Spectracom TSync-PCIe, User Manual

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6.5 General Purpose Input/Output
The TSync-PCIe board has four general purpose input (GPIO) pins and four general purpose
output (GPIO) pins. The General I/O subsystem provides a mechanism to generate or time
stamp external events, to match times and generate a signal, to create Heartbeat pulses, or to
create square wave clock signals synchronous to the internal timing system clock and to the
1PPS signal from the input reference.
6.5.1 Programmable Inputs
The General I/O input pins support user selection for detection of rising edge or falling edge
input events. These inputs, when triggered, are used to time-tag the input edge-detected events.
They support a time between input events of 50 nsec and an overall rate of more than 10,000
time stamps per second. Time stamps are maintained in a FIFO on the board that can store up
to 512 unique time stamps among all input pins.
6.5.2 Programmable Outputs
The user may select the operational mode of the General I/O outputs pins, setting them to gen
eric output pins, square wave generation, and match time events.
The General I/O outputs, when configured as generic output pins, can be controlled and
changed at the user’s discretion.
The General I/O output can be programmed as a square wave synchronized to the 1PPS.
When used to output a square wave, the General I/O has a programmable period range of
100 nsec to 1 sec (10 MHz to 1 Hz) in 5 nsec steps and a programmable pulse width of
10 nsec to 999,999,990 nsec in 5 nsec steps (polarity is programmable).
The General I/O is configurable as a Match Time Event pin, which will activate at a preset time
and become inactive at another preset time. The Match Time Event provides two user settable
times to make the General I/O pin active and inactive. The Match Time Event configured Gen
eral I/O pin has a programmable edge, allowing the selection of Low to High or High to
Low.s
The General I/O output signals timing are accurate relative to the Input reference’s 1PPS signal
to within ±50 nsec. The General I/O output has a programmable offset, which ranges from -
500 msec to +500 msec in 5 nsec steps.
6.6 System Status
The TSync-PCIe board maintains status information. It logs error and informational messages
while operational. System status information (synchronization status, holdover status, freerun
status, and total system uptime) are available to the user. In addition, alarm conditions and time
stamps for the alarms are available for conditions including synchronization, holdover, fre
quency errors, PPS specification errors, reference changes, and system errors.
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Instruction Manual XYZ Rev. R
6.5 General Purpose Input/Output