3

Operating Instructions

RESET Switch S2

The recessed front panel RESET switch resets all onboard devices, and drives SYSRESET* if the board is system controller. The RESET switch may be disabled by software.

The VMEchip2 includes both a global and a local reset driver. When the chip operates as the VMEbus system controller, the reset driver provides a global system reset by asserting the VMEbus signal SYSRESET*. A SYSRESET* may be generated by the following:

RESET switch

Power up reset

Watchdog timeout

Control bit in the LCSR

SYSRESET* remains asserted for at least 200 msec, as required by the VMEbus specification.

Similarly, the VMEchip2 provides an input signal and a control bit to initiate a local reset operation. By setting a control bit, software can maintain a board in a reset state, disabling a faulty board from participating in normal system operation. The local reset driver is enabled even when the VMEchip2 is not the system controller. A local reset may be generated by:

RESET switch

Power up reset

Watchdog timeout

VMEbus SYSRESET*

Control bit in the GCSR

3-2

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Image 44
Motorola MVME177 manual Reset Switch S2