MOTOROLA
Chapter 15. Clocks and Power Control
15-11
Part IV. Hardware Interface
Figure 15-6. Low-power dividers for GCLKx
The high frequency is generated by using the DFNH Þeld in the SCCR and it is used in
normal high and doze high mode. The low frequency is generated using the DFNL Þeld in
the SCCR and it is used in normal low and doze low mode. The DFNH and DFNL dividers
are cleared by HRESET, and therefore GCLKx defaults to VCOOUT.
The frequency for the GCLKx system clock is:
When GCLKx is divided, its duty-cycle is modiÞed. One phase remains the same while the
other stretches out. GCLKx no longer has a 50% duty cycle when the division factor is
greater than 1, as shown in Figure 15-7.
Figure 15-7. Divided System Clocks (GCLKx) Timing Diagram
15.3.1.2 Memory Controller and External Bus Clocks (GCLK1_50,
GCLK2_50, CLKOUT)
The MPC860 provides the capability to run the external bus and memory controller at a
lower frequency than the internal modules. This capability is provided by the external bus
frequency dividers. The external bus clocks GCLK1_50 and GCLK2_50 are derived from
GCLK1 and GCLK2, as determined by the SCCR[EBDF]. SCCR[EBDF] is cleared by
HRESET, and thus GCLK1_50 and GCLK2_50 default to GCLK1 and GCLK2. The
DFNH divider
DFNL divider
VCOout
DFNH
Low Power mode
Gclk1
DFNL
2:1
MUX
GCLKx
freq
VCOOUT
freq
2
DFNH
(
)
or 2
DFNL
1
+
(
)
----------------------------------------------------------------
=
GCLK1 Divided by 1
GCLK2 Divided by 1
GCLK1 Divided by 2
GCLK2 Divided by 2
GCLK1 Divided by 4
GCLK2 Divided by 4
Содержание MPC860 PowerQUICC
Страница 3: ...MPC860UM AD 07 98 REV 1 MPC860 PowerQUICC ª UserÕs Manual ...
Страница 36: ...xxxvi MPC860 PowerQUICC UserÕs Manual MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Страница 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Страница 88: ...1 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Страница 114: ...3 16 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Страница 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Страница 262: ...9 36 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Страница 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Страница 320: ...12 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Страница 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Страница 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Страница 352: ...13 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Страница 394: ...14 42 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Страница 426: ...15 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Страница 530: ...17 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Страница 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Страница 660: ...22 28 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Страница 708: ...24 24 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Страница 748: ...27 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Страница 846: ...31 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Страница 914: ...35 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Страница 948: ...36 34 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Страница 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Страница 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Страница 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Страница 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Страница 1086: ...Glossary 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA ...
Страница 1106: ......