PM3351-SW datasheet(73/268 Pages) PMC

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PM3351 ELAN 1X100

DATA SHEET

PMC-970113

ISSUE 3

SINGLE PORT FAST ETHERNET SWITCH

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

A destructive RAM test is performed over the entire RAM space with the

exception of the space occupied by the boot image itself. The RAM test is quite

simple, and consists of writing a known pseudorandom value to each location in

the RAM and then reading the data back. If the data read is not equal to that

written, then the RAM is considered to be defective, and the system cannot

begin operation. (The RAM self-test is not intended to be an exhaustive device

test aimed at unconditionally detecting a faulty RAM, but merely a fast and

simple test for a gross go/no-go check.)

Additional self-test routines will be implemented in the bootstrap firmware code as

developed.

In addition to the self-test functions performed upon system start-up, the ELAN 1x100

operating firmware also performs numerous checks of its internal state during normal

system operation. If an unrecoverable error is detected, the ELAN 1x100 will output a

status code to the LED register, and then attempt to restart itself (and possibly the

entire system) via the internal watchdog reset facility. If the internal watchdog reset

output (as driven onto the ERST* pin) is connected to the global system reset, then the

ELAN 1x100 will reset the entire system; otherwise, the ERST* pin should be monitored

by an external system master to determine when the ELAN 1x100 is halted due to

some fatal error, and must be reset in order to continue.

In general, LEDs 6 and 7 (i.e., the most significant bits of the LED register) are intended

to be used to provide a general failure indication; LED 5 indicates whether the failure

occurred at self-test and initialization time, or whether the failure occurred during normal

operation; and the rest of the LEDs supply a diagnostic code that can be used to

identify the cause of the failure.

The LEDs also serve to output special codes during system initialization and during

normal operation. In this case, LEDs 6 and 7 will not be lighted. LED 5 indicates

whether the status pertains to system initialization or normal operation. Codes output

during system initialization indicate the index of the bootstrap tag being processed

during the initialization process, and range from 0 to the maximum number of bootstrap

tags in the boot image.

PM3351-SW Datasheet(PDF) 73 Page - PMC-Sierra, Inc