mc68hc11ea9 Freescale Semiconductor, Inc, mc68hc11ea9 Datasheet - Page 42

• Manufacturer Part Number: mc68hc11ea9
• Description: 8-bit Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

7.3 Real-Time Interrupt
TFLG2 — Timer Interrupt Flag 2
TOF — Timer Overflow Interrupt Flag
RTIF — Real-Time Interrupt Flag
PAOVF — Pulse Accumulator Overflow Interrupt Flag
PAIF — Pulse Accumulator Input Edge Interrupt Flag
Bits [3:0] — Not Implemented
42
RESET:
The real-time interrupt (RTI) function can generate interrupts at different fixed periodic rates. These
rates are a function of the MCU oscillator frequency and the value of the software-accessible control
bits, RTR1 and RTR0. These bits determine the rate at which interrupts are requested by the RTI sys-
tem. The RTI system is driven by an E divided by 2
of the timer prescaler. The RTR1 and RTR0 control bits select an additional division factor. RTI is set
to its fastest rate by default out of reset and can be changed at any time.
Refer to 7.2 Main Timer
If RTII enable bit is set, this flag is set and an interrupt is generated periodically at the rate determined
by the real-time interrupt rate (RTR[1:0]) bits in PACTL.
Refer to 7.4 Pulse Accumulator
Refer to 7.4 Pulse Accumulator
Always read zero
0 = No periodic interrupt has occurred since either the RTIF flag bit was last cleared or the RTII
1 = A periodic interrupt has occurred
RTR[1:0]
RTR[1:0]
0 0
0 1
1 0
1 1
enable bit was set
0 0
0 1
1 0
1 1
BIT 7
TOF
0
Frequency Possible
RTIF
Table 19 Real-Time Interrupt Rates (Period Length)
6
0
Period Length
Table 20 Real-Time Interrupt Rates (Frequency)
Freescale Semiconductor, Inc.
Maximum
Selected
2
2
2
2
2
2
2
2
For More Information On This Product,
13
14
15
16
13
14
15
16
PAOVF
E
E
E
E
E
E
E
E
5
0
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E = 1.0 MHz
PAIF
16.384 ms
32.768 ms
65.536 ms
E = 1.0 MHz
8.192 ms
122.070 Hz
4
0
61.035 Hz
30.518 Hz
15.258 Hz
13
—
rate clock compensated so that it is independent
3
0
Maximum Interrupt Frequency
E = 2.0 MHz
16.384 ms
32.768 ms
E = 2.0 MHz
4.096 ms
8.192 ms
244.141 Hz
122.070 Hz
Period Length
61.035 Hz
30.518 Hz
—
2
0
—
1
0
E = 3.0 MHz
MC68HC11EA9TS/D
10.923 ms
21.845 ms
2.731 ms
5.461 ms
E = 3.0 MHz
366.211 Hz
183.105 Hz
91.553 Hz
45.776 Hz
BIT 0
—
0
MC68HC11EA9
$1025