Single Board Computers

Little computers on a small circuit board. Some with video, some with USB for keyboards and mouses, all with I/O for controlling stuff, and that's right down my alley. They all run Linux, and they are intended for hobbyists (or professional product developers) with skills ranging from schoolkid to embedded systems designers.

My first exposure to computer modules was a Tomahawk engineering test station with a Micromint Domino, which had a serial terminal connection and was programmed in BASIC. A few years later, and it was a PC/104 computer which ran DOS and I was programming it in Borland C to control a storage tower. All these new little SBCs are more a general-purpose computer than the Domino and smaller and faster than a PC/104, and cheaper than either.

I got a Raspberry Pi to play with about a year after it had appeared commercially - the price was just too good to pass up. Then over the last two years there has been a barrage of Kickstarter and Indiegogo projects for either really inexpensive Pi competitors or larger boards that are still pretty reasonably priced. Some of them were irresistable.

Here's the set of boards I've got to play with. Upper left, in an acrylic after-market case, is the Raspberry Pi 1 Model B. Next to it is the largest board, the Creator Ci40. Bottom right is the Onion Omega2. Next to it is the C.H.I.P. Finally is the tiny VoCore2 in a docking station and a case.

SBC Menagerie

Raspberry Pi

RasbPi has a tremendous culture and a portfolio of products. Wikipedia has a good comparison of the models. RasbPi is Open Hardware - which has encouraged the appearance of knockoffs like Orange Pi and Banana Pi (RasbPi is originally a British development, but Banana and Orange are Chinese) which are probably a bit more capable but (being Chinese) harder to get hold of.

Pluses: Ethernet, HDMI video native, cheapo Composite video

Minuses: Not a lot of I/O, and all as individual discretes. I'm also not real sure of using a MicroSD card as the main memory, although that does ease loading operating systems and such. Having a MicroSD increases fragility and the likelihood of loosing connection in an embedded application. The card also juts out from the edge of the board a considerable distance.

Rasb Pi in case side 1I wasn't exactly an early adopter, so I held out for the "B" model. This is a RasbPi 1 Model B in a cutesy acrylic case from Adafruit. The cable is a "Cobbler" and brings the I/O header out to a connector that can be plugged into a solderless breadboard. On this end is the Ethernet RJ11 and the two "real" USB ports. On the side is the 1/8" audio jack and the RCA connector for composite video.

Rasb Pi in case side 2The other end has the "fake" mini-USB for power and the MicroSD card sticking way out even beyond the box. On the side is the HDMI connector. Either composite video or HDMI video may be activated; they don't both work at the same time.

Rasb Pi out of caseOutside of the case, you can see the uncomfortable arrangement of the connectors. There's just no nice way to design a daughter board.

In fairness, the Pi 1 Model B is obsolete. The flagship at this time is the Pi 3 Model B, which has a much nicer footprint for daughter boards - which are called "HATs", rather like Arduino boards are "shields" and LaunchPad boards are "capes". Also has built-in Bluetooth and WiFi. For the same $35 price. But I've already got this one, and I need to play with my toys before I retire obsolete ones and get the current model.

NextThing C.H.I.P.

I'm not positive, but I think the C.H.I.P. started the really cheap SBC trend. Now, the RasbPi Zero is essentially the same price as the $9 C.H.I.P. $9!!

NextThing is working real hard to build up a community. The momentum is growing.

Pluses: Beautiful I/O arrangement, perfect for daughter boards, of which there are already several available (called "DIPs"). Small. On-chip solid-state drive. LOTS of I/O - most is dedicated for a OLED display, but if a display isn't needed, then ALL those pins can be GPIO. I'm pretty sure with some effort they can be read or set in banks as well as individual discretes. On-chip WiFi, Bluetooth, and it's Open Hardware.

Minuses: No built-in hi-def video or Ethernet. Daughter boards are required for these purposes. For embedded control purposes, maybe this isn't so bad.

C.H.I.P. box set What you get for $9. Includes the breakout cable for stereo audio and composite video. The SBC has a plastic backing to serve as a "case".

C.H.I.P. USB endThe business end with the Type B USB, three-way 1/8" jack for audio and video, and the mini-USB for power (and for a USB serial console connection with a host). Dig the pin labeling on the 0.1" female header nests.

C.H.I.P. battery connector endThe other end has a connector for a lithium battery.

At $9 and a great form-factor, I think C.H.I.P. may become my preferred platform. There is a "Pro" version for $16 that does not have the mating pins or appear to be expansion compatible with the C.H.I.P. BUT... the basic C.H.I.P. is not available at the moment (May 2017), as they are re-laying it out for their own upgraded GR8 processor. Which is already on the Pro device. But I think the non-availability is more of a supply-chain problem, as (per the Forum) new C.H.I.P.s are getting received and are filling backorders. So maybe things will catch up sometime.

