GS2985 Datasheet, PDF (29/45 Pages) Gennum Corporation – Uses standard 27MHz crystal

4.15.6 Write Operation - Single Device
A Write operation consists of a 16 bit command word and a 16 bit data word, followed
by 32 cycles with the slave SDI held HIGH. When writing to a single non-daisy chained
device, the following format should be used:
16 bit command
rw 0 0 R _A[4:0]
C[6:0] = 0
R/W Reset Address
Chain Position
CS
MOSI ^{CCoommmmaanndd [15:0]}
Data [1155::0]]
Data High 32 cycles
MISO
Command’ [15:0]
Data [15:0]
Figure 4-6: Single Device Write
1. At power-up, the device should be reset by setting the Reset bit low. A simple way
to accomplish a reset is to hold the slave SDI line low for an entire 64 cycle
communication.
2. For a Write operation, the R/W bit should be set to 0.
3. The 2nd and 3rd bits are Reserved and should be set to 0.
4. The Reset bit should always be set HIGH for a normal Write operation.
5. Refer to the Register Map for information on Address and Data bits.
6. The slave SDI line shall be held high for 32 cycles before de-asserting Chip Select
Bar.
4.15.7 Read Operation - Single Device
For Reading from a device the following format should be used:
16 bit command
rw 0 0 R _A[4:0]
C[6:0] = 0
R/W Reset Address
Chain Position
CS
MOSI Command [15:0]
Data High 16 cycles
Data High 16 cycles
Data High 16 cycles
MISO
Command’ [15:0]
Data [15:0]
Figure 4-7: Single Device Read
GS2985 Multi-Rate SDI Reclocker with Equalization &
De-emphasis
Data Sheet
36663 - 5
July 2012
29 of 45
Proprietary & Confidential