MSC8113 Reference Manual, Rev. 0
7-2
Freescale Semiconductor
Clocks
The Ethernet interface has two clock zones:
— The serial interface:
•
MII mode. The receiver clock is
ETHRX_CLK
; the transmitter clock is
ETHTX_CLK
.
•
RMII mode. The receiver and transmitter are clocked by
ETHREF_CLK
.
•
SMII mode. The receiver and transmitter are clocked by
ETHCLOCK
.
— Local bus interface is clocked by the BUSES_CLOCK.
7.1 Clock Generation
The
CLKOUT
signal, the internal CORE_CLOCK, and the BUSES_CLOCK are generated as a
function of the
CLKIN
signal, guaranteeing minimum skew between the
CLKOUT
and
BUSES_CLOCK of all the MSC8113 devices. Figure 7-1 shows the MSC8113 clock scheme.
CLKIN
is generated by an external oscillator and is fed to the SPLL that divides and multiplies its
frequency according to the PLLRDF, PLLFDF, PLLODF, and the BUSDF factors as configured
by the System Clock Mode Status Register
(
SCMSR) (see Section 7.4, Clocks Programming
Model). The PLLPDF field divides the frequency by 1 or 2. The PLL VCO clock is generated by
multiplying the PLL predivider clock by: 2
×
PLLFDF
×
PLLODF
×
BUSDF. The PLL output
clock is generated by dividing the PLL VCO clock by: 2
×
PLLODF. The SCMSR[BUSDF] bit
value controls the frequency ratio between the BUSES_CLOCK and the CORES_CLOCK. The
CLKOUT
is typically the system bus clock or the local bus clock.
In Figure 7-2, the CORES_CLOCK and BUSES_CLOCK frequency ratio is 1:3.
Figure 7-1. CORES_CLOCK, BUSES_CLOCK, and CLKCOUT Generation
Figure 7-2. CORES_CLOCK, BUSES_CLOCK, and CLKOUT Example
BUSES_CLOCK
CLKOUT
PLLRDF: PLL input clock division factor
PLLFDF: PLL Feadback division factor
PLLODF: PLL output clock division factor
BUSDF: CLOCK_BUSES division factor
CORES_CLOCK
CLKIN
SPLL
Division by
PLLRDF
Division by
2
×
PLLODF
Division
BUSDF
by
Division by
PLLFDF
PFD and
Division
BUSDF
by
VCO
CORES_CLOCK
BUSES_CLOCK
CLKOUT
Содержание MSC8113
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Страница 56: ...MSC8113 Reference Manual Rev 0 1 28 Freescale Semiconductor MSC8113 Overview ...
Страница 76: ...MSC8113 Reference Manual Rev 0 2 20 Freescale Semiconductor SC140 Core Overview ...
Страница 134: ...MSC8113 Reference Manual Rev 0 4 30 Freescale Semiconductor System Interface Unit SIU ...
Страница 168: ...MSC8113 Reference Manual Rev 0 6 18 Freescale Semiconductor Boot Program ...
Страница 180: ...MSC8113 Reference Manual Rev 0 7 12 Freescale Semiconductor Clocks ...
Страница 260: ...MSC8113 Reference Manual Rev 0 8 80 Freescale Semiconductor Memory Map ...
Страница 300: ...MSC8113 Reference Manual Rev 0 9 40 Freescale Semiconductor Extended Core ...
Страница 304: ...MSC8113 Reference Manual Rev 0 10 4 Freescale Semiconductor MQBus and M2 Memory ...
Страница 308: ...MSC8113 Reference Manual Rev 0 11 4 Freescale Semiconductor SQBus ...
Страница 544: ...MSC8113 Reference Manual Rev 0 16 46 Freescale Semiconductor Direct Memory Access DMA Controller ...
Страница 590: ...MSC8113 Reference Manual Rev 0 17 46 Freescale Semiconductor Interrupt Processing ...
Страница 614: ...MSC8113 Reference Manual Rev 0 18 24 Freescale Semiconductor Debugging ...
Страница 622: ...MSC8113 Reference Manual Rev 0 19 8 Freescale Semiconductor Internal Peripheral Bus IPBus ...
Страница 724: ...MSC8113 Reference Manual Rev 0 21 32 Freescale Semiconductor UART ...
Страница 920: ...MSC8113 Reference Manual Rev 0 25 150 Freescale Semiconductor Ethernet Controller ...
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Страница 1172: ...MSC8113 Reference Manual Rev 0 C 62 Freescale Semiconductor MSC8113 Boot Code ...
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