ADS1115 problems or fake?

Other Hardware Sensors
1

Hey guys, I am new to coding and trying to set up the ADS1115 (± 16-bit analog digital converter) with various codes and libraries from the internet.

For test purposes, I tried to measure a 140mV voltage from a potentiometer. On the left side of the picture I have declared the ADS1115 as ADS1015 (± 12-bit analog digital converter) and everything works as desired -> 0.125mV / step.
It does not work as ADS1115 (right side picture), it always jumps directly by 16 (2^4) steps which results in the same accuracy -> 0.125mV/step (changing the programmable-gain-amplifier does not help with this issue). Since 2^4 is 4 bit and equals the difference between ADS1115 and ADS1015, I have the suspicion that the promised ADS1115 in reality is an ADS1015.

Any thoughts pls?

12bitcomp16bit.png
12bitcomp16bit.png1011×219 4.94 KB

2

My code is:

#include <Wire.h>
#include <Adafruit_ADS1015.h>

Adafruit_ADS1115 ads(0x48);  /* Use this for the 16-bit version */

float voltage = 0;
float ha = 0;

void setup(void) 
{
  Serial.begin(9600);
  Serial.println("Hello!");
  
  Serial.println("Getting single-ended readings from AIN1");
  Serial.println("ADC Range: +/- 0.256V (1 bit = 0,125mV/ADS1015, 0.0078125mV/ADS1115)");
  
  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;


  adc1 = ads.readADC_SingleEnded(1);
  ha = adc1;
  voltage = (ha/128);

  Serial.print("AIN1: "); Serial.print(adc1);Serial.print("-> mV:");Serial.print(voltage,4);
  Serial.println(" ");
  
  delay(1000);
}

I am using an "old" Arduino UNO and tried 2 different ADS1115 for the same manufacturer.

3

Did you try printing the digital output (0-32767) of the ADS1115.
Did it change in one digit steps.

Did you try
voltage = ha / 128.0;

Leo..

4

Where did you buy the chip? These days its very probably fake unless you buy from a reputable supplier...

5

Thank you for your replies! :slight_smile:

@Wawa

Yes, iam printing the digital output (0-32767) in the serial monitor as you can see in the picture (AIN1: XXXX).
No, it is changing in 16 digit steps.

I just tried "voltage = ha / 128.0;" but it did not change anything.

@MarkT
I bought them from Amazon "AZDelivery 3 x ADS1115 ADC Modul 16bit" for 10€ for all 3. On trustpilot they got a very bad rating.

6

Mouser, Digikey, Element14, etc are the places to get chips these days, the counterfeit scourge is extremely
bad these days. There a vast illegal cottage industry re-marking chips, some are recycled (and actually the
right chip, but used/untested), some are the wrong but similar chip, some are just empty packages. These
are offloaded onto eBay and Amazon associate sellers in vast numbers.

7

yes, but the shipping is more expensive than the actual item^^ so i went for amazon

thanks a lot guys

8

I bought a 3 pack of them from Amazon. All three work fine. Everything I have bought through Amazon which was HiLetgo was always reasonably priced and worked fine. That said there is no shortage of garbage coming in and distributed. For what I consider novelty stuff I am fine with Amazon but if it is a serious project I go with any of the reputable distributors. Before I retired I dealt quite a bit with Allied Elect so I frequently still use them.

Ron

9

ferdifuchs1:
I bought them from Amazon "AZDelivery 3 x ADS1115 ADC Modul 16bit" for 10€ for all 3. On trustpilot they got a very bad rating.

So the cheap modules you bought, are suspicously cheap, and get a bad rating.

These devices are £4.99 each from Farnell, shipping is free if the order is over £25.

So you bought them (from Amazon) just because they are cheap.