n82802 Intel Corporation, n82802 Datasheet - Page 42

• Manufacturer Part Number: n82802
• Description: Firmware Hub Fwh
• Manufacturer: Intel Corporation

Intel
5.4.1.2.
5.4.1.3.
42
Figure 10.
Table 17.
®
82802AB/AC Firmware Hub
Single-Byte Read Waveforms
Write Cycle Sequence
The firmware hub only supports single-byte writes. Each byte represents either the data to be written or a
valid flash command. Refer to the waveforms in Figure 11.
FWH[3:0]
Clock
Cycle
3-9
FWH Single-Byte Read Waveforms
FWH Write Cycle
FWH4
10
11
12
13
14
15
CLK
1
2
IMADDR
RSYNC
START
IMSIZE
IDSEL
Name
DATA
DATA
TAR0
TAR1
Field
STR
IDS
Field Contents
0000 (1 byte)
1111 (float)
FWH[3:0]
YYYY
YYYY
YYYY
1110
0000
1111
1111
0000
to
IMADDR
1
FWH[3:0]
Float then
Direction
then float
OUT
OUT
IN
IN
IN
IN
IN
IN
IN
IMS
TAR
FWH4 must be active (low) for the part to respond.
Only the last start field (before FWH4 transitioning
high) should be recognized. The START field
contents indicate an FWH memory write cycle.
Indicates which FWH device should respond. If the
IDSEL (ID select) field matches the value ID[3:0],
then that particular device will respond to subsequent
commands.
These seven clock cycles make up the 28-bit
memory address. YYYY is one nibble of the entire
address. Addresses are transferred most-significant
nibble first.
This size field indicates how many bytes will be
transferred during read/write operations. The FWH
only supports single-byte writes.
This field is the least-significant nibble of the data
byte. This data is either the data to be programmed
into the flash memory or any valid flash command.
This field is the most-significant nibble of the data
byte.
In this clock cycle, the master (Intel ICH) has driven
the bus to all 1s and then floats the bus prior to the
next clock cycle. This is the first part of the bus
“turnaround cycle.”
The FWH takes control of the bus during this cycle.
During the next clock cycle it will be driving the “sync”
data.
The FWH outputs the values 0000, indicating that it
has received data or a flash command.
SYNC(3)
DATA
Comments
TAR
Datasheet
R