PolarFire FPGA 1G Ethernet Loopback Using IOD CDR
Microsemi Proprietary DG0799 Demo Guide Revision 3.0
4
Figure 1 •
Block Diagram
2.3.1
About PF_IOD_CDR
The PF_IOD_CDR IP core provides an asynchronous receive and transmit interface that supports upto
1.6 Gbps speed for serial data transfers. It supports the SGMII interface. PF_IOD_CDR uses the DDRX5
IO gearing mode for the SGMII interface with a 10:1 digital ratio to provide the 10-bit data width for both
transmit and receive. The clock recovery circuit, which is part of this PF_IOD_CDR, keeps the receive
clock centered in the data eye.
The PF_IOD_CDR interface is compatible with the CoreTSE, CoreTSE_AHB, and CoreSGMII IP cores
configured in TBI mode. In this demo, the CoreTSE (Non-AMBA) MAC is used in the TBI mode to
transmit and receive the Ethernet packets.
2.3.1.1
Receive interface
The PF_IOD_CDR IP includes the clock recovery block, which is used to generate the recovered clock
for sampling the incoming data stream. This IP uses the four clocks of phases 0, 90,180 and 270
degrees for the clock recovery. The recovered clock (RX_CLK_R) is used by the fabric for sampling the
Rx data from the PF_IOD_CDR IP. The CoreTSE logic also uses this clock.
For more information PF_IOD_CDR and its blocks, see
UG0686: PolarFire FPGA User I/O User Guide
2.3.1.2
Transmit Interface
The PF_IOD_CDR transmit interface receives the parallel data (TX_DATA[9:0]), converts it into a serial
data stream using the IOD interface, and then transmits it via the I/O ports TX_P and TX_N. The 625
MHz clock generated by the PF_IOD_CDR_CCC is used by PF_IOD_CDR transmit interface to transmit
the data serially on the TX_P/TX_N ports.
For more information about PF_IOD_CDR, see
UG0686: PolarFire FPGA User I/O User Guide.
PF_IOD_CDR
at
1250 Mbps
PolarFire Evaluation Board
RX_P
TX_P
RJ45
Host PC
Ethernet Test
Solution
(cat KARAT,
Wireshark)
CoreTSE
VSC8575
Ethernet
Copper
PHY
RCG
TCG
RX_DATA
TX_DATA
RX_N
TX_N
APB_S
PolarFire FPGA
Mi-V
SoftProcessor
AHB_MST_MMIO
AHB lite
AHB_APB
Bridge
CoreSPI
ZL 30364
REF_CLK
APB slave
APB slave
AHB slave
pf_sram
PF_IOD_CDR_CCC
RX DATA
TX DATA
AHB_MST_MEM
Packets
transmitted from
host PC catKARAT
to fabric
Packets received
at host PC from
fabric
SGMII
SGMII
TBI
MDIO Interface
HS_IO_CLK
TBI_TX_CLK
TX_CLK_G
