In this review we examine a kit from the people at Evil Mad Scientist Laboratories – their Diavolino. In English this means “little devil”. This little devil is a low-cost Arduino Duemilanove compatible board – with a few twists.
This is sold as a bare-bones kit, so you really need to plan ahead with regards to how you want to use it. It does not include a USB interface, nor power socket, header sockets, IC socket, nor a voltage regulator. This may sound like a bad thing – but it is not 🙂 This kit is perfect for those who wish to make a permanent project using the Arduino system, without spending the extra on a whole board, and without the hassles of making your own barebones PCB version. So let’s have a look… the kit ships in a nice reusable anti-static bag:
and upon turfing out the contents, one receives:
Which is just enough to have a basic setup. The instructions on their web site mention the inclusion of some zero-ohm resistors to be used as jumpers, but these were not included. However that is a non-issue, some resistor lead clippings will do the job. EML have gone to a lot of trouble with the printed-circuit board. It certainly is different to the normal green or blue ones out there. It is very well detailed with component position labels, and all components are through-hole. The other side of the board is also printed this way:
There is also a nice instruction laminated card included in the bag which has enough information to get your started. Furthermore, there is an excellent instruction manual available for download here (10 MB). Finally, this is an open-source hardware product, so the designers have also made available the gEDA CAD files.
Now for assembly. Normally I would photograph each step, however the instructions available for download are so good, I won’t need to 🙂 Eleven out of ten for the instructions. Soldering it together is quite easy, however I did supply my own IC socket – I am just not a fan of soldering expensive parts (I get the shakes sometimes), however if you are confident, go for it.
Before deciding to permanently solder in that microcontroller, you will first need to take into account how you will be programming it. As the board does not support the usual native USB interfacing, you can’t just plug in the cable like a normal board. The Diavolino does have an interface for a TTL-level cable – so if you have (for example) a USB FTDI cable, you can program it via the USB port. But considering an FTDI cable is around $20, you might as well just buy a normal board like an Eleven instead. It only took around fifteen minutes to get to this stage:
For my personal use as another bench-based board (that sounds a little odd…) I will power it from the FTDI cable, so a link is required behind the TTL input pins – as well as adding the 6-pin and 8-pin header sockets. The easiest way to solder those in is to turn the whole thing upside down and plug it on top of an existing shield, as such:
However if you don’t want to buy an FTDI cable – and you already have another Duemilanove board, the cheapest way to program the microcontroller is to just insert it into a Duemilanove-type board, upload the sketch, then drop the chip into the Diavolino.
You also need to decide on how to power the board. If you supply 4.5~5.5V, all you need is to feed in the power wires. If you are going to use more than 7V, you will need a 78L05 power regulator, 10uF electrolytic capacitor and a DC socket to use a plug-pack if necessary (see the instructions). However, a 78L05 can only supply 100 mA of current (see the data sheet.pdf), so you won’t be able to use some products like a MAX7219 LED driver and many LEDs.
Unfortunately there isn’t enough space for a TO-220 sized 7805 1 amp regulator, so you will need to introduce 5V using an external supply hard-wired into the board if you need more than 100mA of current. Or you can power it from the USB FTDI cable for desktop use.
So there you have it – another successful kit build. This was an interesting alternative to the Duemilanove, and a great solution for a permanent project, or for someone who wants another board on the cheap. If you can work with the power supply current restrictions, all is well. So get one or more, have fun with it, and give one to someone else to get them cooking as well.
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