lpc1224 NXP Semiconductors, lpc1224 Datasheet - Page 24

• Manufacturer Part Number: lpc1224
• Description: Lpc122x 32-bit Arm Cortex-m0 Microcontroller; Up To 128 Kb Flash And 8 Kb Sram
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC122X
Objective data sheet
Fig 5.
watchdog oscillator
system oscillator
IRC oscillator
IRC oscillator
LPC122x clocking generation block diagram
7.18.1.1 Internal RC oscillator
7.18.1.2 System oscillator
SYSPLLCLKSEL
The IRC may be used as the clock source for the WDT, and/or as the clock that drives the
PLL and subsequently the CPU. The nominal IRC frequency is 12 MHz. The IRC is
trimmed to 1 % accuracy over the entire voltage and temperature range.
Upon power-up or any chip reset, the LPC122x use the IRC as the clock source. Software
may later switch to one of the other available clock sources.
The system oscillator can be used as the clock source for the CPU, with or without using
the PLL.
(main clock select)
SYSTEM PLL
MAINCLKSEL
All information provided in this document is subject to legal disclaimers.
Rev. 1.1 — 21 February 2011
main clock
watchdog oscillator
watchdog oscillator
system oscillator
IRC oscillator
IRC oscillator
(CLKOUT clock update enable)
(WWDT clock select)
3
7
DIVIDER
CLKOUTUEN
CLOCK
WDCLKSEL
RTC oscillator 1 Hz delayed clock
RTC oscillator 1 kHz clock
RTC oscillator 1 Hz clock
system clock
32-bit ARM Cortex-M0 microcontroller
SYSAHBCLKCTRL[1:31]
DIVIDER
DIVIDER
DIVIDER
CLOCK
CLOCK
CLOCK
(AHB clock enable)
31
RTCOSCCTRL
peripheral clocks
(SSP, UART0, UART1)
peripheral clocks
(IOCONFIG glitch filter)
DIVIDER
CLOCK
AHB clock 0
(system)
LPC122x
© NXP B.V. 2011. All rights reserved.
RTC
AHB clocks
1 to 31
(memories
and peripherals)
CLKOUT pin
WWDT
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