I’ve been playing around with LED scrolling signs for a while now and have been looking for an affordable sign to use for a project. Some LED signs are really expensive but I’ve recently come across this one from Embedded Adventures:
It’s a 80×8 display with three colours – Red Green, and Red/Green mixed to produce Orange. It measures about 35x4cm in size so is ideal for something eye catching.
Best part is that it’s available for just £20 from the Embeded Adventures website. It’s ready assembled so you don’t have to get out your soldering iron.
To connect to your Pi’s GPIO follow the instructions on this page – which includes a handy python script by Pete Goss. For the wiring guide note that the numbers refer to the number of the pins as you count across, not the GPIO number. This is also for the Rev 2 board model A or B (if you have mounting holes, your Pi is fine).
|Raspberry Pi pin number (GPIO pin label)||LDP-8008 pin number (label)|
|3 (GPIO 2)||2 (A row address)|
|5 (GPIO 3)||4 (B row address)|
|6 (GND)||5 (GND)|
|7 (GPIO 4)||6 (C row address)|
|8 (GPIO 14)||7 (EN enable display)|
|10 (GPIO 15)||8 (D row address)|
|11 (GPIO 17)||9 (red LED)|
|12 (GPIO 18)||10 (green LED)|
|13 (GPIO 27)||14 (latch)|
|15 (GPIO 22)||16 (shift)|
There’s a slight errata on the page as you have to type:
sudo python scroll “Raspberry Pi” 1
to get it to work.
I found that it will work powered just from the GPIO of the Pi, but if you need a brighter display you can just hook up a 5 volt power supply (e.g. a spare USB charger) to the central pins – this doesn’t need to be connected to anything else. The lower pin (with the printed text on the back the right way up) is ground – I used the cable off a novelty LED light from Poundland.
For the cable you can use jumpers or for something more permanent I found this Maplin GPIO breakout board available for £3.49 to be ideal. The LDP8008 comes supplied with a ribbon cable you can use.
Here’s a closeup of my cable – by cutting the grey cable different lengths you can make it quite neat. I also added a plastic cover cut from a spare toolbox divider.
and the cable attached to the GPIO on the Raspberry Pi (make sure you get pin 0 on the right side!)
Note that in my case, the labels on the Maplin GPIO breakout board were incorrect – make sure you double check everything before plugging it into your PI so you don’t break it!I also found the display a little sluggish if anything else is running.
For extra neatness I mounted the whole setup in a box frame – the one I used came from Wilkinson’s and was £6.