Motorola MVME177 manual SYSFAIL* Assertion/Negation, MPU Clock Speed Calculation

B

Debugger General Information

SYSFAIL* Assertion/Negation

Upon a reset/power-up condition the debugger asserts the VMEbus SYSFAIL* line (refer to the VMEbus specification). SYSFAIL* stays asserted if any of the following has occurred:

❏Confidence test failure

❏NVRAM checksum error

❏NVRAM low battery condition

❏Local memory configuration status

❏Self test (if system mode) has completed with error

❏MPU clock speed calculation failure

After debugger initialization is done and none of the above situations have occurred, the SYSFAIL* line is negated. This indicates to the user or VMEbus masters the state of the debugger. In a multi-computer configuration, other VMEbus masters could view the pertinent control and status registers to determine which CPU is asserting SYSFAIL*. SYSFAIL* assertion/negation is also affected by the ENV command.

MPU Clock Speed Calculation

The clock speed of the microprocessor is calculated and checked against a user definable parameter housed in NVRAM (refer to the CNFG command in the Commands Table). If the check fails, a warning message displays. The calculated clock speed is also checked against known clock speeds and tolerances.

B-10