PT AMC123, Руководство пользователя

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Chapter 6: Reset
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Hard Reset
Hard resets may originate from the following sources:
• Intel EP80579 Integrated Processor initiated system reset request
• Payload reset initiated by the MMC
• Payload reset initiated by the carrier
• Front panel reset button
• Intel EP80579 Integrated Processor watchdog timer
• Setting of custom bits
• Loss of signal from AMC 100 MHz clock
Intel EP80579 Integrated Processor Initiated System Reset Request
The Intel EP80579 Integrated Processor chipset asserts PLTRST_N during power-up and
when a hard reset sequence is initiated through the CF9h register.
Payload Reset Initiated by the MMC
The MMC can drive a payload reset that results in a hard reset. The MMC circuitry has an
independent power-on reset circuit that is controlled by MMC power. A brown-out reset occurs
for the MMC when the MMC power drops below 2.7 V. The MMC monitors the payload reset,
but does not allow this reset to directly reset the MMC circuitry.
A watchdog timer within the MMC can reset the MMC. The MMC ICE interface can also reset
the MMC.
Payload Reset Initiated by the Carrier
The carrier can reset the MMC directly through the ENABLE_N signal.
When the AMC123 is extracted from a carrier, the carrier hot-swap controller unconditionally
removes backend power from the AMC123 and holds it in reset. The backend logic is powered
off. All on-board devices are reset.
Front Panel Reset Button
When the system reset button (see
Figure 2-1, “AMC123 Front Panel,” on page 23
) on the front
panel is pressed, the AMC123 resets itself.
Intel EP80579 Integrated Processor Watchdog Timer
The watchdog timer can be used to cause an interrupt that allows the processor to attempt
deadlock recovery. It can then be reprogrammed to automatically cause a reset upon failure to
service the interrupt.