16-bit I2C ADS1115 module, 4-channel ADC with professional PGA gain amplifier
The ADS1115 is a 16-bit external ADC digital analog converter + a programmable gain amplifier (or PGA) that has built-in, which can be very useful for certain projects with Arduino and ESP8266 NODEMCU. It is ideal when more resolution or more analog pins are needed.
 
For example, Uno Arduino incorporates 6-10-bit ADCs, however, ADS1115 has a 16-bit resolution. On the other hand, using an external ADC digital analog converter, you can release the processor. In the case of the ESP8266, it incorporates only a 10-bit digital analog converter that values in the 0V and 1V range. This makes the conversion depend on the resistors that are used to make the stress divider.
Using ADS1115 you will gain a lot in accuracy and conversion quality.
Communication between the ads1115 Arduino or ESP8266 external digital analog converter is via I2C.
It also has a comparator mode in which ADS1115 generates an alert by the ALERT pin when any of the channels exceed a threshold value that we set per code.
Finally, the ADS1115 incorporates a PGA that allows you to adjust the gain from 6,144V to 0.256V. This allows for greater accuracy when measuring voltages below 5V.
Regardless of the PGA chosen, the maximum voltage we can measure will always be the supply voltage. That is, even if the PGA is 6,144V, we will not be able to measure voltages greater than 5V
 
The ADDR pin determines the I2C address of the device. The default mode is to connect the ADDR pin to the GND, which results in 0x48.