ADS1115 help

Projects Programming
1

Uno R3
arduino IDE 1.0.5-R2
example tutorial this is all based on:

I'll start off by saying I've got no formal training in programming, I'm completely self taught via the internet, and I still don't know much at all.

I have the ADS1115 breakout board and the tutorial provided favors the ADS1015 so I have a few questions. I am using the ADS1115 to read a pressure transducer that has mV output(0-5 psi=0-25mV @5V excitation). I have the Vs pin connected to the arduino 5V, I have the gnd pin connected to arduino ground, the V+ pin is connected to A0, and the V- pin is connected to A1. I have a syringe and some tube I'm using to put pressure on the transducer. Running the sample code, I can see the values shift as I apply pressure.

If I run the example code from the tutorial with everything as ADS1015 it works, but if I edit the code to ADS1115, it does not.

This works:

#include <Wire.h>
#include <Adafruit_ADS1015.h>
 
Adafruit_ADS1015 ads1015;
 
void setup(void)
{
  Serial.begin(9600);
  Serial.println("Hello!");
  
  Serial.println("Getting differential reading from AIN0 (P) and AIN1 (N)");
  Serial.println("ADC Range: +/- 6.144V (1 bit = 3mV)");
  ads1015.begin();
}
 
void loop(void)
{
  int16_t results;
 
  results = ads1015.readADC_Differential_0_1();
  Serial.print("Differential: "); Serial.print(results); Serial.print("("); Serial.print(results * 3); Serial.println("mV)");
 
  delay(1000);
}

This is from the serial monitor:

Hello!
Getting differential reading from AIN0 (P) and AIN1 (N)
ADC Range: +/- 6.144V (1 bit = 3mV)
Differential: 0(0mV)
Differential: 0(0mV)
Differential: -9(-27mV)
Differential: 5(15mV)
Differential: 0(0mV)
Differential: 0(0mV)
Differential: 0(0mV)
Differential: 0(0mV)
Differential: 0(0mV)
Differential: 0(0mV)
Differential: 5(15mV)
Differential: 15(45mV)
Differential: 15(45mV)
Differential: 15(45mV)
Differential: 11(33mV)
Differential: 0(0mV)
Differential: 0(0mV)
Differential: 0(0mV)
Differential: 0(0mV)

If I edit it to this it does not work:

#include <Wire.h>
#include <Adafruit_ADS1115.h>
 
Adafruit_ADS1115 ads1115;
 
void setup(void)
{
  Serial.begin(9600);
  Serial.println("Hello!");
  
  Serial.println("Getting differential reading from AIN0 (P) and AIN1 (N)");
  Serial.println("ADC Range: +/- 6.144V (1 bit = 3mV)");
  ads1115.begin();
}
 
void loop(void)
{
  int16_t results;
 
  results = ads1115.readADC_Differential_0_1();
  Serial.print("Differential: "); Serial.print(results); Serial.print("("); Serial.print(results * 3); Serial.println("mV)");
 
  delay(1000);
}

I get the error

'AdafruitADS1115' does not name a type

So am I still getting the full 16 bit resolution when I use the code with ADS1015 written everywhere? I assume this is an error internal to the library?

The next question is regarding the getGain command. How do I implement it to check the gain level on the ADC?

Thanks in advance,
Robert

2

#include <Adafruit_ADS1115.h>

Judging by the Adafruit page you don't change the include file, both devices are supported in the one library. That is why you got this:

'AdafruitADS1115' does not name a type

3

That fixed it! So I'm using this now:

#include <Wire.h>
#include <Adafruit_ADS1015.h>
 
Adafruit_ADS1015 ads1115;
 
void setup(void)
{
  Serial.begin(9600);
  Serial.println("Hello!");
  
  Serial.println("Getting differential reading from AIN0 (P) and AIN1 (N)");
  Serial.println("ADC Range: +/- 6.144V (1 bit = 3mV)");
  ads1115.begin();
  ads1115.setGain(GAIN_SIXTEEN);
}
 
void loop(void)
{
  int16_t results;
 
  results = ads1115.readADC_Differential_0_1();
  Serial.print("Differential: "); Serial.print(results); Serial.print("("); Serial.print(results * 3); Serial.println("mV)");
 
  delay(1000);
}

Thanks!