[UPDATE] Data logger design has been revised after testing with the first prototype I assembled.
This is an open source data logger design that is in its prototype stage. I started designing arduino-based data acquisition devices as an answer to the problem of expensive lab data acquisition systems used in most high school and university science labs in the USA. The Open Source Physics Laboratory data acquisition system version 2.0 I designed in 2012 received the first award and low cost award at American Association of Physics Teachers Apparatus Competition in 2013. It was based on Arduino UNO. This particular version I am prototyping now is definitely a different approach to the problem and it can be used for general data logging or as a platform for any electronics projects.
Unlike my other current design with almost completely surface-mount components and lots of capabilities (pictures 1 and 2), this new design exclusively uses thru-hole components and various breakout boards that are widely available cheaply on ebay.com or other electronic component outlets. The goal of this design is to make the data logger extremely cheap yet the very easy to assemble by beginners, i.e. science teachers, students and DIY hobbyists. Assembling the more capable logger design is not feasible to beginners.
Modules such as Arduino Nano clone, breakout boards for real time clocks, Micro SD card, DC-DC step-up converters, analog-to-digital converters, Inertial measurement units, etc. are extremely cheap, in most cases, a whole breakout board (say Arduino Nano clone) is cheaper than the main component (ATMEGA328P-AU), if you purchase the component from a US vendor, even at moderate quantity. So if I design a circuit board to host these components and help beginners construct a data logger from these components, many more people will be interested in trying, than trying the more capable logger with all surface-mount components.
At the same time, ebay parts are not the best of all parts. I have had issues with some parts I purchased off ebay. If someone unfortunately soldered one a defective component to the logger, it will be very frustrating indeed possibly to the point that he decides to stop trying electronics altogether. So to prevent such problem (always happens), I designed a testing board. After assembling the testing board, one will be able to plug in the Arduino Nano clone to test all the pins (I had some that had pins that didn't work), real time clocks, MicroSD card, etc. without permanently soldering them to the logger board so that they know all parts are in good order before assembling.
This is definitely a different type of design for manufacturing, if you consider this design may get"manufactured"one or two at a time by novices.
As this project moves towards completion, I will add bill of materials, testing code to test out the components and pictures and videos of assembling and testing with some sample projects.
Here is a list of components you need:
Data logger PCB from seeedstudio fusion
Testing board PCB from seeedstudio fusion (you only need one board but their minimal order might be 5)
Arduino Nano clone from ebay or other cheap sources
RTC break out board from ebay or other cheap sources
Micro SD card break out board from ebay or other cheap sources
DC-DC step-up converter break out board from sparkfun or ebay
Rotary encoder from reputable vendor such as mouser.com. The shaft needs to be at least 25mm long.
MC23008 DIP IC from reputable vendor such as mouser.com
Polycase enclosure and a bag of mounting screws
16X2 HD44780 LCD. Make sure this is not overly thick. You may need to find longer mounting screws otherwise.
The testing board is easy to assemble. All the holes are on 0.1 inch matrix so you can use a bread board to hold your components such as male headers while you solder. Female headers have long pins so they go through the board and have enough length to be plugged into a breadboard, effectively get held in place while you solder.
Start with the resistor, LED, and the potentiometer, then male headers and then move on to female headers.
First attach Arduino Nano clone and a female-female jumper to pin LED. Start the first test. All Arduino Pins D2 to D13, A0 to A5) will be toggled. If you jump LED with an Arduino pin and it doesn't blink the LED, this pin is either broken or not soldered on. Either replace the Nano with another one or attempt to fix it.
Next attach one component at a time and run tests on them:
Now you are safe to assemble the data logger. Assemble in the following order is recommended:
Resistors and fuse
Step-up converter, ADS1115 (optional), RTC (optional), IMU (optional) in any order
Battery holder wires
Arduino Nano clone
Straighten out the pins on MicroSD card holder and solder it to the logger
Two 12-pole screw terminal blocks
Two 6-pin female headers for LCD
Attach male headers to the LCD
Attach the LCD to the enclosure top cover
Secure the assembled board to the enclosure bottom cover
Insert two new AA batteries
Close the enclosure
Your are done!
Use the data logger as an Arduino Nano. Study the pin out of the screw terminal blocks and find some interesting projects to do.
The following libraries are required to drive the logger
sdfat or standard SD library in Arduino IDE