I2C Reset; Board Management Microcontroller - GE SBC330 3U VPX Hardware Reference Manual

40 SBC330 3U VPX Single Board Computer
2
5.7.7 I C reset
There is the potential for the I
during the tenure of a slave device (without a reset pin) driving out data when the
2
I C clock is stopped. The Local Bus Control FPGA provides logic to recover both
2
I 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
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').
Table 5-12 BMM Address Allocation
2
I C
Slot GA[4:0]
Address
1 11110 0xB0
2 11101 0xB2
3 11100 0xB4
4 11011 0xB6
5 11010 0xB8
6 11001 0xBA
7 11000 0xBC
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.
2
C bus to become locked‐up if a RESET is applied
2
C Serial Management bus (using the SM0
2
I C
Slot GA[4:0]
Address
8 10111 0xBE
9 10110 0xC0
10 10101 0xC4
11 10100 0xC6
12 10011 0xC8
13 10010 0xCA
14 10001 0xCC
2
I C
Slot GA[4:0]
Address
15 10000 0xCE
16 01111 0xD0
17 01110 0xD2
18 01101 0xD4
19 01100 0xD6
20 01011 0xD8
21 01010 0xDA
Publication No. SBC330-0HH/3