SMART Embedded Computing 6806800V18A, Installation And Use Manual

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150 AXP1440-C07 Installation and Use (6806800V18A)
Shelf Management Module
Shelf Management Module
The FPGA device contains a built-in CRC error checker for detecting soft errors in the
configuration data. When a CRC error is detected the signal LATCH_CRC_ERROR is set
active by the ShMM-1500R CRC error detection circuit, which immediately sets the
ShMM_STATUS[0:1]_L and ACTIVE# signals high. The peer ShMM-1500R, if it is not
already active upon detecting the loss of the status serial bit streams, becomes the active
ShMM-1500R.
The HRI also includes 13 test points for in-service monitoring of the hardware redundancy
signals and for out-of-service diagnostics, enabling the ShMM-1500R to isolate failures on
the HRI to a single cShMM-1500R pair.
7.4.2.2 HRI Protocol
In the redundant configuration, the two ShMM-1500R boards communicate through the
HRI by exchanging data packets. The HRI continues to be operational in case of a single
interconnection failure and is able to detect a double failure. The HRI has a redundant
communication path, using four signals. In the case of a single wire permanent failure (the
signal gets stuck high, low or breaks), data packets continue to be transmitted through the
redundant communication path. A short between two of these four signals is considered a
double failure.
7.4.2.3 Ethernet Signals
The ShMM-1500R provides two 100BaseT Ethernet ports, identified within the Linux
environment as eth0 and eth1.The eth0 port is cross-connected to the eth0 port on the
other SAM1620-D to provide a dedicated high-speed inter-SAM link for the exchange of
status and configuration details. The eth1 port is connected to an Ethernet switch (a
Broadcom BCM5325E), which in turn connects to the base ports of the two hub slots and
to the front-panel RJ-45 Ethernet connector.
The port utilization of the switch is:

TP port 1 to Local hub slot

TP port 2 to Remote hub slot
Figure 7-4 SAM1620-D HRI Interconnection
ShMM-1500R A
F_ShMM_STATUS 0
F_ShMM_STATUS 1
ShMM-1500R B
PRES#
GND
GND
ShMM-1500R A buffer ShMM-1500R B buffer