
Clock Module
Freescale Semiconductor
7-11
where
f
sys
is the core frequency. The allowable range of values for the PFDR is 88 to 135, resulting in a
frequency multiplication factor range of 11 to 16.88 times the input reference frequency (typically
16 MHz).
The PFDR can only be modified while the device is in limp mode, which is entered by setting the
MISCCR[LIMP] bit. After the PFDR register has been changed, re-enter normal mode by clearing the
MISCCR[LIMP] bit. The PLL then begins to acquire lock accordingly on the new frequency.
7.3.4
System Clock Modes
The system clock source is determined during reset. By default the PLL is placed in crystal reference mode
and generates a core/bus frequency of 180/60 MHz. This default mode can be overridden by asserting the
RCON pin. See
Chapter 9, “Chip Configuration Module (CCM),”
for more information on overriding the
default configuration during reset.
shows the clock-out frequency to clock-in frequency relationships for the possible system clock
modes. Refer to
Section 7.1.3, “Modes of Operation”
for details on each mode.
7.3.5
Clock Operation During Reset
This section describes the reset operation of the PLL. Power-on reset and normal reset are described.
7.3.5.1
Power-On Reset (POR)
After V
DDPLL
and the input clock are within specification, the PLL is held in reset for at least 10 input
clock cycles to initialize the PLL. The reset configuration signals are used to select the multiply factor of
the PLL and the reset state of the PLL registers. While in reset, the PLL input clock is output to the device.
After RESET is de-asserted, PLL output clocks are generated; however, until the MISCCR[PLLLOCK]
bit is set the PLL output clock frequencies are not stable and not within specification. The
MISCCR[PLLLOCK] bit is set after RESET has negated for a minimum of 1 ms. When this bit is set, the
PLL is in frequency lock.
Table 7-7. Clock Out and Clock In Relationships
System Clock Mode
PLL Options
1
1
f
ref
= input reference frequency = 16 MHz
PFDR ranges from 88 to 135
MISCCR[LPDIV] ranges from 0 to 15
Cross-Reference
Normal PLL clock mode
Section 7.1.3.1, “Normal PLL Mode with
Crystal Reference”
and
“Normal PLL Mode with External Reference”
Limp mode
Section 7.1.3.3, “Input Clock (Limp) Mode”
f
sys
f
ref
PFDR
8
----------------
⎝
⎠
⎛
⎞
×
=
f
sys
f
ref
2
MISCCR LPDIV
[
]
-----------------------------------------
=
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
Страница 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 902: ...Register Memory Map Quick Reference A 26 Freescale Semiconductor MCF5329 Reference Manual Rev 3...