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ADS1115 analog-to-digital converter and Arduino

The ADS1115 device is a precision, low-power, 16-bit, I2C-compatible, analog-to-digital converters (ADCs) offered in an ultra-small, leadless, X2QFN-10 package, and a VSSOP-10 package. The  device incorporates a low-drift voltage reference and an oscillator. The converter also incorporates a programmable gain amplifier and a digital comparator. These features, along with a wide operating supply range, make the converter well suited for power- and space-constrained, sensor measurement applications.

The ADS1115 perform conversions at data rates up to 860 samples per second (SPS). The PGA offers input ranges from ±256 mV to ±6.144 V, allowing precise large- and small-signal measurements. The converter features an input multiplexer  that allows two differential or four single-ended input measurements. Use the digital comparator in the ADS1115 for under- and overvoltage detection.

The ADS1115 operates in either continuous-conversion mode or single-shot mode. The devices are automatically powered down after one conversion in single-shot mode; therefore, power consumption is significantly reduced during idle periods.

ADS1115 Features

Wide Supply Range: 2.0 V to 5.5 V
Low Current Consumption: 150 µA
(Continuous-Conversion Mode)
Programmable Data Rate: 8 SPS to 860 SPS
Single-Cycle Settling
Internal Low-Drift Voltage Reference
Internal Oscillator
I2C Interface: Four Pin-Selectable Addresses
Four Single-Ended or Two Differential Inputs
Programmable Comparator
Operating Temperature Range: –40°C to +125°C

 

Parts List

This module will cost less than $2

Amount Part Type
1 ADS1115
1 UNO R3 CH340G/ATmega328P, compatible for Arduino UNO R3

 

Schematics/Layout

 

In the layout below we just show the Arduino and sensor , for test purposes we connect A0 to A3 to various voltages for test purposes

 

arduino and ads1115 layout

arduino and ads1115 layout

 

 

arduino and ads1115 schematic

arduino and ads1115 schematic

 

 

Code

Again we use a library and again its an adafruit one – https://github.com/adafruit/Adafruit_ADS1X15

 

#include <Wire.h>
#include <Adafruit_ADS1015.h>
 
Adafruit_ADS1115 ads(0x48);
 
void setup(void)
{
Serial.begin(9600);
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)");
 
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

Open the serial monitor and you should see something like this

AIN0: 17707
AIN1: -1
AIN2: 26295
AIN3: -1

AIN0: 17702
AIN1: -1
AIN2: 26291
AIN3: -1

AIN0: 17706
AIN1: -1
AIN2: 26289
AIN3: -1

AIN0: 17700
AIN1: -1
AIN2: 26349
AIN3: -1

 

Video

In this video we compile and program the Arduino and show you the output. We also show a layout and schematic in fritzing, we tied the A0 to A3 to various voltages, at the end we removed these so the input is ‘floating’

 

Links

http://www.ti.com/lit/ds/symlink/ads1115.pdf

I2C ADS1115 16 Bit ADC 4 channel Module with Programmable Gain Amplifier 2.0V to 5.5V RPi

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