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
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 ...
Page 262: ...9 36 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
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 ...
Page 352: ...13 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 394: ...14 42 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 426: ...15 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 530: ...17 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 660: ...22 28 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 708: ...24 24 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 748: ...27 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 846: ...31 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 914: ...35 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 948: ...36 34 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
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 ...
Page 1086: ...Glossary 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA ...
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