADC_SingleEnded(2);
adc3 = ads.readADC_SingleEnded(3);
Serial.print("AIN0: "); Serial.println(adc0);
Serial.print("AIN1: "); Serial.println(adc1);
Serial.print("AIN2: "); Serial.println(adc2);
Serial.print("AIN3: "); Serial.println(adc3);
Serial.println(" ");
delay(1000);
}
|
Output
Note, The default gain is 2/3 gain (1 bit = 0.1875mV).
The gain is set to 1x gain in the sketch below.
Sample Sketch (using 1x gain)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | #include <Wire.h>
#include <Adafruit_ADS1015.h>
Adafruit_ADS1115 ads; /* Use this for the 16-bit version */
//Adafruit_ADS1015 ads; /* Use thi for the 12-bit version */
void setup(void)
{
Serial.begin(115200);
Serial.println("Hello!");
Serial.println("Getting single-ended readings from AIN0..3");
Serial.println("ADC Range: +/- 6.144V (1 bit = 3mV/ADS1015, 0.1875mV/ADS1115)");
// The ADC input range (or gain) can be changed via the following
// functions, but be careful never to exceed VDD +0.3V max, or to
// exceed the upper and lower limits if you adjust the input range!
// Setting these values incorrectly may destroy your ADC!
// ADS1015 ADS1115
// ------- -------
// ads.setGain(GAIN_TWOTHIRDS); // 2/3x gain +/- 6.144V 1 bit = 3mV 0.1875mV (default)
ads.setGain(GAIN_ONE); // 1x gain +/- 4.096V 1 bit = 2mV 0.125mV
// ads.setGain(GAIN_TWO); // 2x gain +/- 2.048V 1 bit = 1mV 0.0625mV
// ads.setGain(GAIN_FOUR); // 4x gain +/- 1.024V 1 bit = 0.5mV 0.03125mV
// ads.setGain(GAIN_EIGHT); // 8x gain +/- 0.512V 1 bit = 0.25mV 0.015625mV
// ads.setGain(GAIN_SIXTEEN); // 16x gain +/- 0.256V 1 bit = 0.125mV 0.0078125mV
ads.begin();
}
void loop(void)
{
int16_t adc0, adc1, adc2, adc3;
adc0 = ads.readADC_SingleEnded(0);
adc1 = ads.readADC_SingleEnded(1);
adc2 = ads.readADC_SingleEnded(2);
adc3 = ads.readADC_SingleEnded(3);
Serial.print("AIN0: "); Serial.println(adc0);
Serial.print("AIN1: "); Serial.println(adc1);
Serial.print("AIN2: "); Serial.println(adc2);
Serial.print("AIN3: "); Serial.println(adc3);
Serial.println(" ");
delay(1000);
}
|
Output
Note, The gain is set to 1x gain (1 bit = 0.125mV).
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