We need below boards and components for this project:
- ADS1115 ADC
- Arduino Uno board
- Jumper wires
- Trimmer potentiometer
- USB Type A to Type B cable
- Arduino Uno SHIELD (optional)
- Bread board
The connectivity is as shown in the below image.
ADS1115 is a 16-bit Sigma-Delay type 4-channel ADC which helps to read analog inputs. ADS1115 is interfaced to Arduino Uno using I2C interface.
The internal block diagram of ADS1115 is as shown below.
- Analog inputs are connected to a Mux and based on Mux selection input Analog channel can be selected
- The analog input can further be amplified using Pre-Gain amplifier (PGA) for very low level signals to be read
- There is an internal oscillator of 1 MHz and no need of external clock input
- There is an internal voltage reference and no need for voltage reference
To interface ADS1115 with Arduino Uno we have to use I2C pins on the Arduino Uno and I2C slave address is required for communication. As per the below table from ADS1115 datasheet, we can determine the address of the ADS1115 using the connectivity of the ADDR pin. We have ADDR connected to GND and on the above board through a 10K resistor and so the address is 1001000.
Below is the schematic diagram of the ADS1115 evaluation board.
From above schematic of ADS1115 evaluation board,
- ADDR has pull-down of 10K which determines the I2C address
- SCL and SDA has on-board pull-ups, so, no need of any other pull-ups
- ALERT pin has 10K pull-up
- All the 4 Analog pins, I2C pins, ALERT, ADDR pins are routed to connector
- Board can take any voltage between 2V to 5.5V
A trimmer potentiometer is used to provide voltage to the A0 pin of the ADS1115 ADC. How to use a trimmer potentiometer is described in the below link:
The below link describes the code and connectivity:
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