» By Joren on Wednesday 11 January 2017
The xOSC board by x-io technologies looks like a very nice solution in many interactive wireless setups. Judging from the specifications and documentation it offers a lot of value. It is basically a small WiFi transmitter with some sensors and a battery attached to it. The board also has some drawbacks. 1) It is expensive at about € 180. This is especially problematic if you need about five or so for your application.2) It seems that it is also hard to add extra sensors via SPI or I²C. 3)The battery needs to be removed to charge, which makes it harder to build into a fixed enclosure. This post describes an alternative based on the ESP32 platform that addresses these shortcomings.
The ESP32 is a micro-controller with a WiFi transmitter which can be programmed using the Arduino environment. Sparkfun has a thing called the ESP32 Thing which contains the ESP32 chip. It can be used to build an xOSC alternative.
- It costs about 20$, when you add a battery 5$ and a sensor 20$ (IMU) you end up with a 45$ price tag. The price of course depends on which exact sensor/battery you need for your application. A 500mAh lasts about two hours when sending 66 messages per second over WiFi (using UDP).
- The ESP32 Thing supports the Arduino environment which potentially allows you to use all available Arduino libraries and supported sensors. However, some libraries do contain hardware specific instructions which are often not ported yet. Since the hardware is rather new – large scale production started only 3 months ago – not many libraries have been ported. Fortunately a lot of libraries simply work without any changes. At hackaday they have been testing a few: ESP32 and Arduino libraries. I had success with the BNO55 library, it did not need any changes. The OSC library did need some small changes to operate as expected.
- The Thing contains a battery charging circuit. Once embedded into an enclosure the battery can stay in place. The software running on the device even keeps running when changing power sources.
Attached to this post you can find modifications to the Andriod OSC library that enable it to run on the ESP32: ESP32-Arduino-OSC-library together with a patch that sends random data over OSC. This should enable you to build an xOSC alternative.
Some drawbacks of the ESP32 is that the supporting software is quite immature. There is a Bluetooth chip on the ESP32 which is currently not supported in the Arduino environment. The setup can be somewhat challenging. The documentation can be improved. Some of the ESP32 Things seem to be unable to connect to old WiFi routers which can be problematic.