BECKHOFF PHY - Manual (Page 6)

PHY Connection
Slave Controller – Application Note PHY Selection Guide 3
3 PHY Connection
Figure 2 shows the principle connection between ESC 5 and PHY. The clock source of Ethernet PHYs and ESC
has to be the same quartz or quartz oscillator. TX_CLK is usually not connected unless automatic TX Shift
compensation is used, because the ESCs do not incorporate a TX FIFO. The TX signals can be delayed inside
the ESC for TX_CLK phase shift compensation. LINK_STATUS is an LED output indicating a 100 Mbit/s (Full
Duplex) link.
Refer to ESC data sheet Section III for details about Ethernet PHY connection of a specific ESC.
Ethernet PHY
2
5
M
H
z
OSC_OUT
OSC_IN CLK25OUT
RX_DV
RXD[3:0]
RX_ER
TX_EN*
TXD[3:0]*
RX_CLK
RX_DV
RXD[3:0]
RX_ER
TX_EN
TXD[3:0]
RX_CLK
TX_CLK
CLK25
CRS
TX_ER
COL
LINK_MII LINK_STATUS
25 MHz Option: one quartz oscillator for
ESC and PHYs
MDIO
MDC*
MDIO
MDC
4
K
7
V CC I/O
* Configuration input (ESC dependent)
TX signal delay
configuration
0 ns
10 ns
20 ns
30 ns
TX_CLK
IP Core opt. with
Auto-TX-Shift:
ESC
Figure 2: PHY Connection
5 ESC10/20 uses TX_CLK of a PHY as the clock source of the ESC. FPGAs with IP Core only support the quartz oscillator
alternative.
3.1 Required Ethernet PHY signals
Table 1: Required Ethernet PHY signals using MII
Signal Required Comment
CLK25 Mandatory Shared 25 MHzclock source between ESC and PHY
LINK_STATUS Mandatory LINK LED signal, required for fast link loss reaction time
RX_CLK Mandatory
RX_DV Mandatory
RXD[3:0] Mandatory
RX_ER Mandatory Required for error detection and error source localization
COL Not used EtherCAT uses full duplex only
CRS Not used EtherCAT uses full duplex only
TX_CLK Optional Optional for automatic TX Shift compensation
TXD[3:0] Mandatory
TX_ER Not used Connect to GND
MDIO Optional Recommended especially for debugging
MDC Optional Recommended especially for debugging
Table 2: Required Ethernet PHY signals using RMII
Signal Required Comment
REF_CLK Mandatory Shared 50 MHz clock source between ESC and PHY
LINK_STATUS Mandatory LINK LED signal, required for fast link loss reaction time
CRS_DV Mandatory
RXD[1:0] Mandatory
RX_ER Mandatory Required for error detection and error source localization
TX_EN Mandatory
TXD[1:0] Mandatory
MDIO Optional Recommended especially for debugging
MDC Optional Recommended especially for debugging