I’ve christened this version of the Arduino “CheapDuino” – I do hope someone hasn’t registered the name…
The idea here was to see how cheaply I could put one of these together for and find out how easy or otherwise it might be. The “Veroboard” was the most expensive and that’s because Maplins make an obscene mark-up and I was desperate. I’ve a load more coming from China but I could not wait (usually takes around 2 weeks).
What you see above (excluding the green Ethernet board on the left which is yet to be mounted) is a working Micro. I’ve put a few of these together and this is pretty much the minimum that is practical to use. Firstly, you can never have enough ground connections so I’ve put 3 of those, 3 of the 5v connections – and a 3.5v (approx) out as many peripherals run on 3v3 or thereabouts (like the Ethernet board). There’s an input pin over on the right. I had to cheat a little – there are 3 wires and one decoupling cap underneath (for the 3v5 output). If I’d had SLIGHTLY wider board I could have gotten the lot on the top. The board came with split track which made life easy – I had to cut only 3 tracks underneath.
This board ( call it Arduino but in fact all it has in common is the same BOOT code and compatibility) when it’s done will form the controller part of my Internet Thermostat (the other part has a similar micro and an LCD display but draws power from the main board, fed only by a 4-core telephone lead). As to costs, you’re probably looking at £8 tops if you avoid Maplin for the board… the Atmel 328 chip was the most expensive item, £2.99 un-programmed and I’ve put together a simple programmer which simply fastens to the 60way connector on the (unpowered board) to flash the chip – once done all it needs is a 9v plug-in-the-wall and an Ethernet connection.
Things have come along – but only recently – since I used to play with PIC chips many years ago (I still have an award stuck on the wall) it seems people are still messing with those things – and until recently the libraries of code for the Atmel were pretty dire but today, with a little R&D it’s quite possible to perform miracles with these – talking to the Internet is one of them – add in the cost of the Ethernet board from China and you’re still not much over £12 – which puts this in a different ballpark to the likes of the Raspberry Pi (if Farnell ever get their act together).
This little fellow has some work to do before it ends up in my main project – I need to test the WATCHDOG and several other things to see how reliable they are – but it’s nice to know that you can knock something like this up in maybe an hour if need be at very low cost.
For reference, the unit has 32K of Program memory, 2K of RAM, 1K of EEPROM and host of timers, A/D convertors, hardware interrupts etc all thankfully made pretty easy to use thanks to the freely available Arduino IDE. Oh, and 13 digital lines and 6 analog inputs….