What is it?

An Arduino shield combining RRC (Resistor, Resistor, Capacitor) analog input processing, Real Time Clock port, OpenLog (PN DEV-13955) serial data recorder port, AT24CS08 digital serial number (to record the data source in multi-tenant systems), screw cage terminals, indicator LED (D13), push-button (D7), 10K pull ups on the digital pins (makes connecting to our Isolated Wide Voltage Range Interface Board easy) and level shifters for the I2C port (interface 3.3V Arduinos with 5V I2C devices like LCD displays) and serial data port (connect 5V Arduinos with 3.3V serial ports). This product contains a board with the SMD items already soldered, and the through hole connectors provided for assembly. The OpenLog and RTC modules are not included and need to be purchased separately if you need those functions. Note there are 8 RRC network channels on A0 - A7. The values of the resistors and capacitors will depend on the signals being monitored, so resistors and capacitors will need to be supplied if you want to monitor analog signals. On an UNO, only A0 - A3 can be used when the I2C port is used. On a Mega, all 8 channels can be used. A schematic is available on the datasheet link. Source Code Link has a sketch that can talk to the devices on the board, output recorded data on the serial TX pin and display data on a 20X4 LCD. This sketch can be modified to run the Arduino in a way useful to you.

Why did you make it?

I needed to do some data logging for hobbies like gardening and beer making, and to help a friend monitor some refrigeration units at his small business. After looking at a number of options, I settled on using an Arduino to acquire the digital and analog signals, and then sending the data over a serial connection in JSON packets for logging and data analysis. At first, a Raspberry Pi was used, but a switch to Arduino was made for the built in analog inputs, fast boot-up, low power options (can be battery/solar powered) and no OS to crash. Often a Raspberry Pi or other device with robust networking is added to process the data and push the results into the cloud.

What makes it special?

I could find shields that exposed Arduino pins on screw cage terminals, but they were direct connections. Often you will need to scale analog voltages down, or run them through a low pass filter prior to the A/D converters. Another place where direct connect pins can be a problem is when interfacing to systems with different voltages. Level converters were added on the I2C and serial ports to handle common voltage conversions. Arduinos typically lack a real time clock, so a port for the common DS3231 RTC module was added. To make this board and an Arduino a full data logger, a port was added for a DEV-13955 OpenLog module to record the data packets flowing out of the serial port. Because the data is some times pushed into the cloud, each monitoring system needs a unique ID. A AT24CS08 digital serial number was added so data will always be able to be separately tracked. Nothing on the board is cutting edge technology, but it combines a collection of support circuitry in a way I was not able to find. There are other data logging systems, but I wanted to control where and how data was stored and not be subject to a company going out of business or changing a design in a way that breaks current systems.