BECKHOFF EtherCAT IP Core for Xilinx FPGAs v2.04e - Manual (Page 123)

Synthesis Constraints
Slave Controller – IP Core for Xilinx FPGAs III-111
14 Synthesis Constraints
The following table contains basic IP Core constraints.
Table 65: EtherCAT IP Core constraints
Signal Requirement Value Clock reference Description
CLK25 period 40 ns Reference clock (25 MHz)
CLK50
a) period
b) phase shift a) 20 ns
b) 0 ns
CLK25
Derived clock (50 MHz). Phase shift is rising
edge to rising edge.
CLK100
a) period
b) phase shift a) 10 ns
b) 0 ns
CLK25
Derived clock (100 MHz). Phase shift is
rising edge to rising edge.
nRESET Ignore timing nRESET is asynchronous to any clock
MCLK min. period 400 ns IEEE802.3 requirement (2.5 MHz)
MDIO
a) setup
b) hold
at PHY input
a) 10 ns
b) 10 ns MCLK
(rising edge)
MDIO is changed with falling edge of
MCLK, max. output skew of MCLK and
MDIO is 190 ns. Constraining is usually not
required. IEEE802.3 requirement.
MII_RX_CLK0-2 period 40 ns
MII receive reference clock (25 MHz).
IEEE802.3 requirement.
MII_RX_DATA0-2[3:0]
MII_RX_DV0-2
MII_RX_ERR0-2
a) setup
b) hold a) 10 ns
b) 10 ns MII_RX_CLK0-2
(rising edge)
IEEE802.3 requirement
MII_TX_CLK0-2 period 40 ns
MII transmit reference clock (25 MHz). Only
used for automatic TX Shift compensation.
IEEE802.3 requirement.
MII_TX_DATA0-2[3:0]
MII_TX_ENA0-2
Clock-to-Pin
a) min
b) max
a) 0 ns
b) 25 ns TX_CLK0-2 from
PHY (rising
edge)
IEEE802.3 requirement
Clock-to-Pin
a) min
b) max
a) 0 ns
b) 10 ns
CLK25
(rising edge)
Incomplete alternative to IEEE802.3
requirement, keeps margin if TX Shift has
been determined and compensated. Refer
to section III for details.
PROM_CLK period App. dep.
I²C clock. Actual ESC output clock is
6.72 µs (
≈ 150 kHz). Min. 2.5µs (400 Khz)
for example I²C EEPROM chip.
PROM_DATA
a) setup
b) hold
a) 250 ns
b) 0 ns PROM_CLK
a) rising edge
b) falling edge
PROM_DATA is changed in the middle of
the low phase of PROM_CLOCK, i.e., max.
output skew of PROM_CLK/PROM_DATA
is 1.43 µs. Constraining is usually not
required. Example I²C EEPROM chip
requirement.
RMII_RX_DATA0/1[1:0]
RMII_RX_DV0/1
RMII_RX_ERR0/1
RMII_TX_DATA0/1[1:0]
RMII_TX_ENA0/1
a) setup
b) hold a) 4 ns
b) 2 ns CLK50
(rising edge)
RMII specification requirement
Other signals, especially
PDI signals
application dependent