Home

Why phyphox?

phyphox (physical phone experiments) is an app developed by the 2nd Institute of Physics of the RWTH Aachen University. It allows you to conduct a wide range of experiments using the inbuilt sensors of your smartphone. What separates it from other apps that expose sensor data from your phone is:

• the creation of 'experiments' in phyphox mean we can create custom views for common demonstrations / experiment meaning no further processing needed on another device
• The phyphox Arduino library allows for a simple workflow from a student / teacher perspective, the experiments definitions exist on the devices so no sending of files - simply connect -> download experiment via Bluetooth from device -> use
• Using phyphox allows us to have a fully functioning GUI for the data we are collecting from our sensors
• Our experiments would be alongside the existing experiments that use the on board sensors of the phone. One app for all experimentation

Why the Adafruit ESP32 Feather V2?

We chose the ESP32 chip for its networking capabilities (WiFi and Bluetooth) combined with a reasonable price point and wide support in the maker community. The Adafruit ESP32 Feather V2 was specifically chosen for its compact layout and full features:

• It has a STEMMA QT port - allows for solder free connection to a vast array of sensors from not only Adafruit but also Sparkfun, Seeed Studio, M5Stack and others
• The STEMMA QT port is in a good location - many boards have it next to the USB port, making case design harder (dream would be an edge connection)
• USB-C - wide availability of cables, forward looking
• Onboard Neopixel RGB LED - useful for user feedback and as a light source in some experiments
• Lipoly battery port and battery monitoring pin - makes it possible to have wire free devices
• Low power draw - allows us to make use of the ESP32's deep sleep functionality
• Multiple mounting holes of a standard size - M2.5 mounting holes make them the same size as many sensor boards allowing for simple hardware purchasing

The Adafruit Feather is a family of microcontroller main-boards designed to a standard specification. Adafruit have a long history of designing and supporting boards in this format.

It is not the cheapest board and there are more compact layouts available, but often these are available only on AliExpress/Ebay and aren't as fully featured. Adafruit supporting the maker community with not only their hardware but their excellent libraries and documentation is something we are willing to pay for. That said if you select a different ESP32 board much of the code written in this project will be compatible.

Purchasing components

Components have been chosen as much as possible such that they can be bought from UK based electronics retailers that specialise on the Maker community. The two websites that will be linked most often in the build guides are Pimoroni and The PiHut. They both have educational discounts available through their wholesale platform - linked from their respective websites. US based readers will be able to buy many components directly from Adafruit.

For hardware we wanted to be able to build most of the devices using a standard box of fastenings to avoid having to piece together a collection from many sources. The cases have been designed around the following box of M2.5 fastenings - UK -> The PiHut 103126 / US-> Adafruit - ADA3299.