Wolfram Donat - Jumpstarting the Onion Omega2: An Introduction to a New Low-Cost Internet of Things Computer

Copyright 2018 Wolfram Donat. All rights reserved.

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I n the proud tradition of computers named after fruitthe Apple, the Raspberry Pi, the Banana Pi, the Pine (okay, maybe not that last one)comes a new entry into the small, single-board computer (SBC) market: the Onion Omega2.

Lets ignore the fact that an onion is a vegetable, not a fruit, and talk about the Onion Omega2s origins for a moment. The Onion Omega2 (and its big brother, the Omega2+) are the second offering from a company called, appropriately enough, Onion. The original Omega cost about $18 and ran on a Qualcomm Atheros AR9331 chip. Onion ran a Kickstarter campaign in 2016 to replace the Omega with the Omega2, using a different system on a chip, the MediaTek MT7688. They were ultimately successful, raising well over their goal of $440,000, and the Omega2 shipped late in 2016. A nice feature of the newer version was the price drop the new board started at $5, though it was later increased to $7.50. The Omega2+ is only $9.

The Omega2 is an SBC geared for the Internet of Things (IoT) market, billed as the worlds smallest Linux server. It runs a variant of Linux known as OpenWRT, which is most commonly found on embedded devices like routers. Its low power and really tiny at 43mm26mm10mm, its just a little larger than an Arduino Pro Mini.

Dont let that fool you into thinking its not a real computer, however. Its surprisingly powerful for the size, with its MIPS processor running at 580MHz. It supports up to 256MB of RAM, and it can support SD card storage. It supports 802.11b/g/n 2.4GHz WiFi and 10/100M Ethernet, as well as a multitude of other protocols like UART, I2S, I2C, and SPI. It operates at 3.3V, but its docks and expansion boards come with a convenient onboard voltage regulator, which means you can power it with a variety of power supplies without having to worry about blowing it up.

There are just a few differences between the Omega2 and the Omega2+, since they have the same processor. The O2 has 64MB of DDR2 DRAM memory, whereas the O2+ has 128. The O2 has 16MB of onboard flash storage, and the O2+ has 32. Finally, the O2+ has a microSD card slot, which gives you significantly more room for programs. Given the small difference in price, I suggest you pick up the O2+, but all of the projects in this book will work on either model, so if youve already purchased the O2, not to worry.

I would like to interject a small observation here. If you really go back and look at those specs, it is insane how far weve come when it comes to putting computing power into small packages. My first computer was a Commodore VIC-20, which had a whopping 5KB of RAM. Thats less than the size of a standard image thumbnail on the web today, and almost thirteen thousand times smaller than the Omega2s DRAM package.

Quite a few expansion boards and docks are available youre going to need at least one right off the bat, as the Onions headers are at a 2mm pitch instead of the more common 0.1 pitch, which means you cant just plug it into your breadboard. Youll have to use either a dock or a breadboard expansion piece, so my suggestion is to purchase the power dock (). It allows you to power the board and whatever add-ons you happen to have using not just a microUSB cable, but also a 2-pin JST-PH connectorthe standard connector on many lithium-ion (Li-ion) batteries. None of the expansion boards are very expensive, so its worth the time to look around and see whats available when youre shopping for your Onion.