How to use YL-3 (a 8x7 Segment LED display) with Raspberry Pi
The YL-3 is a 8x7 segment led display modules based on two 3461BS (4x7 segments) and is controlled by two 74HC595. You can buy the YL-3 module online at dx.com. The 74HC595 is a 8-Bit serial shift register which i liked a lot because it was the first time for me to work with it. The principal I learned from this Video by Lewis Loflin and i can pretty much recommend it.
There is sample code for running the YL-3 with Arduino, but I could not find any Raspberry Pi examples. Three hours and a lot of debugging and fighting with the shifting later ... I made up my own example for Raspberry Pi and published it for you on github.
You simply need to wireup the module with the PI. The GPIO pins I used are are shown in the image below:
Hint: If you still using a old Raspberry Pi Rev1, GPIO 27 is called GPIO 21.
Here is how you control a 7 segment: