Motorola MVME1X7P - Manual (Page 74)

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Programming Issues
1
1. Set up Tick Timer:
2. Set up local bus interrupter:
Step Register and Address Action and Reference
1 Prescaler Control register
$FFF4004C If not already initialized by the debugger, initialize as
follows: Prescaler register = 256–Bclock (MHz). This
gives a 1 MHz clock to the tick timers. Bclock is the bus
clock rate, such as 25MHz.
256–25 = $E7.
2 Tick Timer 1
Compare register
$FFF40050 For periodic interrupts, set the Compare Register value =
Period (s). For example, if you want an interrupt every
millisecond, set the register value to 1000 ($3E8). Refer
to the
Tick Timer 1 Compare Register description in
Chapter 2.
3 Tick Timer 1
Counter register
$FFF40054 Write a zero to clear the register.
4 Tick Timer 1
Control register
$FFF40060 (8 bits) Write $07 to this register (set bits 0, 1, and 2). This
enables the Tick Timer 1 counter to increment, resets the
count to zero on compare, and clears the overflow
counter.
Step Register and Address Action and Reference
5 Vector Base register
$FFF40088 (8 of 32 bits) If not already initialized by the debugger, set Interrupt
Base register 0 by writing to bits 28-31. Refer to the
Vector Base Register description and to Table 2-4, Local
Bus Interrupter Summary, in Chapter 2.
6 Interrupt Level register 1
(bits 0-7)
$FFF40078 (8 of 32 bits) Write desired level of Tick Timer 1 interrupt to bits 0-2.
7 Local Bus Interrupter
Enable register
$FFF4006C (8 of 32 bits) Set bit 24 (ETIC1) to 1 to enable Tick Timer 1 interrupts.
8 I/O Control Register 1
$FFF40088 (8 of 32 bits) Write a 1 to bit 23 to enable interrupts from the
VMEchip2. A 0 masks all interrupts from the VMEchip2.