UnoCounter is a simple an Arduino Uno based trail counter that records each trail user detection event as an entry in a .CSV file on an SD card that can be collected and imported into a spreadsheet. It's the first trail counter that I built and deployed to validate the core project principle: using inexpensive off the shelf hardware components to build a workable counter. And it worked - you can build this counter by simply plugging things together.
Ardunino Uno is a ubiquitous platform that is available from many different suppliers and supported by lots of STEM educational kits, so it makes a good platform for getting started with this technology since you can ask any kid in your local school's robotics club for help if you get into trouble. Details on all this can be found at https://www.arduino.cc/ and there are many really good youtube videos to peruse.
UnoCounter is based on a standard Arduino Uno R3 board and the Arduino IDE development environment. The Uno board contains the microcontroller and is where all the software needed to create a trail counter runs. Several companies sell clones of this board or you can buy them on the arduino site. The official Arduino boards may cost a few dollars more, but helps to support the whole open source infrastructure around this technology.
The Arduino Uno ecosystem is populated by a host of supporting "shield" components that can be plugged into, or "stacked" on top of an Uno board. One of these shields provides nearly everything we need to support a trail counter: the Adafruit Data Logger shield for Arduino, available at https://www.adafruit.com/product/1141
The Data Logger shield adds two key capabilities to the counter: a Real Time Clock to keep track of the date and time, and a SD card interface that is used to record events to an SD card which can then be harvested and read by a laptop or computer.
In addition, the UnoCounter software supports an additional shield: an LCD Display Shield, available at https://www.adafruit.com/product/772 If present, this shield adds a handy user interface for testing and verifying your sensor operation and setup, but really doesn't add any value to the core mission - logging user detection events - and can be omitted.
That's it, aside from a battery and a detection sensor.
Internally, Arduino Uno boards operate on a 5V supply. You can use any battery capable of providing between 5 and 12 volts to power the stack, but the simple linear voltage regulators on these boards aren't terribly efficient and you'll get the best battery life at 5 volts. I've had best results with arrays of 4 1.2 volt rechargable NiMH cells.
The UnoCounter software can be found in UnoCounter.ino in this repository.
See Sensor Overview for more information on sensors.
I've typically used RCWL-0516 microwave sensors when using this trail counter. These sensors can be powered directly from the board (using the GND and 5V pins and the output logic signal can be tied to one of the input pins (I used DIO 3 in the softwear). This sensor works best when located a couple inches away from the arduino boards and battery, with no metal or electronics directly in front or behind the antenna area on the sensor board.