AR #33720 - Virtex-5 FPGA Embedded Tri-mode Ethernet MAC Wrapper v1.6 - Setting Offset constraints for GMII and RGMII

AR#	33720
Part	IP-DS-Embedded Tri-Mode EMAC
Last Modified	2009-10-28 00:00:00.0
Status	Active
Keywords	Virtex-5, TEMAC, tri-speed, patch, installation, instruction, ip0_L, IP Update 1, LXT, SXT, FXT

Solution

The following offset constraints can be added to the example design UCF file. The '#' corresponds to EMAC0 or EMAC1.

1) For a GMII interface (non Byte-PHY):
# Identify GMII Rx Pads
INST "gmii_rxd_#<?>" TNM = "gmii_rx_#";
INST "gmii_rx_dv_#" TNM = "gmii_rx_#";
INST "gmii_rx_er_#" TNM = "gmii_rx_#";

# Constrain GMII inputs for 2 ns setup time and 0 ns hold time, with respect
# to rising edge of GMII_RX_CLK_#
TIMEGRP "gmii_rx_#" OFFSET = IN 2 ns VALID 2 ns BEFORE "GMII_RX_CLK_#" RISING;

2) For a Byte-PHY GMII interface:

# Identify GMII Rx Pads
INST "gmii_rxd_#<?>" TNM = "gmii_rx_#";
INST "gmii_rx_dv_#" TNM = "gmii_rx_#";
INST "gmii_rx_er_#" TNM = "gmii_rx_#";

# Constrain GMII inputs for 2 ns setup time and 0 ns hold time, with respect
# to both the rising and falling edges of GMII_RX_CLK_0
TIMEGRP "gmii_rx_#" OFFSET = IN 2 ns VALID 2 ns BEFORE "GMII_RX_CLK_#" RISING;
TIMEGRP "gmii_rx_#" OFFSET = IN 2 ns VALID 2 ns BEFORE "GMII_RX_CLK_#" FALLING;


3) For an RGMII interface:
# Identify RGMII Rx Pads
INST "rgmii_rxd_#<?>" TNM = "rgmii_rx_#";
INST "rgmii_rx_ctl_#" TNM = "rgmii_rx_#";

# Constrain RGMII inputs for 1 ns setup time and 1 ns hold time, with respect
# to both the rising and falling edges of RGMII_RXC_#
TIMEGRP "rgmii_rx_#" OFFSET = IN 1 ns VALID 2 ns BEFORE "rgmii_rxc_#" RISING;
TIMEGRP "rgmii_rx_#" OFFSET = IN 1 ns VALID 2 ns BEFORE "rgmii_rxc_#" FALLING;

The offset constraints may need to be adjusted for particular board and PHY interfaces depending on the clock and data skew coming into the FPGA for a particular system. The IDELAY_VALUEs specified in the UCF file may need to be adjusted for a particular device and pinout. More details on I/O timing and setting IDELAY constraints can be found in the Virtex-5 Embedded Tri-Mode Ethernet MAC Wrapper Getting Started Guide in the Constraining the Example Design Appendix:
http://www.xilinx.com/support/documentation/ip_documentation/v5_emac_gsg340.pdf