ADS1115 and ESP32 How to measure voltage?[Video]

For microcontrollers without an analog-to-digital converter or if you prefer a higher-precision ADC, the ADS1115 provides 16-bit precision at 860 samples/second through I2C. The chip can have four single-ended input channels or two differential input channels. To help boost smaller single/differential signals across the full range, an adjustable gain amplifier (up to x16) is incorporated. This ADC can measure a wide range of signals and is powered from 2 to 5 volts. It's also quite simple to operate.

The ESP32 is a single-chip 2.4 GHz Wi-Fi and Bluetooth combination chip manufactured using TSMC's ultra-low-power 40 nm technology. For a wide range of applications and power profiles, it is developed and optimized for the best power performance, RF performance, robustness, versatility, features, and dependability.

ESP32 Features

Processors:

• CPU: Xtensa dual-core (or single-core) 32-bit LX6 microprocessor, operating at 160 or 240 MHz and performing at up to 600 DMIPS

• Ultra-low-power (ULP) co-processor

• Memory: 320 KiB RAM, 448 KiB ROM

• Wireless connectivity:

• Wi-Fi: 802.11 b/g/n

• Bluetooth: v4.2 BR/EDR and BLE (shares the radio with Wi-Fi)

Peripheral interfaces:

• 34 × programmable GPIOs

• 12-bit SAR ADC up to 18 channels

• 2 × 8-bit DACs

• 10 × touch sensors (capacitive sensing GPIOs)

• 4 × SPI

• 2 × I²S interfaces

• 2 × I²C interfaces

• 3 × UART

• SD/SDIO/CE-ATA/MMC/eMMC host controller

• SDIO/SPI slave controller

• Ethernet MAC interface with dedicated DMA and planned IEEE 1588 Precision Time Protocol support[4]

• CAN bus 2.0

• Infrared remote controller (TX/RX, up to 8 channels)

• Motor PWM

• LED PWM (up to 16 channels)

• Hall effect sensor

• Ultra-low-power analog pre-amplifier

Security:

• IEEE 802.11 standard security features are all supported, including WPA, WPA2, WPA3 (depending on the version)[5] and WAPI

• Secure boot

• Flash encryption

• 1024-bit OTP, up to 768-bit for customers

• Cryptographic hardware acceleration: AES, SHA-2, RSA, elliptic curve cryptography (ECC), random number generator (RNG)

• Power management:

• Internal low-dropout regulator

• Individual power domain for RTC

• 5 μA deep sleep current

• Wake up from GPIO interrupt, timer, ADC measurements, capacitive touch sensor interrupt

 ADS1115 Features

• Ultra-Small X2QFN Package:

• 2 mm × 1.5 mm × 0.4 mm

• Wide Supply Range: 2.0 V to 5.5 V

• Low Current Consumption: 150 µA

• (Continuous-Conversion Mode)

• Programmable Data Rate:

• 8 SPS to 860 SPS

• Single-Cycle Settling

• Internal Low-Drift Voltage Reference

• Internal Oscillator

• I2C Interface: Four Pin-Selectable Addresses

• Four Single-Ended or Two Differential Inputs (ADS1115)

• Programmable Comparator (ADS1114 and ADS1115)

• Operating Temperature Range:

• –40°C to +125°C

ESP32 Pinout

ADS1115 Pinout

ADS1115 Block diagram

ESP32 Block diagram

ESP32 Applications

• Generic low power IoT sensor hub

• Generic low power IoT loggers

• Video streaming from the camera

• Over The Top (OTT) devices

• Music players

  – Internet music players

  – Audio streaming devices

• Wi-Fi enabled toys

  – Loggers

  – Proximity sensing toys

• Wi-Fi-enabled speech recognition devices

• Audio headsets

• Smart power plugs

• Home automation

• Mesh network

• Industrial wireless control

• Baby monitors

• Wearable electronics

• Wi-Fi location-aware devices

• Security ID tags

• Healthcare

   – Proximity and movement monitoring trigger devices

   – Temperature sensing loggers

ADS1115 Applications

• Portable instrumentation

• Consumer goods

• Battery monitoring

• Temperature measurement

• Factory automation and process controls

For the I2C connection, the ESP32 GPIO21 and GPIO22 are used. With the A0 pins of the ADS1115, connect the analog signal to the voltage you want to measure.

ESP32 includes two built-in ADC modules, ADC0 and ADC1, with each channel having a 12-bit resolution. But, as mentioned in the ESP32 ADC lesson, the fundamental difficulty with ESP32 ADCs is that they have non-linear properties and display non-linear behavior. It can't tell the difference between 1mV and 2mV signals, hence it has a limited resolution. We can use an external high-resolution programmable ADC IC to fix these problems.

ASD1115 Package information

ESP32 Package information