BECKHOFF ET1100 - Manual (Page 70)

PDI description
III-56 Slave Controller – ET1100 Hardware Description
6.3.4 Commands
The command CMD0 in the second address/command byte may be READ, READ with following Wait
State bytes, WRITE, NOP, or Address Extension. The command CMD1 in the third address/command
byte may have the same values:
Table 58: SPI commands CMD0 and CMD1
CMD[2] CMD[1] CMD[0] Command
0 0 0 NOP (no operation)
0 0 1 reserved
0 1 0 Read
0 1 1 Read with following Wait State bytes
1 0 0 Write
1 0 1 reserved
1 1 0 Address Extension (3 address/command bytes)
1 1 1 reserved
6.3.5 Address modes
The SPI slave interface supports two address modes, 2 byte addressing and 3 byte addressing. With
two byte addressing, the lower 13 address bits A[12:0] are selected by the SPI master, while the upper
3 bits A[15:13] are assumed to be 000b inside the SPI slave, thus only the first 8 Kbyte in the
EtherCAT slave address space can be accessed. Three byte addressing is used for accessing the
whole 64 Kbyte address space of an EtherCAT slave.
For SPI masters which do only support consecutive transfers of more than one byte, additional
Address Extension commands can be inserted.
Table 59: Address modes without (Read access without Wait state byte)
Byte 2 Byte address mode 3 Byte address mode
0 A[12:5] address bits [12:5] A[12:5] address bits [12:5]
1 A[4:0] address bits [4:0]
CMD0[2:0] read/write command
A[4:0] address bits [4:0]
CMD0[2:0] 3 byte addressing: 110b
2 D0[7:0] data byte 0 A[15:13] address bits [15:13]
CMD1[2:0] read/write command
res[1:0]
two reserved bits, set to 00b
3 D1[7:0] data byte 1 D0[7:0] data byte 0
4 ff. D2[7:0] data byte 2 D1[7:0] data byte 1