BECKHOFF EtherCAT Technology Section I - Manual (Page 100)

SII EEPROM
I-80 Slave Controller – Technology
11.3.3.2 Read Access
An EEPROM read access reads 2 or 4 words (4 or 8 bytes, depending on device capabilities) from the
EEPROM, the load or reload EEPROM access typically reads 8 words (16 bytes). The address wrap-
around at the end of the EEPROM address space has to be taken into account by the application; the
ESC has no knowledge about it.
The ESC will perform the following steps for a read access to the EERPOM. At first, the address is
written to the EEPROM, then the data is read (N=3 or N=7):
Table 45: I²C Read Access
Step Description Up to 16 Kbit 32 Kbit – 4 Mbit
1 Start condition
2 Control Byte (Write) A[10:8] A[18:16]
3* High Address Byte Not present A[15:8]
4 Low Address Byte A[7:0] A[7:0]
5 Start condition
6 Control Byte (Read) A[10:8] A[18:16]
7 Data Byte 0 D0 [7:0]
8 Data Byte 1 D1 [7:0]
… … …
N+7 Data Byte N DN [7:0]
N+8 Stop condition
* This step is only for EEPROMs larger than 16 Kbit.
11.3.4 Timing specifications
Table 46: EEPROM timing characteristics
Parameter Comment
t
Clk
EEPROM clock period
t
Write
Write access time (without errors)
t
Read
Read access time (without errors)
t
Delay
Time until configuration loading begins after
Reset is gone
R/W 1 0 0 1
EEPROM_CLK
A10 EEPROM_DATA
t
Clk
A8 A9 Ack A7 A5 A6 A4 A2 A3 A1 Ack
Start Control Byte Low Address Byte
D3 D1 D2 Ack D15 D13 D14 D12 D10 D11 D9 D8
Data Byte 0 Data Byte 1
D0 D7 D5 D6 D4
EEPROM_CLK
EEPROM_DATA
Stop
Ack
A0
t
Write
t Write
Figure 38: Write access (1 address byte, up to 16 Kbit EEPROMs)