The
6508 Plan Position Indicator Video Interface is a VMEbus-compatible 6u board designed to output video and video trigger signals to be used for the Bendix PPI-1T Weather Radar Indicator.
Key Features:
- VMEbus 32-bit Slave access read/write to Video Interface board
- Output trigger rate of 200 HZ generated on board - no need for operating system to stimulate trigger
- Video output capable of delivering an analog signal representing 256 samples or Range Bins at the various range settings
- Two banks of memory providing simultaneous write from VMEbus and read to video output
- Read/Write Control Register used to set range and gain of video output
- Read only Status register used to check overflow, empty flags from the memory, and indicate to host which memory bank is currently in use
- Test feature allows user to read memory back onto the VMEbus
- This Product was designed, built, and in use for the Bendix PPI-1T Weather Radar Display
Functional Description:
The PPI-1T Video Interface is a memory-mapped VME 6u multilayer slave board communicating to the host processor using the Extended Non-Privileged Data Access mode. The board has a fixed base address that must be used to address all functions.
A reset sent to the board initializes all functions, and a read of the status register verifies that the on-board FIFO's are empty. Instructions are then downloaded to the Control Register indicating the Range Scale and Video Output Gain information. Next, 64 Longwords of data representing 256 bytes of the video data are sent to FIFO Bank #0 and the Status Register read to verify that the FIFO is full. The host downloads the next 256 bytes of data to FIFO bank #1 and again checks the Status Register for FIFO full. Test reads of the FIFO's may occur to insure data integrity at this time.
The host sends the Start Fifo Bank #0 instruction to start reading 256 bytes of the Bank #0 FIFO data. This instruction causes data to be read out of the FIFO at a rate determined by the Range Scale setting in the Control Register. The data is sent to a Digital-to-Analog Converter (DAC) and sent out to the display along with a 200HZ trigger pulse. The gain of the output video signal may be adjusted by the host, as necessary.
The Video Interface board will continue to re-transmit the data out on Bank #0 until the host tells it otherwise. To switch banks, the host reads the Status Register to determine which bank is currently in use (Bank #0 in this case) and will send an instruction to the Video Board to Start FIFO Bank #1. Bank #1 will be read only after Bank #0 is empty and on the next 5mSec (200HZ) rate. New data may now be downloaded to Bank #0 and the process is repeated for FIFO Bank #1.
Physical Description:
The PPI-1T Video Interface Board is implemented on a double height d form factor printed circuit board. The board interfaces with the VMEbus back plane through a DIN Type "C" connector that conforms with DIN requirement 41612. On the front edge of the board, a 9-pin subminiature "D" type male connector is used for +15VDC and -15 VDC power and two BNC type connectors used for the video and video trigger signals.
Specifications:
VMEbus Slave: D32 : A32
VMEbus Data Transfer: 32 bit only
VMEbus Addressing: 32-bit Extended I/O addressing (non-privileged)
Video Output: Video is 0 to 4.5V +- 0.5V
J3 - BNC Type Connector
Video Trigger Output: Trigger is 200HZ; 0 to 13.0V +- 2.0V
J7 - BNC Type Connector
Temperature Range: 0 to 45 C operating,
-20 to 85 C storage
Relative Humidity Range: 20% to 80% non-condensing
Cooling: Convection
Dimensions: Double Eurocard
166mm x 233.4mm x 12mm
Power Requirements: +5VDC at 2.0 Amps
+15VDC at 100mA @ J6-1
-15VDC at 100mA @ J6-5
External +15VDC and -15VDC power supplies are required to be used on J6-1 and J6-5, respectively. J6-3 and J6-7 are ground. J6 is a 9-pin "D" type subminiature male connector.
