mc68hc05j1avp Freescale Semiconductor, Inc, mc68hc05j1avp Datasheet - Page 74

• Manufacturer Part Number: mc68hc05j1avp
• Description: M68hc05 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Multifunction Timer
Technical Data
74
NOTE:
RTIE — Real-Time Interrupt Enable Bit
TOFR — Timer Overflow Flag Reset Bit
RTIFR — Real-Time Interrupt Flag Reset Bit
RT1 and RT0 — Real-Time Interrupt Select Bits 1 and 0
Changing RT1 and RT0 when a COP timeout is imminent or uncertain
may cause a real-time interrupt request to be missed or an additional
real-time interrupt request to be generated. Clear the COP timer just
before changing RT1 and RT0.
1. At 2-MHz bus, 4-MHz XTAL, 0.5 s per cycle
RT1:RT0
This read/write bit enables real-time interrupts.
Writing a logic 1 to this write-only bit clears the TOF bit. TOFR always
reads as logic 0. Reset clears TOFR.
Writing a logic 1 to this write-only bit clears the RTIF bit. RTIFR
always reads as logic 0. Reset clears RTIFR.
These read/write bits select one of four RTI rates, as shown in
Table
watchdog, changing the real-time interrupt rate also changes the
counting rate of the COP watchdog. Reset sets RT1 and RT0.
Freescale Semiconductor, Inc.
0 0
0 1
1 0
1 1
For More Information On This Product,
1 = Real-time interrupts enabled
0 = Real-time interrupts disabled
8-1. Because the selected RTI output drives the COP
Table 8-1. Real-Time Interrupt Rate Selection
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2
2
2
2
17
of Cycles
14
15
16
Number
Multifunction Timer
to RTI
= 131,072
= 16,384
= 32,768
= 65,536
Period
16.4 ms
32.8 ms
65.5 ms
8.2 ms
RTI
(1)
2
to COP Reset
2
2
2
20
17
18
19
of Cycles
Number
= 1,048,576
= 131,072
= 262,144
= 524,288
MC68HC05J1A — Rev. 3.0
COP Timeout
131.1 ms
262.1 ms
524.3 ms
Period
65.5 ms
MOTOROLA
(1)