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MPC860 PowerQUICC UserÕs Manual
MOTOROLA
Part V. The Communications Processor Module
18.2.4 Timer Initialization Examples
The following two initialization sequences program timer 2 to generate an interrupt every
10
m
s. The Þrst sequence uses timer 2 alone, while the second example uses timers 1 and 2
in cascaded mode. Assuming a 25-MHz general system clock, an interrupt should be
generated every 250 system clocks.
1. Set TGCR = 0x0000 to reset timer 2.
2. Set TMR2 = 0x001A to set the prescaler to divide by 1 and the clock source to the
general system clock. This value also enables an interrupt when the timer reaches
the reference count and immediately clears (restarts) the TCN for the next interrupt.
3. Set TCN2 = 0x0000 to clear the timer 2 counter (default).
4. Set TRR2 = 0x00FA to initialize the timer 2 reference value to 250.
5. Write TER2 = 0xFFFF to clear TER2 of any previous events.
6. Set CIMR = 0x0004_0000 to enable timer 2 interrupts in the CPIC and initialize the
CICR.
7. Set TGCR = 0x0010 to enable timer 2 to begin counting.
To implement the same function with a 32-bit timer using timers 1 and 2, follow these steps:
1. Set TGCR = 0x0080. Cascade timers 1 and 2 and put them in reset state.
2. Set TMR2 = 0x001A to set the prescaler to divide by 1 and the clock source to the
general system clock. This value also enables an interrupt when the timer reaches
the reference count and immediately clears the TCN for the next interrupt.
3. Set TMR1 = 0x0000. Enable timer 1 to use the timer 2 output as its input
(TMR1[ICLK] = 0b00).
4. Set TCN1 = 0x0000 and TCN2 = 0x0000. Initialize the count of the combined timers
1 and 2 to zero (TMR1 default) by using one 32-bit data move to TCN1.
5. Set TRR1 = 0x0000 and TRR2 = 0x00FA. Initialize the reference value of the
combined timers 1 and 2 to 250 by using one 32-bit data move to TRR1.
6. Write TER2 = 0xFFFF to clear TER2 of any previous events.
7. Set CIMR = 0x0004_0000 to enable timer 2 interrupts in the CPIC and initialize the
CICR.
8. Set TGCR = 0x0091 to enable timers 1 and 2 to begin counting in cascaded mode.
Summary of Contents for MPC860 PowerQUICC
Page 3: ...MPC860UM AD 07 98 REV 1 MPC860 PowerQUICC ª UserÕs Manual ...
Page 36: ...xxxvi MPC860 PowerQUICC UserÕs Manual MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 88: ...1 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 114: ...3 16 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
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Page 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 320: ...12 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Page 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
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Page 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Page 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
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