Motorola MVME2400 manual ABT S1, RST S2

MVME240x

ABT (S1)

When activated by software, the Abort switch, ABT, can generate an interrupt signal from the base board to the processor at a user- programmable level. The interrupt is normally used to abort program execution and return control to the debugger firmware located in the MVME240x Flash memory. The interrupt signal reaches the processor module via ISA bus interrupt line IRQ8∗. The signal is also available from the general purpose I/O port, which allows software to poll the Abort switch after an IRQ8* interrupt and verify that it has been pressed.

The interrupter connected to the ABT switch is an edge-sensitive circuit, filtered to remove switch bounce.

RST (S2)

The Reset switch, RST, resets all onboard devices and causes HRESET* to be asserted in the MPC603 or MPC604. It also drives a SYSRESET* signal if the MVME240x VME processor module is the system controller.

The Universe ASIC includes both a global and a local reset driver. When the Universe operates as the VMEbus system controller, the reset driver provides a global system reset by asserting the VMEbus signal SYSRESET*. A SYSRESET* signal may be generated by the RESET switch, a power-up reset, a watchdog timeout, or by a control bit in the Miscellaneous Control Register (MISC_CTL) in the Universe ASIC. SYSRESET* remains asserted for at least 200 ms, as required by the VMEbus specification.

Similarly, the Universe ASIC supplies 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 Universe ASIC is not system controller. Local resets may be generated by the RST switch, a power-up reset, a watchdog timeout, a VMEbus SYSRESET*, or a control bit in the MISC_CTL register.

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