Clocks and Power Control
MPC885 PowerQUICC Family Reference Manual, Rev. 2
14-8
Freescale Semiconductor
the design is performed; if potential manufacturing downtime due to redesign of crystal circuits is
unacceptable, a canned oscillator circuit should be used instead.
Figure 14-3. Crystal Circuit Examples
14.3
Clock Signals
The MPC885 uses the following clocks, summarized in
Table 14-4
. These clocks are described in the
following three sections, grouped by their different sources.
.
Table 14-4. Functionality Summary of the Clocks
Clock Description
GCLK1C/GCLK2C
Basic clocks supplied to the core, the data and instruction caches, and MMUs
GCLK1/GCLK2
Basic clocks supplied to the SIU, clock module, CP, and most other features in the CPM
GCLK1_50/GCLK2_50
Optionally divided versions of GCLK1/GCLK2 that clock the GPCM and UPM in the
memory controller and provide the CLKOUT output for the external bus
UTPCLK
Clocks the Utopia Module
BRGCLK
Clocks the four baud rate generators and the memory controller refresh timer. This allows
the serial ports to operate at a fixed frequency and the memory refresh to continue at a
uniform rate even when the rest of the MPC885 is operating at a reduced frequency.
SYNCCLK
Used by the serial synchronization circuitry in the serial ports of the CPM, and includes the
SI, SCC, and SMCs. SYNCCLK performs the function of synchronizing externally
generated clocks before they are used internally. SYNCCLK allows the SI, SCC, and SMCs
to continue operating at a fixed frequency.
CLKOUT
Clock out is an external clock signal used to drive other devices, and thus provide the ability
to operate synchronously with those devices. Equivalent to the internal GCLK2_50 signal.
TMBCLK
Clocks the time base and decrementer
PITCLK
Clocks the periodic interrupt timer
XTAL
EXTAL
A5
A4
OSCM
Crystal = 10 MHz
C1
R2
R1
C2
R1=10M
Ω
, R2=1K
Ω
, C1=47pf, C2=56pf
Содержание PowerQUICC MPC870
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Страница 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Страница 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Страница 192: ...MPC885 Instruction Set MPC885 PowerQUICC Family Reference Manual Rev 2 5 22 Freescale Semiconductor ...
Страница 242: ...Instruction and Data Caches MPC885 PowerQUICC Family Reference Manual Rev 2 7 30 Freescale Semiconductor ...
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Страница 440: ...Clocks and Power Control MPC885 PowerQUICC Family Reference Manual Rev 2 14 24 Freescale Semiconductor ...
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Страница 606: ...SDMA Channels and IDMA Emulation MPC885 PowerQUICC Family Reference Manual Rev 2 19 20 Freescale Semiconductor ...
Страница 738: ...SCC Asynchronous HDLC Mode and IrDA MPC885 PowerQUICC Family Reference Manual Rev 2 25 16 Freescale Semiconductor ...
Страница 780: ...SCC Ethernet Mode MPC885 PowerQUICC Family Reference Manual Rev 2 27 24 Freescale Semiconductor ...
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Страница 882: ...Universal Serial Bus USB MPC885 PowerQUICC Family Reference Manual Rev 2 31 34 Freescale Semiconductor ...
Страница 944: ...Parallel I O Ports MPC885 PowerQUICC Family Reference Manual Rev 2 34 26 Freescale Semiconductor ...
Страница 956: ...CPM Interrupt Controller MPC885 PowerQUICC Family Reference Manual Rev 2 35 12 Freescale Semiconductor ...
Страница 1004: ...Buffer Descriptors and Connection Tables MPC885 PowerQUICC Family Reference Manual Rev 2 37 30 Freescale Semiconductor ...
Страница 1022: ...ATM Parameter RAM MPC885 PowerQUICC Family Reference Manual Rev 2 38 18 Freescale Semiconductor ...
Страница 1068: ...ATM Pace Control MPC885 PowerQUICC Family Reference Manual Rev 2 40 22 Freescale Semiconductor ...
Страница 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Страница 1120: ...AAL2 Implementation MPC885 PowerQUICC Family Reference Manual Rev 2 44 30 Freescale Semiconductor ...
Страница 1162: ...Fast Ethernet Controller FEC MPC885 PowerQUICC Family Reference Manual Rev 2 45 40 Freescale Semiconductor ...
Страница 1172: ...SEC Lite Overview MPC885 PowerQUICC Family Reference Manual Rev 2 46 8 Freescale Semiconductor ...
Страница 1176: ...SEC Lite Address Map MPC885 PowerQUICC Family Reference Manual Rev 2 47 4 Freescale Semiconductor ...
Страница 1214: ...SEC Lite Execution Units MPC885 PowerQUICC Family Reference Manual Rev 2 48 38 Freescale Semiconductor ...
Страница 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Страница 1313: ...MPC885 PowerQUICC Family Reference Manual Rev 2 Freescale Semiconductor B 1 Appendix B Serial Communications Performance TBD ...
Страница 1314: ...Serial Communications Performance MPC885 PowerQUICC Family Reference Manual Rev 2 B 2 Freescale Semiconductor ...
Страница 1320: ...Register Quick Reference Guide MPC885 PowerQUICC Family Reference Manual Rev 2 C 6 Freescale Semiconductor ...
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Страница 1384: ...Serial ATM Scrambling Reception and SI Programming MPC885 PowerQUICC Family Reference Manual Rev 2 H 6 Freescale Semiconductor ...
Страница 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...