Ever intrigued by little boxes and blueprints, Jonni Bidwell explores a Pipowered Internet of Things hub that you can redesign yourself.
Wireless Things is the new name for Ciseco, the Nottingham-based Internet of Things company responsible for the critically acclaimed EVE Alpha device. EVE is a compact device that fits snugly on top a Raspberry Pi, connecting via the GPIO pins. There are a plethora of modules that can be fitted to the EVE board: SRF or RFM12B radios, real-time clocks (RTCs), temperature sensors and more. With the OpenPi, Wireless Things hope to take this idea one step further and it’s in the middle of a crowdfunder as we write this (http://bit.ly/KickstartOpenPi).
Using the Raspberry Pi Compute Module as a base, OpenPi provides two USB ports, a RTC (battery is included), 868-915 MHz SRF transceiver (for long range serial connections) and a temperature sensor. All this is boxed up in a tidy plastic case emblazoned with the Wireless Things logo, and apertures allowing HDMI and power connections. In terms of extensibility, you get 18 (plus two power) GPIO pins (which you'll need to break out yourself), headers for SRF and USB EEPROM programming, as well as wire-by-hand pins for connection to Wireless Things' XBee module. The Compute Module has 4GB eMMC storage onboard which houses a mostly-standard Raspbian install (PuTTY is included for easy serial connections), but this can be reflashed.
For the hobbyist user, it could be that a humble, standard issue Raspberry Pi will do the job, you can add the transceiver and RTC and any other peripherals easily and cheaply. It may not be a very tidy arrangement, but you can probably Macguyver yourself a suitable container using Lego, gaffer tape or a cigarette packet. A single basic OpenPi pack (comprised of just the Pi Compute module and OpenPi PCB mounted in a case) costs £49 inc VAT, so it comes down to whether having it all in a convenient box is valuable, and whether you will miss the line out and Ethernet connectors.
Open hardware
What is unique about OpenPi is that all the board schematics are open source – you can download them as EagleCAD files. In so doing, OpenPi aims to make it easier to make the Compute Module a more flexible platform upon which to develop projects and products. Manufacturer research suggests that form is as important as function, and that this partly explains the hitherto lacklustre uptake of the Compute Module as a platform. They claim that while no single design will suit everyone, using the OpenPi as a reference point will greatly simplify the design process for any budding IoT entrepreneur. So the product is really targeting those with ideas and industrial aspirations. Quantity discounts are available (10% for more than 100, 30% for five-figure orders) which speaks to this, but also makes the device more for educators.
We found that getting access to the RTC on our prototype required loading a module and sending some bytes to the i2c bus. The thermal sensor can easily be queried with i2cget, but the raw sensor data needs to be re-ordered and scaled to give correct reading. These are things that will be addressed come launch day, it's just a question of making some wrappers. The Kickstarter ends on 4 March 2015, and a release is planned for the end of March.
Specs
- Raspberry Pi Compute Module: Broadcom 2305 SoC 700MHz, 512 MB RAM (shared with GPU), 4GB eMMC storage
- OS: Raspbian
- Ports: 2x USB 2.0, HDMI, 2x micro USB (power & programming)
- RTC: TI BQ3200
- Temp Sensor: Ti TMP1000NA
- Sub-GHz Wireless: Wireless Things SRF