CHAPTER ONE
1-2
bc620/627AT Time and Frequency Processor
Symmetricom, Inc.
•
Provides an output clock synchronized to the selected reference; programmable 1, 5, or 10
MHz TTL.
•
All modes of operation are supplemented by flywheel operation (i.e. if synchronization
source is lost the TFP will continue to function at the last known reference rate).
•
Generates synchronized IRIG B time code. Modulated and DC level shift formats are
produced simultaneously.
•
Programmable frequency output (periodics) is provided. Pulse rates from 2.3 MHz to 2.5
MHz are supported.
•
A time coincidence strobe output is provided. Programmable from days through
milliseconds. This strobe also has an “each second” mode programmable to milliseconds.
•
Five maskable interrupt sources are supported. IRQ levels 3-7, 9-12, 14, and 15 can be
selected via jumper JP1.
Interrupt #
Source of Interrupt
0
External event input has occurred.
1
A periodic output has occurred.
2
The time coincidence strobe has occurred.
3
A one second epoch (1pps output) has occurred.
4
An output FIFO data packet is available.
1.2 PHYSICAL AND FUNCTIONAL OVERVIEW
The bc620/627AT is a half length PC AT I/O expansion bus board. Operation is controlled via
two 16 byte pages of 8 bit registers written and read by the host via the PCbus. The bc620/627
AT occupies 16 bytes in the AT I/O address space. The I/O signals are accessible via two 15 pin
“D” connectors mounted on the rear panel. The bc620/627 AT is shown in Figure 1-1.
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