BECKHOFF ET1100 - Manual (Page 82)

PDI description
III-68 Slave Controller – ET1100 Hardware Description
6.4.6 µController access errors
These reasons for µController access errors are detected by the µController interface:

Read or Write access to the 16 bit interface with A[0]=1 and BHE(act. low)=1, i.e. an access to an
odd address without Byte High Enable.

Deassertion of WR (or deassertion of CS while WR remains asserted) while the µController
interface is BUSY.

Deassertion of RD (or deassertion of CS while RD remains asserted) while the µController
interface is BUSY (read has not finished).
A wrong µController access will have these consequences:

The PDI error counter 0x030D will be incremented.

For A[0]=1 and BHE(act. low)=1 accesses, no access will be performed internally.

Deassertion of WR (or CS) while the µController interface is BUSY might corrupt the current and
the preceding transfer (if it is not completed internally). Registers might accept write data and
special functions (e.g., SyncManager buffer switching) might be performed.

If RD (or CS) is de-asserted while the µController interface is BUSY (read has not finished), the
access will be terminated internally. Although, internal byte transfers might be completed, so
special functions (e.g., SyncManager buffer switching) might be performed.
6.4.7 EEPROM_LOADED
The EEPROM_LOADED signal indicates that the µController Interface is operational. Attach a pull-
down resistor for proper function, since the PDI pin will not be driven until the EEPROM is loaded.
6.4.8 Connection with 16 bit µControllers without byte addressing
If the ESC is connected to 16 bit µControllers/DSPs which only support 16 bit (word) addressing,
ADR[0] and BHE of the EtherCAT device have to be tied to GND, so the ESC will always perform 16
bit accesses. All other signals are connected as usual. Please note that ESC addresses have to be
divided by 2 in this case.
CS CS
ADR[14:0]
RD
BUSY
DATA[15:0]
WR
ADR[15:1]
ADR[0]
RD
BUSY
DATA[15:0]
WR
16 bit µController, async,
only 16 bit addressing
EtherCAT device
IRQ IRQ
BHE
General purpose input EEPROM_Loaded
optional
Figure 23: Connection with 16 bit µControllers without byte addressing