Analog Sensor Board¶
The SmartCitizen Analog Sensor Board (ASB) is an expansion board for the Smart Citizen Kit that provides connectivity to analog sensors with a high precission ADC (Texas ADS1115) via I2C, with four configurable addresses. It also gives the possibility to directly hook up this ADC by Adafruit.
We use it to measure analog voltages from low power sensors such as the Alphasense Ltd. electrochemical sensors, or SPEC sensors. You can use it in different configurations and the different headers:
Below you see a comparison:
Features¶
The Analog Sensor Board features two TI ADS1115 16bit 4-channel ADCs, and can read 8 analog channels in total. It has a potential to read up to 16 channels by daisy chainning two boards (by changing the address with the selectable jumper), or many more if you use a multiplexer.
Previous version
A previous version could interface 4 channels, daisy chainable up to 4 boards - with a total of 16 analog channels, by using Adafruit ADS1115 Breakout board.
Below you have a functional diagram:
The Analog Sensor Board natively operates at 3.3V, but can work up to 5.5V with a selectable jumper through a step-up converter (RECOM 0309S), making the digital voltage consistent with the sensor measurement voltage. To make everything consistent, it integrates a level-shifter from the GROVE connector's voltage to the internal voltage. Digital communications, via the Grove port, is done via I2C, from 3.3V up to 5.5V.
Design files¶
You can find all the design files for the different versions of the Analog Sensor Board in the hardware repository.