Software Initialization

Software Initialization

Most functions that have been done with switches or jumpers on other modules are done by setting control registers on the MVME197LE. At power- up or reset, the FLASH memory that contains the 197Bug debugging package sets up the default values of many of these registers.

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Specific programming details may be determined by study of the MC88110 Second Generation RISC Microprocessor User’s Manual. Then check the details of all the MVME197LE onboard registers as given in the MVME197LE, MVME197DP, and MVME197SP Single Board Computers Programmer’s Reference Guide.

Multi-MPU Programming Considerations

Good programming practice dictates that only one MPU at a time have control of the MVME197LE control registers.Of particular note are:

registers that modify the address map; registers that require two cycles to access; and VMEbus interrupt request registers.

Local Reset Operation

Local reset (LRST) is a subset of system reset (SRST). Local reset can be generated five ways: by expiration of the watchdog timer, by pressing the front panel RESET switch (if the system controller function is disabled), by asserting a bit in the board control register in the GSCR, by SYSRESET*, or by power-up reset.

Note

The GCSR allows a VMEbus master to reset the local bus. This feature is very dangerous and should be used with caution. The local reset feature is a partial system reset, not

acomplete system reset such as power-up reset or SYSRESET*. When the local bus reset signal is asserted, a local bus cycle may be aborted. The VMEchip2 is connected to both the local peripheral bus and the VMEbus and if the aborted cycle is bound for the VMEbus, erratic operation may result. Communications between the local processor and a VMEbus master should use interrupts or mailbox locations; reset should not be used in normal communications. Reset should be used only when the local processor is halted or the local peripheral bus is hung and reset is the last resort.

MVME197LE/D2

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Motorola MVME197LE user manual Software Initialization, Multi-MPU Programming Considerations, Local Reset Operation