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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
70 of 571
NXP Semiconductors
UM10316
Chapter 5: LPC29xx Power Management Unit (PMU)
4.3 PMU clock configuration register for output branches
Each generated output clock from the PMU has a configuration register.
[1]
Tied off to logic LOW for some branch clocks. All writes are ignored for those with tied bits.
[2]
Tied off to logic HIGH for some branch clocks. All writes are ignored for those with tied bits.
4.4 Status register for output branch clock
Like the configuration register, each generated output clock from the PMU has a status
register. When the configuration register of an output clock is written to the value of the
actual hardware signals may not be updated immediately. This may be due to the auto or
wake-up mechanism. The status register shows the current value of these signals.
2
BASE2_STAT
R
1*
Indicator for BASE_PCR_CLK
1
BASE1_STAT
R
1*
Indicator for BASE_SYS_CLK
0
BASE0_STAT
R
1*
Indicator for BASE_SAFE_CLK
Table 52.
BASE_STAT register bit description (BASE_STAT, address 0xFFFF A004)
* = reset value
Bit
Symbol
Access
Value
Description
Table 53.
CLK_CFG_XXX register bit description (CLK_CFG_SAFE to CLK_CFG_USB_CLK,
addresses 0xFFFF A100 to 0xFFFF AD00)
* = reset value
Bit
Symbol
Access
Value
Description
31 to 3
reserved
R
-
Reserved; do not modify. Read as logic 0
2
WAKEUP
R/W
1
The branch clock is ’wake-up enabled’. When
the PD bit in the Power Mode register (see
) is set, and clocks which are
wake-up enabled are switched off. These
clocks will be switched on if a wake-up event is
detected or if the PD bit is cleared. If register bit
AUTO is set, the AHB disable protocol must
complete before the clock is switched off.
0*
PD bit has no influence on this branch clock
1
AUTO
R/W
1
Enable auto (AHB disable mechanism). The
PMU initiates the AHB disable protocol before
switching the clock off. This protocol ensures
that all AHB transactions have been completed
before turning the clock off
0*
No AHB disable protocol is used.
0
RUN
R/W
1*
The WAKEUP, PD (and AUTO) control bits
determine the activation of the branch clock. If
register bit AUTO is set the AHB disable
protocol must complete before the clock is
switched off.
0
Branch clock switched off