ICS841S01 Datasheet, PDF (3/16 Pages) Integrated Device Technology – PCI EXPRESS™ CLOCK GENERATOR

ICS841S01
PCI EXPRESS™ CLOCK GENERATOR
PRELIMINARY
SERIAL DATA INTERFACE
To enhance the flexibility and function of the clock synthesizer,
a two-signal serial interface is provided. Through the Serial Data
Interface, various device functions, such as individual clock
output buffers, can be individually enabled or disabled. The
registers associated with the Serial Data Interface initialize to
their default setting upon power-up, and therefore, use of this
interface is optional. Clock device register changes are nor-
mally made upon system initialization, if any are required. The
interface cannot be used during system operation for power
management functions.
DATA PROTOCOL
The clock driver serial protocol accepts byte write, byte read,
block write, and block read operations from the controller. For
block write/read operation, the bytes must be accessed in se-
quential order from lowest to highest byte (most significant bit
first) with the ability to stop after any complete byte has been
transferred. For byte write and byte read operations, the sys-
tem controller can access individually indexed bytes. The off-
set of the indexed byte is encoded in the command code, as
described in Table 3A.
The block write and block read protocol is outlined in Table 3B,
while Table 3C outlines the corresponding byte write and byte
read protocol. The slave receiver address is 11010010 (D2h).
TABLE 3A. COMMAND CODE DEFINITION
BIT Description
7 0 = Block read or block write operation, 1 = Byte read or byte write operation.
6:5 Chip select address, set to "00" to access device.
4:0
Byte offset for byte read or byte write operation. For block read or block write operations, these bits must be
"00000".
TABLE 3B. BLOCK READ AND BLOCK WRITE PROTOCOL
BIT
1
2:8
9
10
11:18
19
20:27
28
29:36
37
38:45
46
Description = Block Write
Start
Slave address - 7 bits
Write
Acknowledge from slave
Command Code - 8 bits
Acknowledge from slave
Byte Count - 8 bits
Acknowledge from slave
Data byte 1 - 8 bits
Acknowledge from slave
Data byte 2 - 8 bits
Acknowledge from slave
Data Byte/Slave Acknowledges
Data Byte N - 8 bits
Acknowledge from slave
Stop
BIT
1
2:8
9
10
11:18
19
20
21:27
28
29
30:37
38
39:46
47
48:55
56
Description = Block Read
Start
Slave address - 7 bits
Write
Acknowledge from slave
Command Code - 8 bits
Acknowledge from slave
Repeat start
Slave address - 7 bits
Read = 1
Acknowledge from slave
Byte Count from slave - 8 bits
Acknowledge
Data Byte 1 from slave - 8 bits
Acknowledge
Data Byte 2 from slave - 8 bits
Acknowledge
Data Bytes from Slave / Acknowledges
Data Byte N from slave - 8 bits
Not Acknowledge
IDT^™ / ICS^™ PCI EXPRESS CLOCK GENERATOR
3
ICS841S01BG REV. B MAY 23, 2007