Ethoscope core

This document describes the core of the ethoscope device. The "core" referes to device without arena or extra modules. it is made of three mainparts:

• the head, which contains the Raspebbery Pi and its camera.
• the base, which diffuses light though different types of arenas (read about arenas here).
• the side walls, which simply connect the head to the base.

An assembled core looks like this:

Building a core

A list of all components (or BOM) is available here.

So before we start, we should have something like:

In addition, you will need several tools and consumables such as:

• Allen keys
• soldering iron
• super glue
• heat shrink
• solder wire (lead free).

GPIO connector

In order to power the infrared (IR) light, the General Purpose Input Output (GPIO) of the Raspberry Pi is connected to the base by a ribbon cable. We can build a simple connector that looks like that:

Here, we have used a 21cm long 6 way ribbon cable.

Base

The base acts as an IR light box. The idea is to reflect IR light upward so it can go through the arena.

In order to put the light together, a little bit of basic soldering is required:

In the figure above, the yellow dashed lined indicate where we need to solder.

You can also notice that heat shrink have been put around the wires so that we ensure proper insulation.

After is has been soldered, the led strip must be passed from the outside to the inside of the light box by the connector hole. Then, we can stick the light to its support, and glue the support to the side of the base:

Head

The head is the single most important part of the device. It is made of a Raspberry Pi, and peripherals, enclosed by pair(lower and upper) of 3d printed parts.

The steps to build the head are the following:

1. Generate a SD card (it contains the operating system and all the software used by the ethoscope).
2. Plug the SD card in the Pi.
3. Place the camera on the lower part, and screw from the outside using M2 bolts along with the nylon nuts (sub-picture A, below).
4. Position the Raspberry Pi in the lower part, above the camera, and screw it from the outside, with two M3 bolts (sub-picture B, below).
5. Connect the camera, the GPIO connector and the wireless dongle to the Pi.
6. In the upper part, there are four holes in the corners. They allow us to close the box with screws. You want to insert a nut in each slit under the hole,
7. Now, we can close the box (sub-picture C, below) and screw the upper and lower parts together, using four M3 screws.
8. The last thing we want to do is plugging the micro-usb power supply in the Pi.

Last bits: Before you can start working, you will have to change the focus of the camera. I am afraid this has to be done manually. A very good explanation is available here(TODO).

The wireless dongle blinks with blue light to indicate that it transmits data. According to your expoerimental setup, you may want to blind the LED (e.g. with black tape) in order to prevent interference with the behaviour of your experimental animals.