8 digit 7 segment display module

With this module and a MAX7219 you can work with up to eight 7 segment displays. The activation is taking place serial through three lines (Px.4 = Clk, Px.6 = Load, Px.8 = Data In). Another output line (Px.2 = Data Out) enables an optional extension by another module. The four port pins Px.4 to Px.7 are not needed for activation and have been connected to soldering pins for other possible uses. Nearby 7 segment displays you usually find keys and switches that can be attached here to these vacant soldering pins. For these keys and switches there are to soldering pins with +5 V and GND available.

The Max7219 offers a couple of nice functions: It can i.e. regulate the brightness of the display in 16 steps per software and it isn't bound to only displaying pure numbers through it's integrated BCD to 7 segment decoder. It can be used any possible combination of the segments and you can i.e. also display some letters or 'graphical effects' (this features uses the example program 2 which displays a scrolling font).

Auf course you can use less displays, but the minimum in this setup is 4 pieces (See datasheet of the MAX7219 for further information).

Another tip to the setup: Instead of the 7 segment displays you can solder in two 40 pole wide IC sockets. The 7 segment displays can be plugged into the socket. This way you can easily remove them, exchange them if they are broken or change the number of displays depending on the application.

Data

Schematic

Click on the schematic to open it in full size.

Schematic and Layout

For the schematic and layout plans you need the highly recommended schematic and layout editor EAGLE. A free english version can be downloaded at http://www.cadsoft.de/freeware.htm.

Further downloads