GS4901B/GS4900B Preliminary Data Sheet
3.10.1 Command Word Description
The command word consists of 16 bits transmitted MSB first and includes a
read/write bit, an Auto-Increment bit and a 12-bit address.
shows the
command word format and bit configurations.
Command words are clocked into the GS4901B/GS4900B on the rising edge of the
serial clock, SCLK, which operates in a burst fashion.
When the Auto-Increment bit is set LOW, each command word must be followed
by only one data word to ensure proper operation. If the Auto-Increment bit is set
HIGH, the following data word will be written into the address specified in the
command word, and subsequent data words will be written into incremental
addresses. This facilitates multiple address writes without sending a command
word for each data word.
Auto-Increment may be used for both read and write access.
MSB
R/W RSV
LSB
RSV
AutoInc
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
RSV = Reserved. Must be set to zero.
R/W: Read command when R/W = 1
Write command when R/W = 0
Figure 3-12: Command Word Format
MSB
D15
LSB
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
Figure 3-13: Data Word Format
3.10.2 Data Read and Write Timing
Read and write mode timing for the GSPI interface is shown in
and
respectively. The timing parameters are defined in
When several devices are connected to the GSPI chain, only one CS should be
asserted during a read sequence.
During the write sequence, all command and following data words input at the
SDIN pin are output at the SDOUT pin as is. Where several devices are connected
to the GSPI chain, data can be written simultaneously to all the devices that have
CS set LOW.
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April 2006
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