IDT Clocking, Reset, and Initialization
Clock Operation
PES16NT2 User Manual
2 - 8
April 15, 2008
Notes
Figure 2.5 Fundamental Reset in Transparent Mode with Serial EEPROM initialization
Hot Reset
A hot reset may be initiated globally to the entire device, globally to downstream ports or locally to down-
stream port(s).
The PES16NT2 provides a reset output signal for each downstream port implemented as a GPIO alter-
nate function. The downstream port C reset output (PECRSTN) signal is an alternate function of GPIO[1].
When a hot reset occurs, the corresponding port reset output is asserted
1
for at least 250 ns. When a global
hot reset occurs, all of the GPIO pins default to GPIO inputs. Therefore, the downstream port resets are tri-
stated. A system designer should use a pull-down on these signals if they are used as reset outputs.
When the switch is configured for non-transparent operation, a hot reset may be initiated on the external
side of the non-transparent bridge. Fundamental and hot resets in non-transparent mode are described in
the Non-Transparent Mode Reset section.
Globally Initiated Hot Reset To Entire Device
A hot reset is initiated globally to the entire device when any of the following conditions occur.
–
Reception of TS1 ordered-sets on the upstream port indicating a hot reset.
–
Data link layer of the upstream port transitions to the DL_Down state.
Hot reset is only propagated downstream. TS1 ordered-sets indicating a hot reset received on a down-
stream port do not result in a hot reset of the downstream port or any function inside the switch.
When a globally initiated hot reset occurs, all of the logic associated with the transparent bridges, stacks
and the switch core are reset except for the PLLs, SerDes, master SMBus interface, slave SMBus interface,
and some registers. Regardless of the switch operating mode, a hot-reset does not result in reloading of the
serial EEPROM. The value of register fields denoted as “sticky” or as Read and Write when Unlocked (i.e.,
RWL) are preserved in all ports across a hot-reset. All other register fields in all ports are reset to their initial
values.
When a hot reset is initiated globally, each downstream port sends a hot-reset message to its link
partner prior to being reset.
1.
Since the PExRSTN signals are active low, the signal should be driven low for 250ns.
REFCLK
Vdd
PERSTN
SerDes
Master SMBus
Slave SMBus
RSTHALT
Tpvperl
PLL Reset and Lock CDR Reset & Lock
Ready for Normal Operation
Ready
Ready
Serial EEPROM Initialization
1.01 ms
up to 12 µs
Link Training
Quasi Reset Mode
Ready for Normal Operation
< 100 ms
Boot vector sampled
Device ready for
normal operation
< 1 sec
Stacks
Notes:
1) Reference Clock (REFCLK) not shown to scale.
2) The PES16NT2 requires a minimum time for Tperst-clk of 1µs. The PESPES16NT2 requires a minimum time for Tpvperl of 1ms.
3) In a system, the values of Tpvperl and Tperst-clk depend on the mechanical form factor in which the PESPES16NT2 is used. For example,
the PCIe Card Electromechanical Specification, Revision 2.0, specifies minimum values of Tperst-clk=100µs and Tpvperl=100ms.
Содержание 89HPES16NT2
Страница 14: ...DT List of Figures PES16NT2 User Manual viii April 15 2008 Notes...
Страница 20: ...IDT Register List PES16NT2 User Manual xiv April 15 2008 Notes...
Страница 32: ...IDT PES16NT2 Device Overview PES16NT2 User Manual 1 12 April 15 2008 Notes...
Страница 44: ...IDT Clocking Reset and Initialization Clock Operation PES16NT2 User Manual 2 12 April 15 2008 Notes...
Страница 50: ...IDT Link Operation PES16NT2 User Manual 3 6 April 15 2008 Notes...
Страница 62: ...IDT Power Management PES16NT2 User Manual 5 4 April 15 2008 Notes...
Страница 78: ...IDT SMBus Interfaces PES16NT2 User Manual 6 16 April 15 2008 Notes...
Страница 83: ...IDT NTB Upstream Port Failover PES16NT2 User Manual 7 5 April 15 2008 Notes...
Страница 84: ...IDT NTB Upstream Port Failover PES16NT2 User Manual 7 6 April 15 2008 Notes...
Страница 130: ...IDT Transparent Mode Operation PES16NT2 User Manual 9 44 April 15 2008 Notes...
Страница 284: ...IDT Non Transparent Mode Operation PES16NT2 User Manual 10 154 April 15 2008 Notes...