Navigation Computer Display
This is my CP-1252/ASN-128 Navigation Computer Display. 
The NCD was originally designed for Doppler navigation, but will work in my application.
The Analysis The NCD is comprised of 4 groups: Display, Keyboard, Rotary Switches, and Thumb Wheel Switches. The Display is comprised of 4 16-segment and 13 7-segment Pin Lite lamps, and two LEDs. The keyboard is comprised of a 10 key number pad and 4 special keys, it also encodes A-Z. There are two rotary switches, and two thumb wheel switches as well. I also found a users guide, TM-1-1520-238-10 pages 3-34/3-46 on the web. This NCD had been gutted in its dim past and converted to a flight sim and the only thing left was the display, switches, light plate. Lots, and lots of wire, each component, had each of their connection brought out to a wire in a header.
The Plan It is almost imposable to find a 16-segment display driver, but I really found two parts MAX6954 (SPI or QSPI interface), and MAX6955 (I2C interface). Both interfaces have the same programing model and have a I/O expander which could handle the keyboard. I have broken down the NCD into the following sub-units:
- One will handle the 7-segment devices
- The keyboard will be interfaced via a standard ps2 keyboard encoder
- I need to handle the 4 16-segment devices.
- I will also need 2 bytes of output to handle the two rotary switches, and 1 byte for both thumb wheel switch (they are encoded to 4 bit BCD).
- I will also need to listen on Ethernet UDP for nav frames.
The NCD will talk to the Nav Computer via IP. I will write the software in C, and I will be using non-blocking I/O with UNIX signal().
UPDATED: Multi-Function Display (MFD) System – Part 1
Phoenix 2000 Flight Simulator 
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