Motorola MVME1X7P manual To the Tick Timer 1 Compare Register description

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Programming Issues

1.Set up Tick Timer:

Step	Register and Address	Action and Reference
1	Prescaler Control register	If not already initialized by the debugger, initialize as
	$FFF4004C	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	For periodic interrupts, set the Compare Register value =
	Compare register	Period (s). For example, if you want an interrupt every
	$FFF40050	millisecond, set the register value to 1000 ($3E8). Refer
		to the Tick Timer 1 Compare Register description in
		Chapter 2.
3	Tick Timer 1	Write a zero to clear the register.
	Counter register
	$FFF40054
4	Tick Timer 1	Write $07 to this register (set bits 0, 1, and 2). This
	Control register	enables the Tick Timer 1 counter to increment, resets the
	$FFF40060 (8 bits)	count to zero on compare, and clears the overflow
		counter.

2.Set up local bus interrupter:

Step	Register and Address	Action and Reference
5	Vector Base register	If not already initialized by the debugger, set Interrupt
	$FFF40088 (8 of 32 bits)	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	Write desired level of Tick Timer 1 interrupt to bits 0-2.
	(bits 0-7)
	$FFF40078 (8 of 32 bits)
7	Local Bus Interrupter	Set bit 24 (ETIC1) to 1 to enable Tick Timer 1 interrupts.
	Enable register
	$FFF4006C (8 of 32 bits)
8	I/O Control Register 1	Write a 1 to bit 23 to enable interrupts from the
	$FFF40088 (8 of 32 bits)	VMEchip2. A 0 masks all interrupts from the VMEchip2.

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