BECKHOFF EtherCAT IP Core for Altera FPGAs v3.0.10 - Manual (Page 120)

PDI Description
III-108 Slave Controller – IP Core for Altera FPGAs
10.3.8 Connection with 8 bit µControllers
If the ESC is connected to 8 bit µControllers, the BHE signal as well as the DATA[15:8] signals are not
used.
CS CS
ADR[15:0]
RD
BUSY
WR
ADR[15:0]
RD
BUSY
DATA[15:8] (unused)
WR
8 bit µController, async
EtherCAT device
IRQ IRQ
BHE (unused)
General purpose input EEPROM_Loaded
optional
DATA[7:0] DATA[7:0]
Figure 48: Connection with 8 bit µControllers (BHE and DATA[15:8] should not be left open)