Emerson MVME2500 manual Compare High and Low Word Registers, Compare High Word Registers

Memory Maps and Registers

5.6.3Compare High and Low Word Registers

The tick timer counter is compared to the Compare Register. When the values are equal, the tick timer interrupt is asserted and the overflow counter increments. If the clear-on-compare mode is enable, the counter is also cleared. For periodic interrupts, this equation should be used to calculate the compare value for a specific period (T):

Compare register value=T (us)

When programming the tick timer for periodic interrupt, the counter should be cleared to zero by software and then enabled. If the counter does not initially start at zero, the time to the first interrupt may be longer or shorter than expected. Note that the rollover time for the counter is 71.6 minutes.

Since the processor is 16-bits and the tick timer is 32-bits, the compare register was split in half. Accessing the whole register will require two transactions.

Table 5-24 Compare High Word Registers

	Tick Timer 0 Compare Value High Word							- 0xFFC80204
	Tick Timer 1 Compare Value High Word							- 0xFFC80304
REG	Tick Timer 2 Compare Value High Word							- 0xFFC80404
Bit	15	14	13	12	11	10	9		8	7	6	5	4	3	2	1	0
Field	TickTimer Compare Value High Word (16-bits)
OPER	R/W
RESET	0x0000

Table 5-25 Compare Low Word Registers

	Tick Timer 0 Compare Value Low Word						- 0xFFC80206
	Tick Timer 1 Compare Value Low Word						- 0xFFC80306
REG	Tick Timer 2 Compare Value Low Word						- 0xFFC80406
Bit	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Field	TickTimer Compare Value Low Word (16-bits)
OPER	R/W
RESET	0x0000

100 MVME2500 Installation and Use (6806800L01H)