Control Registers; Compare High And Low Word Registers; Table 5-23 Control Registers - SMART Embedded Computing MVME2500 Installation & Use Manual

Memory Maps and Registers
5.6.2

Control Registers

Table 5-23 Control Registers

Tick Timer 0 Control Register - 0xFFC80202
REG Tick Timer 1 Control Register - 0xFFC80302
Tick Timer 2 Control Register - 0xFFC80402
Bit 15
Field
RSVD RSVD RSVD RSVD RSVD INTS
OPER R/W
RESET 0x0000
Field Description
ENC
COC
COVF
OVF
ENINT
CINT
INTS
RSVD
5.6.3

Compare 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.
104
14 13 12 11
Enable counter. When the bit is set, the counter increments. When the bit is cleared,
the counter does not increment.
Clear Counter on Compare. When the bit is set, the counter is reset to 0 when it
compares with the compare register. When the bit is cleared the counter is not reset.
Clear Overflow Bits. The overflow counter is cleared when a 1 is written to this bit.
Overflow Bits are the output of the overflow counter. It increments each time the tick
timer sends an interrupt to the local bus interrupter. The overflow counter is cleared by
writing a 1 to the COVF bit.
Enable Interrupt. When the bit is set, the interrupt is enabled. When the bit is cleared,
the interrupt is not enabled.
Clear Interrupt.
Interrupt Status.
Reserved for future implementation.
10 9 8 7 6 5 4 3
CINT ENINT OVF
MVME2500 Installation and Use (6806800L01S)
Memory Maps and Registers
2 1 0
RSVD COVF COC ENC