Here at Yoctopuce, we are constantly looking for the best mini-PC to drive our devices. From time to time, we hear about one which seems to be a good candidate, so we buy one and test it, usually in one of our Friday projects. We mentioned most of them in this blog, but here is a short summary.
From our point of view, the ideal mini-PC would be a small computer running Windows, OS X, or Linux; Intel or ARM, we are not hard to please :-) This computer will be permanently up and should be able to drive our devices reliably, a good network connectivity would be a nice bonus. And sure, we would like it to be as cheap as possible, so we can install many of them everywhere in the house. This doesn't look like insane requirements, so let's see what we have so far.
One year ago, the RaspberryPI made a noteworthy apparition. DIYers love it mostly because it is cheap: you can have one for 35 dollars. For that price you will get the board only, no enclosure, no power adapter, no cable. It hosts an ARM processor and runs Linux. Its versatile GPIO port allows you to interface many DIY projects. Unfortunately, one of its weaknesses is the USB port. When a USB 1.1 device, such as a keyboard or a Yoctopuce device is connected, the PI starts to lose USB packets. There is a work-around: you can configure it to work in USB 1.1 mode only. USB 2.0 devices, such as the onboard ethernet adapter, will still work, but will be much slower. Don't expect to draw more than 100mA from the USB ports so you should spare some money for a powered USB hub.
The Raspberry PI, cheap, but far from perfect
Actually, the MK802 is a device meant to be directly plugged into an HDMI TV set. This machine runs Android, but Yoctopuce devices don't work with the Android version installed by default. But it's quite easy to install Linux on it and then Yoctopuce devices will work. The MK802 provides Wifi connectivity only. Unfortunately the Wifi adapter is flawed, a lot of connection losses occur, and when the link is lost, the device seems to a have hard time to recover it. We noticed frequent freezes, mostly due to overheating caused by the unvented enclosure. Anyway, for approximately 50 dollars you will get the device, a power adapter and an HDMI cable.
MK802: poor Wifi connectivity.
MK805 / MiniX
Sold as MK805 or MiniX, depending on seller's mood, the MK805 is supposed to be the MK802 big brother. It features two USB A ports. As the MK802, it's an Android device and you will have to install Linux if you want to drive Yoctopuce devices with it. It works fairly well, except for the power part which is a bit capricious. You may have to plug it several times in a row to make the computer start. The Wifi part works smoothly but there is no wired network. You can have one for approximately 60 dollars.
MK805, a mischievous power-up sequence.
The Beagleboard is an ARM based dev board. It was available long before this ARM-based machine wave. It works with Linux and provide 4 USB ports and, thank God, has a serial console. No need of an HDMI screen to debug connectivity issues on a project, a simple serial cable will suffice. Yoctopuce devices works flawlessly on this board. You need to spend ~$150 to have one, but this is a dev board: no enclosure.
the beagleboard, a fair dev board
Gumstix Waysmall Silverlode
The Silverlode is an ARM-based computer as well. It runs Linux and is sold in a cute little silver enclosure. It features a serial console on one of its USB port. It works well, but there is one issue. The only USB A port works in USB 2.0 mode only, we are still wondering what they where thinking when they chose this design. So if you want to use a keyboard, a mouse, or a Yoctopuce device, you need to insert a USB 2.0 hub between the machine and the devices. This computer will cost you 200 dollars.
Silverlode, USB 2.0 hub mandatory
The Fit-PC is the only Intel based computer in this list. Actually it's an real Compatible-PC, it can run Windows or Linux. It features 4 USB ports, both WiFi and wired network and works very well with Yoctopuce devices. Actually, it is Yoctopuce's favorite computer for small daily tasks which must be accomplished flawlessly. Those machines are so reliable you will forget they even exist. So is this the perfect mini-PC? well not really: don't expect to have one for less than 500 dollars.
FitPC2, great but expensive
No miracle here, if you want reliable hardware, you will have to pay for it. Anyway, we are still hoping to find the ideal mini-PC: both reliable and cheap. If you know of one, don't hesitate to tell us about it.