User Manual
BCM1250/BCM1125/BCM1125H
10/21/02
B r o a d c o m C o r p o r a t i o n
Document
1250_1125-UM100CB-R
Section 14: Serial Configuration Interface Page
417
Table 295: SMBus Packet Error Check Registers
smb_pec_0 -
00_1006_0070
smb_pec_1 -
00_1006_0078
Read returns value from previous smbus read command. Write sets value for next smbus write command.
Bits
Name
Default
Description
7:0
pec
8’h0
This register holds the PEC information that is sent or received for a command that
has the smb_pec bit set. The hardware does not generate or check the CRC,
software must do that.
63:8
notimp
56’bx
Not implemented.
Table 296: SMBus Start and Command Registers SMBus Mode
smb_start_0 -
00_1006_0040
smb_start_1 -
00_1006_0048
Bits
Name
Default
Description
6:0
smb_addr
7'h0
The serial interface address. These 7 bits are used to form the address byte that
is sent across the serial interface.
7
smb_qdata
1'b0
Bit of data to send as R/W bit in a Quick Command. Ignored, write as zero for all
other commands.
10:8
smb_tt
3'h0
Value Transfer Type
000
1 byte write (address, command).
001
2 byte write (address, command, write least significant field of smb_data).
010
3 byte write (address, command, write both fields of smb_data).
011
Command and 1 byte read (address, command, address, read byte into LB
field of smb_data).
100
Command and 2 byte read (address, command, address, read byte into LB
field of smb_data, read byte into HB field of smb_data).
101
1 byte read (address, read byte into LB field of smb_data).
110
Quick Command (address with one bit of data).
111
EEPROM Read. Reads 32 bits into
smb_data
and
smb_xtra
from a
standard EEPROM >16 kbit that needs 2 address bytes.
13:11
reserved
3'h0
reserved, set to zero
14
extend
1'b0
This bit should be set to zero for SMBus protocol mode.
15
smb_pec
1'b0
Set to modify the transfer type to use Packet Error Checking as defined in the
SMBus 1.1 specification. Zero for regular operation.
63:16
notimp
48'bx
Not Implemented.