Altera cyclone V Technical Reference page 1286

cv_5v4
2016.10.28
low, then the new command overwrites the previous command and the EMAC may generate only 1
extended pulse.
Generating a Pulse Train on PPS
To generate a pulse train on PPS:
1. Program 11 or 10 (for an interrupt) in Bits [6:5], TRGTMODSEL, of Register 459 (PPS Control
Register) to instruct the MAC to use the Target Time registers (register 455 and 456) for the start time
of the PPS signal output.
2. Program the start time value in the Target Time registers (register 455 and 456).
3. Program the interval value between the train of pulses on the PPS signal output in Register 473 (PPS0
Width Register).
4. Program the width of the PPS signal output in Register 473 (PPS0 Width Register).
5. Program Bits[3:0], PPSCMD, of Register 459 (PPS Control Register) to 0010 to instruct the MAC to
generate a train of pulses on the PPS signal output with the start time programmed in the Target Time
registers (register 455 and 456). By default, the PPS pulse train is free-running unless stopped by 'STOP
Pulse train at time' or 'STOP Pulse Train immediately' commands.
6. Program the stop value in the Target Time registers (register 455 and 456). Ensure that Bit 31
(TSTRBUSY) of Register 456 (Target Time Nanoseconds Register) is clear before programming the
Target Time registers (register 455 and 456) again.
7. Program the PPSCMD field (bit 3:0) of Register 459 (PPS Control Register) to 0100 to stop the train of
pulses on the PPS signal output after the programmed stop time specified in step
elapses.
You can stop the pulse train at any time by programming 0101 in the PPSCMD field. Similarly, you can
cancel the Stop Pulse train command (given in step
PPSCMD field before the time (programmed in step
train generation by programming 0011 in the PPSCMD field before the programmed start time (in step
on page 1-71) elapses.
Generating an Interrupt without Affecting the PPS
Bits [6:5], TRGTMODSEL, of Register 459 (PPS Control Register) enable you to program the Target Time
registers (register 455 and 456) to do any one of the following: †
• Generate only interrupts. †
• Generate interrupts and the PPS start and stop time. †
• Generate only PPS start and stop time. †
To program the Target Time registers (register 455 and 456) to generate only interrupt events: †
1. Program 00 (for interrupt) in Bits [6:5], TRGTMODSEL, of Register 459 (PPS Control Register) to
instruct the MAC to use the Target Time registers (register 455 and 456) for the target time interrupt. †
2. Program a target time value in the Target Time registers (register 455 and 456) to instruct the MAC to
generate an interrupt when the target time elapses. If Bits [6:5], TRGTMODSEL, are changed (for
Ethernet Media Access Controller
Send Feedback
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Generating a Pulse Train on PPS
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7
on page 1-71) by programming 0110 in the
6
on page 1-71) elapses. You can cancel the pulse
17-71
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6
on page 1-71
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