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AMX 68000 Target Guide
5.3.4 MC68901 Clock Driver
The AMX clock driver for the Motorola MC68901 Multi-Function Peripheral is ready for
use on the Motorola MVME133 VMEmodule board. It is configured to use timer A
operating at 1 KHz (1 ms period). Source code for this AMX clock driver is provided in
file CH68901T.C.
You must compile clock source module CH68901T.C and link the resulting object module
with the rest of your AMX application.
To use the AMX MC68901 clock driver, you must create a clock ISP root as described in
Chapter 4.3. Simply check the box next to the MC68901 clock ISP on the list provided
via the Prebuilt Clock ISPs... button.
Your Target Configuration Module will include a clock ISP root named _ch68901clk.
The clock driver's initialization procedure will install the pointer to this clock ISP into the
AMX Vector Table. On the Motorola MVME133 VMEmodule board, the pointer is
installed into the entry for interrupt vector number 96+n ($60+n) where n is $0D for timer
A (or 8 for timer B, 5 for timer C or 4 for timer D).
Clock driver module CH68901T.C includes the clock initialization procedure
chclockinit and the clock shutdown procedure chclockexit. Insert procedure
chclockinit into the list of Restart Procedures provided in your System Configuration
Module at the point at which you wish the clock to be enabled during the launch. If you
intend to launch AMX for temporary execution, insert chclockexit into the list of Exit
Procedures at the point at which you wish the clock to be disabled during the shutdown.
Porting the MC68901 Clock Driver
If you wish to use a different MC68901 timer, say B (or C or D), or change the timer
frequency or use a different AMX vector number, you must edit the definitions in source
file CH68901T.C and recompile the module. Edit instructions are included in the file.