PocketC.H.I.P.

PocketCHIP, front viewThis "hand terminal" was developed along with the controller itself. Natively, the incorporated C.H.I.P. has a GUI (not obviously X), a music player, and an 8-bit game emulator. This appears to be the primary objective of PocketC.H.I.P.; the development of 8-bit games. I tried a few, couldn't figure them out, didn't work real hard. The snap-button keyboard is rather cumbersome. Note the cute feature for sticking a pencil through a hex-shaped hole for a stand, and the triangular hole at the top for a lanyard.

PocketCHIP, rear viewThe C.H.I.P. just plugs into the back. All the I/O is available as pads along the top of the terminal, but I don't get that, as most of them are already being used for the LED display. The USB and audio connectors are available while plugged in.

Interestingly, while the C.H.I.P. itself is not for sale at the moment (apparently because backorders are being filled), the PocketC.H.I.P. of course incorporates a C.H.I.P., and PocketC.H.I.P. is for sale - and being heavily promoted on their front page and the blog.

Onion Omega

Let's root for the underdog - The Omega2 has a MIPS processor! It also has built-in WiFi. And it's even cheaper than the C.H.I.P. at $6! The 2Plus is $9, for twice as much memory and a MicroSD. It does NOT appear to be Open Hardware.

What I got for $64 in their Indiegogo project offer: Two Omega2s, one Omega2Plus, choice of three expansions (in this case, Ethernet, OLED, and Servo), a standalone dock (0.1" female headers, USB, some switches) and a breadboard dock (0.1" by 0.3" pins to plug into a solderless breadboard). And a sticker.

Onion Omega Kit

Pluses: It's real small. Cheap, too.

No built-in Ethernet or Bluetooth; like the C.H.I.P., these are available via expansion boards. Doesn't look like the expansion boards plug into the Omega2 itself, but rather via a dock. Worst, though, the pins are on 2mm centers, not a nice English 0.1-inch arrangement. Thus, unless it is being put in an embedded circuit board that provides the same access, it isn't a $6 device, it's a $21 device - adding the $15 dock.

Also, there's no video at all, and no keyboard/mouse; it's unapologetically headless. And, unlike the C.H.I.P., it appears there's no USB serial console connection - you connect to it over WiFi and use a SSH shell. But again, for embedded control, that's okay.

Onion OmegaPretty darn small.

Creator Ci40

I had been watching Creator (by Imagination Technologies) for some time, mostly because it uses the underdog MIPS processor. Then I saw a Kickstarter project to kick off the new Ci40 in a kit, and the price was pretty good. Now that I look at it closer, it seems the Ci40 board itself is intended to be a IoT "hub", and talks with remote gadgets via 6LoWPAN radio. The Ci40 seems to be available ongoing only in a kit, from Mouser, for $156. This is really not an embedded control processor. And it shows.

Ci40 CreatorBig board. On-board Ethernet, WiFi, Bluetooth, and USB, so again, serial console interface. It has a Raspberry Pi compatible I/O connector!

Ci40 Creator with modulesThe interesting thing, though, is the use of Click boards from MikroElektronika - and there is a wealth of options. The Ci40 itself has two Click ports, and the 6LoWPAN "Clicker" board (of which the kit has two) has a Click port. Here is a Relay Click board, next to the Ci40 and the Clicker.

VoCore2

I got rooked with this one - the Kickstarter proposed this would be a $4 device. On their product page, where they are available for sale, it's $18. The I/O is not convenient. No video, just the serial console, either via TTL or USB or WiFi SSH.

Pluses: It's Real Small. Which would be great if it were cheap. But it's not.

Minuses: You really can't get at the I/O without soldering it to something. Even the "dock" VoCore has does not break out the I/O. And it's not cheap.

Vocore Kit, Ethernet endWhat I got in the Kickstarter offering. From the front, the Ethernet connection and audio jack.

Vocore Kit, USB endFrom the back, the micro USB connector for power and serial comms, the larger USB for applications, and a slot for a MicroSD card.

Vocore in Dock, UncasedWith some delicate prying, the case opens and the assembly can be removed. It's really not a "dock", but an assembly. As a matter of fact, the VoCore web page calls this an "Ultimate" - for $45. Not cheap.

Vocore in Dock, Close-upClose up showing the construction. Not a "dock". There are four I/O pins at the lower corner, and four more next to the audio jack - and you can't get at them when it's installed in the case. Unless you want to cut slots in your $45 "Ultimate".

I'll play with it. But it comes in third or fourth in the current race.


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