1.3. Functional Description
1.3.4. Time Coincidence Strobe Output
The TFP provides one Time Coincidence Strobe Output signal. The Strobe output is like an alarm that
is activated at some preprogrammed time. The Strobe time can be set from days through micro-
seconds. The duration of the Strobe pulse is one microsecond. Two modes of operation are sup-
ported. In one mode (STRMODE=0), both the major and minor times are used to generate the Strobe.
In the other mode (STRMODE=1), only the minor time is used to generate the Strobe output, pro-
ducing an output pulse once each second. The Strobe is programmed using the CONTROL Register
as described in "CONTROL Register (0x10)" on page 28.
1.3.5. PCI(e) Interrupts
The TFP supports the seven interrupt sources listed in Table 1. Each interrupt source can be individ-
ually masked off. Use the MASK register to mask on or off each interrupt source. Each interrupt
source sets a corresponding bit in the INTSTAT register when the interrupt occurs. When servicing a
TFP interrupt, the Interrupt Service Routine (ISR) in the driver reads the INTSTAT register in order to
determine the interrupt source(s) requesting service.
Table 1: TFP Interrupt Sources
Int Interrupt Source
0
Signal transition on Event Input has occurred (edge selected by EVSENSE)
1
PPO edge has occurred (edge selected by EVSENSE)
2
Time Coincident Strobe output rising edge has occurred
3
One second epoch (1 PPS output) rising edge has occurred
4
GPS data packet is available (bc637pci-V2 only)
5
Signal transition on Event2 Input has occurred
6
Signal transition on Event3 Input has occurred
1.3.6. Additional Timing Output Signals
The 1 PPS output is a 60 μsec wide pulse with the rising edge occurring at each 1 second epoch.
A Time Code output signal is available in both AM and DCLS forms simultaneously.
An output frequency of 1 MHz, 5 MHz, or 10 MHz (HCMOS) is selectable.
1.3.7. AM Time Code Calibration
The following AM Time Code calibration procedure is used to adjust the phase of the Time and
Frequency Processor when operating in Time Code Mode and using an AM (amplitude modulated)
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