2.3.7.1
Hot-Swap Process
The AM4520 AMC has the ability to be hot-swapped in and out of a AMC Carrier. The onboard MMC
manages the AMC’s power-up and power-down transitions. The list below illustrates this process for
power down request.
1-
Ejector latch is opened. HOT_SWAP_PB# assertion. MMC firmware detects the assertion of
this signal.
2-
MMC sends "Module Handle Open" event message to AMC Carrier. The corresponding M
state of AMC Carrier moves from M4-> M5.
3-
AMC Carrier moves from M5 -> M6 if the SHMC grants the request and then send the FRU
Control requesting quiesced state to the AMC.
4-
The firmware deasserts payload power and sends "Module Quiesced" event message to the
AMC Carrier where it transitions from M6 to M1 state.
2.3.7.2
Hot-Swap LED
The AM4520 supports a blue Hot Swap LED mounted on the front panel. This LED indicates when it is
safe to remove the AMC from the AMC Carrier. The on-board MMC drives this LED to indicate the hot-
swap state. The following states are possible:
LED state
Description
OFF
AMC is in M4 state, normal state when board is in operation.
ON
Ready for hot swap.
Short blink
M5 state deactivation request
Long blink
M2 state Activation Request.
When the AMC latch is disengaged from the faceplate, the hot swap switch embedded in the PCB will
assert a "HOT_SWAP_PB#" signal to the MMC, and the MMC will send Module Handle Open" event
message to the AMC Carrier wich move from the M4 state to the M5 state. At the M5 state, the AMC
Carrier will ask the SHMC (or Shelf Manager) for permission to move the AMC to the M6 state. Then
the Carrier AMC will set the AMC Hot Swap LED to indicate this state with a short blink. Once
permission is received from the SHMC or higher-level software, the AMC carrier will move to the M6
state.
The SHMC or higher level software can reject the request to move to the M6 state. If this occurs, the
AMC Carrier will returns the Hot Swap LED to a solid off condition, indicating that the AMC has
returned to M4 state.
If the AMC Carrier reaches the M6 state, either through an extraction request through the AMC
handle latch, the MMC communicates to the AMC Carrier that the module must discontinue
operation in preparation for removal. The Hot Swap LED continues to flash during this preparation
time, just like it does at the M5 state. When main AMC payload power is successfully removed from
the AMC Bay, the Hot Swap LED remains lit, indicating it is safe to remove the AMC from the AMC
Carrier.
LED Status
Meaning
Off Normal
status
Blinking Blue
Preparing for removal/insertion: Long blink indicates activation is in progress,
short blink when deactivation is in progress.
Solid Blue
Ready for hot swap
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AM4520 User’s Guide
