Beckhoff EtherCAT IP Core for Xilinx FPGAs v2.04e Manuale Utente Scaricare il pdf (Pagina 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

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