Jon Pearse

By far the easiest way to drive 7-seg displays using an Arduino is to use a MAX7219, for which the Arduino playground has a wealth of information. Each chip can drive up to 8 digits (or a single 8x8 matrix, or 64 individual LEDs if you’re sufficiently masochistic), and can be daisy-chained to drive more. The down-side is that ‘real’ 7219s go for around the £10 mark, but you can get erzatz clones on eBay/AliExpress/etc for substantially cheaper if you don’t mind them occasionally freaking out†. An alternative is the snappily-named Holtek HT16K33, which will commonly drive 16 digits (or a 16x8 matrix, etc) and is substantially cheaper. They’re only available as SO packages, but Adafruit does a really nice breakout board which is a great platform for messing around. (Also, Adafruit has a 4x14-segment LED backpack in various colours, which might just fit this project to a ‘t’). This still isn’t 100% perfect, as the HT16K33 uses I2C, and is therefore limited to wire lengths of about 2 metres… In the interests of balance you can also drive 7-seg displays using shift registers, although I can’t say I’d recommend it. Some people swear by it, I’d personally spend a little extra on the Holtek chip and preserve what remains of my sanity Hope this is helpful, J † as far as cheapy MAX72xx clones go, I’ve used a couple dozen of them across various projects without any real problems that couldn’t be solved with judicious use of decoupling caps. Obviously, YMMV, and you might not want to deploy a cheap clone in a place that’s not easily accessible, just in case…