
5–52 Chapter 5: IP Core Interfaces
Avalon-MM Application Interface
IP Compiler for PCI Express User Guide August 2014 Altera Corporation
Figure 5–40 shows the IP Compiler for PCI Express reset logic in Qsys systems.
Pcie_rstn
also resets the rest of the IP Compiler for PCI Express, but only after the
following synchronization process:
1. When
pcie_rstn
asserts, the reset request module asserts
reset_request
,
synchronized to the Avalon-MM clock, to the Reset Synchronizer block.
2. The Reset Synchronizer block sends a reset pulse,
reset_n_pcie
, synchronized to
the Avalon-MM clock, to the IP Compiler for PCI Express.
3. The Reset Synchronizer resynchronizes
reset_n_pcie
to the IP Compiler for PCI
Express clock (
pcie_core_clk
or
clk125_out
) to reset the PCI Express Avalon-MM
bridge as well as the three IP Compiler for PCI Express layers with
srst
and
crst
.
4. The
reset_request
signal deasserts after
Reset_n_pcie
asserts.
The system-wide reset,
reset_n
, resets all IP Compiler for PCI Express circuitry not
affected by
Pcie_rstn
. However, the reset logic first intercepts the asynchronous
reset_n
, synchronizes it to the Avalon-MM clock, and sends a reset pulse,
Reset_n_pcie
, to the IP Compiler for PCI Express. The Reset Synchronizer
resynchronizes
Reset_n_pcie
to the IP Compiler for PCI Express clock to reset the PCI
Express Avalon-MM bridge as well as the three IP Compiler for PCI Express layers
with
srst
and
crst
.
Figure 5–40. PCI Express Reset Diagram
Note to figure
(1) The system-wide reset,
reset_n/avalon_reset
, indirectly resets all IP Compiler for PCI Express circuitry not affected by
PCIe_rstn/pcie_rstn_export
using the
reset_n_pcie
signal and the Reset Synchronizer module.
(2) For a description of the
ltssm[4:0]
bus, refer to Table 5–7.
System Interconnect Fabric
Reset_n PCIe_rstn
npor
npor
srst
crst
l2_exit
hotrst_exit
dlup_exit
dl_ltssm[4:0]
Reset_request
RxmResetRequest_o
Reset Request
Module
PCI Express
Avalon-MM Bridge
Transaction Layer
Data Link Layer
Physical Layer
IP Compiler for PCI Express
Rstn_i
Reset_n_pcie
Reset Synchronizer
(to Avalon-MM clock)
Reset Synchronizer
(to IP Compiler for PCI Express
Clock)
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