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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:

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

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