The TPRO-PC104 performs timing and synchronization functions referenced to an input timecode signal. The board synchronizes its on-board clock to the incoming timecode. The on-board clock’s time is also provided as an IRIG-B output. Other features include a time-tag TTL input, a programmable “heartbeat” pulse or squarewave output (with interrupt capability), and a programmable “match” start/stop time output (with interrupt capability).
The board continues to increment time (“freewheel”) in the absence of an input timecode. Thus, the board can be used as an IRIG-B timecode generator by setting the initial time via the bus.The input timecode format (IRIG-B, IRIG-A or NASA36) is automatically detected. Synchronization to the input timecode is also automatic and can be enabled/disabled via the ISA bus. A propagation delay offset may be specified to compensate for cable delays.
The timecode input is an amplitude modulated sine wave. An automatic gain control (AGC) circuit permits a wide range of input amplitudes. The timecode input is differential; the board does not reference this signal to ground. A single-ended input (referenced to ground) is also acceptable.
The board can be ordered with option “–M” to synchronize to a one-pulse-per-second (1 PPS) input instead of an incoming timecode. In this case, the initial time is programmed via the bus, and the board begins counting on the next 1 PPS pulse.
The board occupies 16 consecutive addresses in I/O (not memory) space. Jumpers on the board allow for selection of base address and the interrupt level. All board functions can be used without interrupts, if desired.
All board functions can be accessed using 8-bit transfers. In addition, the time can be read with four 16-bit transfers. Binary-coded decimal (BCD) format is used for setting and reading the time.
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TPRO- 104 - datasheet, including full product specifications (149kb PDF)