UM10850
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User manual
Rev. 2.4 — 13 September 2016
65 of 464
NXP Semiconductors
UM10850
Chapter 4: LPC5410x System configuration (SYSCON)
4.5.56 Asynchronous APB clock control clear register
Writing a 1 to a bit position in ASYNCAPBCLKCTRLCLR clears the corresponding
position in ASYNCAPBCLKCTRL. This is a write-only register. For bit assignments, see
.
4.5.57 Asynchronous clock source select register A
This register selects a potential clock for the asynchronous APB peripherals from among
several clock sources. The clock selected becomes one of the inputs to the asynchronous
clock source select register B (see
), which selects the final clock source for the
asynchronous APB clock.
Remark:
Note that this selection is internally synchronized: the clock being switched from
and the clock being switched to must both be running and have occurred in specific states
before the selection actually changes.
4.5.58 Asynchronous clock source select register B
This register selects the clock source for the asynchronous APB clock.
Remark:
Note that this selection is internally synchronized: the clock being switched from
and the clock being switched to must both be running and have occurred in specific states
before the selection actually changes.
Table 95.
Asynchronous APB clock control clear register (ASYNCAPBCLKCTRLCLR, address 0x4008 0018) bit
description
Bit
Symbol
Description
Reset value
31:0
ACLK_CLR
Writing ones to this register clears the corresponding bit or bits in the
ASYNCAPBCLKCTRL register, if they are implemented.
Bits that do not correspond to defined bits in ASYNCAPBCLKCTRL are reserved and
only zeroes should be written to them.
-
Table 96.
Asynchronous clock source select register A (ASYNCAPBCLKSELA, address
0x4008 0020) bit description
Bit
Symbol
Value
Description
Reset value
1:0
SEL
Clock source for asynchronous clock source selector A
0
0x0
IRC Oscillator
0x1
Watchdog oscillator
0x2
Reserved
0x3
Reserved
31:2
-
-
Reserved
-