This is the CP-1252/ASN-128 Navigation Computer Display. The NCD was originally designed for Doppler navigation, but will work in my application. I have reprinted the Analysis of this from my Wordpress Blog (22Apr2011)
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 PinLite lamps, and two LED's. 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 user guide, TM-1-1520-238-10 pages 3-34 through 3-46 on the web.
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BTW I just found TM 11-5841-28-12 which is the Organizational Maintenance Manual for the unit, as a Google book. It has all of the neat error codes and other cool stuff which will be helpful. (6-7-2013) |
In it's dim past it had been converted to a flight sim, and the only things left were: the display, switches, light plate, and lots of wire. Each component, had each of their connection(s) brought out into a header.
From here to the end, has been Redacted 4-1-24
The Plan: It is almost impossible to find a 16-segment display driver, but I found two parts MAX6954 (SPI or QSPI interface), and MAX6955 (I2C interface). Both devices have the same programming model and have an I/O expander that can handle the keyboard. I have chosen to use the I2C interface. I have broken down the NCD into the following sub-units:
- Two MAX6955AAX+MAX6955AAX+:
- one will handle the 4 16-segment displays.
- one will handle the 13 7-segment displays.
- The keyboard will be interfaced via a standard PS2 keyboard encoder that will be harvested from an old PS2 keyboard.
- I will also need 2 bytes of I/O as well:
- 1 byte of output to handle the two rotary switches, via two priority encoders (74LS148).
- 1 byte for both thumb wheel switches (they are encoded to 4-bit BCD).
- And lastly, I need a USB interface to talk back to the IOP (IO Processor)
I also need an embedded microprocessor, the NCD information does not need to be supper fast, as in reality, it is only a dumb terminal, so an Arduino should be able to keep up with everything, if there are speed issues I will most likely switch to a TI Stellaris Launchpad module. The NCD is either taking keystrokes from the pilot or updating the display. In the words of the Outer Limits "There is nothing wrong with your television. Do not attempt to adjust the picture. We are now in control of the transmission. We control the horizontal and the vertical". In the scheme of things, this unit will only be another endpoint on the IOP which is sending the keystrokes or knob turns to the simulation processor. In turn, the NCD in effect listens to the NavGroup via the IOP for the present position, time to go, etc.
Keep Tuned-in, More to Come!
