I have finally made the firmware working to a degree the displays are easy to use.
3-wire serial interface.
At first the display is reset, then it is waiting for a serial data stream.
After all neccessary bits are transfered, the display starts lighting up.
Due to technical reasons, each reset takes about 20 milliseconds.
The serial transfer is relatively independent from the actual used controller.
More information here, including source code to use the displays.
C language is used, so it should be very easy to adapt to Arduino.
It is a synchronous serial transfer.
These displays make circuits much easier and faster to build, as well smaller and cheaper.
Starting at $3.98 for 3 digits!
More info here: http://pic.hitechworld.org/serial_led.html
If requested, I have a micro Arduino here, and could adapt the C source to this platform.
It is however not dificult to do I think.
These displays are available now and have been tested.
Developement time was about 2 years.
Indeed any multiplexed LED diplay can be used with upto 12 pins.
Not limited to 7segment displays!
The displays work best at 3V however also can be used at 5 volts.
It is either possible to change the firmware a little so they are less bright,
or use them with high brightness.
I will accept requests to code the data tables for any 7segment display,
preferably if you buy more than one display.
All I need is the datasheet and a sample if possible. Or information where to buy a sample display.
I have available here 4digit displays and 3digit displays, but can offer other colors than red if there is demand.