40 SBC330 3U VPX Single Board Computer
Publication No. SBC330-0HH/3
5.7.7 I
2
C reset
There
is
the
potential
for
the
I
2
C
bus
to
become
locked
‐
up
if
a
RESET
is
applied
during
the
tenure
of
a
slave
device
(without
a
reset
pin)
driving
out
data
when
the
I
2
C
clock
is
stopped.
The
Local
Bus
Control
FPGA
provides
logic
to
recover
both
I
2
C
buses
from
this
locked
‐
up
state
by
clocking
the
bus
during
reset
until
the
data
line
is
released.
5.7.8 Board Management Microcontroller
The
SBC330
contains
a
Board
Management
Microcontroller
(BMM),
which
provides
a
proprietary
mechanism
to
share
BIT
results
between
boards
in
a
system
and
remote
monitoring
of
board
status.
The
BMM
is
connected
to
a
backplane
I
2
C
Serial
Management
bus
(using
the
SM0
and
SM1
connections
on
the
VPX
P0
connector),
which
is
bused
between
all
slots
in
the
system.
The
BMM
on
each
board
is
addressed
according
to
its
Geographic
Address
as
shown
in
Table
5
‐
12.
These
are
the
Byte
addresses
that
would
be
used
to
write
to
the
device
on
the
bus
(i.e.
the
7
‐
bit
device
address
and
the
least
significant
bit
set
to
‘0’).
The
local
processor
communicates
with
the
BMM
via
the
COM2
port
from
the
MPC8641D.
The
BMM
serial
interface
is
enabled
when
the
BMM
Communications
Mode
bit
in
the
BMM
Control
register
is
set
to
1.
The
BMM
is
programmed
from
the
BMM
Control
register.
Programming
may
only
be
performed
when
NVMRO
signal
from
the
VPX
backplane
is
negated
(current
firmware
has
not
implemented
this
register
function)
The
BMM
is
powered
from
the
P3V3_AUX
rail,
meaning
that
board
configuration
information
or
BIT
status
can
be
read
out
of
the
device
without
enabling
the
main
on
‐
board
power.
Table 5-12 BMM Address Allocation
Slot GA[4:0]
I
2
C
Address
Slot GA[4:0]
I
2
C
Address
Slot GA[4:0]
I
2
C
Address
1
11110
0xB0
8
10111
0xBE
15
10000
0xCE
2
11101
0xB2
9
10110
0xC0
16
01111
0xD0
3
11100
0xB4
10
10101
0xC4
17
01110
0xD2
4
11011
0xB6
11
10100
0xC6
18
01101
0xD4
5
11010
0xB8
12
10011
0xC8
19
01100
0xD6
6
11001
0xBA
13
10010
0xCA
20
01011
0xD8
7
11000
0xBC
14
10001
0xCC
21
01010
0xDA