BendixKing FPI 3501B System FPD 500 - Manual (Page 7)

FPD 500 FLAT PANEL DISPLAY SYSTEM
The Graphics Processor communicates with the IP via a host inter-
face and dual port memory. The GP executes its own BIT indepen-
dent of the IP to determine its own health status. The GP also acts
as an independent monitor of the IP and the IP independently moni-
tors the GP. If the GP detects an IP failure, it shall independently dis-
play to the flight crew a fail status message “DU FAIL”.
Integrity of displayed data is verified using two separate functions.
First, random pixels in unused portions of the LCD are driven by the
Graphics Engine and the pixel location and color are wrapped back
around and compared with the bit map of the display. Miscompares
result in displaying “DU FAIL”. Second, the IP selects a portion of the
display for monitoring by instructing the GP to return a small window
of pixels. In the case where pitch data is monitored the horizon line is
captured and the pixel data reconstituted by the IP to verify that the
correct pitch attitude was displayed. This monitoring provides an end-
to-end wrap around verification of displayed critical data.
1.3 ADI/HSI FUNCTION MONITORING
Critical input data consisting of the synchro inputs of pitch, roll, and
heading are monitored for the following conditions and a failure flag is
displayed if any of these conditions exists:
1. Invalid display data or displaying misleading data.
2. Synchro input data outside “reasonable” window.
3. External data valid signal indicates "invalid".
All other input data with an associated valid signal is not used when
the data valid signal indicates “invalid”. Data in this category
includes: Course deviation, glideslope deviation, localizer deviation,
radio altitude, speed command, rate of turn, and INS/DME distance.
Introduction
1-3
Rev. 0
Jan/97
A