ADS1x15 ADC

Estimated reading: 3 minutes 280 views

Overview

A 4-channel ADC module that converts analog voltage levels to digital. Uses I2C interface.

Compatible Modules

ADS1015
ADS1115

Specifications (ADS1115)

ADC Bit rate: 16 Bit.
Interface Type: I2C.
Channels: 4 Channel AN0 AN1 AN2 AN3 or 2 differential inputs.
Input Voltage: 2.0 – 5.5V.
Channel Input Voltage: 0-VDD.
Continuous Mode: Only 150μA.
Single-Shot Mode: Auto Shut-Down.
Programmable Data Rate:8sps -860sps.
Input range programmed control, 7 types input ranges: -0.256V ~ + 0.256V, -0.512V ~ + 0.512V, -1.024V ~ + 1.024V, -2.048V ~ + 2.048V, -4.096V ~ + 4.096 V, -6.144V ~ + 6.144V

• For devices with 3.3V GPIO such as Raspberry Pi, BeagleBone, Jetson Nano, etc., the VDD of ADS1x15 must be connected to 3.3V.
• ADS1x15 requires I2C signal level of approximately 70% or higher of the VDD voltage. If 5V is connected to VDD and I2C signal is 3.3V, communication errors may occur or it may not work.
• If you need to connect sensors that output 0~5V, you must use a voltage divider to convert to 0~3.3V before connecting to ADS1x15. For details, refer here.

Resolution

Module	Single-Ended	Differential
ADS1015	0~2047	-2047~2047
ADS1115	0~32767	-32767~32767

Supported GPIO

Raspberry Pi 0~4
Raspberry Pi 5
BeagleBone Black/Green
Jetson Nano
FT232H, FT2232H, FT4232H
MCP2221

Commands

[INIT]

Configures initial settings.

Item	Type	Description
Module Selection	WRITE	Select the module type. (ADS1015, ADS1115)

[SET_GAIN]

Sets the gain value.

Item	Type	Description
Gain	WRITE	Select the input voltage resolution (Gain, Full scale). (2/3, 1, 2, 4, 8, 16)

[GET_GAIN]

Reads the gain value.

Item	Type	Description
Gain	READ	The currently set resolution (Gain, Full Scale).

[READ_SINGLE]

Reads the ADC value and voltage of single ended channels.

Item	Type	Description
ADC Ch0	READ	ADC output value of channel 0.
ADC Ch1	READ	ADC output value of channel 1.
ADC Ch2	READ	ADC output value of channel 2.
ADC Ch3	READ	ADC output value of channel 3.
Voltage Ch0	READ	Input voltage calculated from channel 0 ADC output value.
Voltage Ch1	READ	Input voltage calculated from channel 1 ADC output value.
Voltage Ch2	READ	Input voltage calculated from channel 2 ADC output value.
Voltage Ch3	READ	Input voltage calculated from channel 3 ADC output value.

[READ_DIFF]

Reads the ADC value and voltage of differential channels.

Item	Type	Description
ADC Ch0-Ch1	READ	ADC output value of channel 0 – channel 1.
ADC Ch0-Ch3	READ	ADC output value of channel 0 – channel 3.
ADC Ch1-Ch3	READ	ADC output value of channel 1 – channel 3.
ADC Ch2-Ch3	READ	ADC output value of channel 2 – channel 3.
Voltage Ch0-Ch1	READ	Input voltage calculated from channel 0 – channel 1 ADC output value.
Voltage Ch0-Ch3	READ	Input voltage calculated from channel 0 – channel 3 ADC output value.
Voltage Ch1-Ch3	READ	Input voltage calculated from channel 1 – channel 3 ADC output value.
Voltage Ch2-Ch3	READ	Input voltage calculated from channel 2 – channel 3 ADC output value.

Example

Objective

Connect a potentiometer to ADS1115 and display the ADC conversion value on the dashboard widget. Turn the potentiometer knob to verify that the ADC value also changes.

Parts

Part	Quantity
Raspberry Pi 4 *	1
ADS1115	1
Potentiometer (Variable Resistor)	1

* Other hardware can also be used. Refer to Supported GPIO.

Wiring

Connect each component to the corresponding connection as listed in each row below.

ADS1115	Potentiometer	GPIO
VDD	Pin 3 (Right)	3.3V
GND	Pin 1 (Left)	GND
SCL		3 (I2C1 SCL)
SDA		2 (I2C1 SDA)
ADDR *		GND
A0	Pin 2 (Center)

* The I2C address is determined by where the ADDR pin is connected as shown in the table below. This example uses 0x48. (May vary depending on module manufacturer.)