W5500 Datasheet, PDF (17/65 Pages) List of Unclassifed Manufacturers – Supports 8 independent sockets simultaneously

- Fixed Length Data Mode (FDM)
: In FDM, the Data Length is set by OM[1:0], these are not „00‟
value. So, the SCSn signal should be Low state, and has one
Length type (among 1 Bytes, 2 Bytes, 4 Bytes) according to the
OM[1:0] value. (Refer to the Figure 5.)
The next table shows the SPI Operation Mode according to the
OM[1:0].
OM[1:0]
00
01
10
11
Meaning
Variable Data Length Mode, N-Bytes Data Phase (1 ≤ N)
Fixed Data Length Mode , 1 Byte Data Length (N = 1)
Fixed Data Length Mode , 2 Byte Data Length (N = 2)
Fixed Data Length Mode , 4 Byte Data Length (N = 4)
2.2.3
Data Phase
With the Control Phase set by the SPI Operation Mode Bits OM[1:0], the Data Phase
is set by two types of length, one type is the N-Bytes length (VDM mode) and the
other type is 1/2/4 Bytes (FDM mode).
At this time, 1 byte data is transferred through MOSI or MISO signal from MSB to
LSB sequentially.
2.3
Variable Length Data Mode (VDM)
In VDM mode, the SPI Frame Data Phase Length is determined by SCSn Control of
the External Host. That means that the Data Phase Length can have random value
(Any length from 1 Byte to N Bytes) according to the SCSn Control.
The OM[1:0] of the Control Phase should be „00‟ value in VDM mode.
W5500 Datasheet Version1.0 (August 2013)
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