
UM10800
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© NXP Semiconductors N.V. 2016. All rights reserved.
User manual
Rev. 1.2 — 5 October 2016
29 of 487
NXP Semiconductors
UM10800
Chapter 5: LPC82x System configuration (SYSCON)
Table 95 “PIO0_9 register (PIO0_9, address 0x4004 4034) bit description”
Table 79 “Pin enable register 0 (PINENABLE0, address 0x4000 C1C0) bit description”
Table 26 “System oscillator control register (SYSOSCCTRL, address 0x4004 8020) bit
description”
5.4 Pin description
The SYSCON inputs and outputs are assigned to external pins through the switch matrix.
See
Section 7.3.1 “Connect an internal signal to a package pin”
to assign the CLKOUT
function to a pin.
See
to enable the clock input, the oscillator pins, and the external reset
input.
5.5 General description
5.5.1 Clock generation
The system control block generates all clocks for the chip. Only the low-power oscillator
used for wake-up timing is controlled by the PMU. Except for the USART clock and the
clock to configure the glitch filters of the digital I/O pins, the clocks to the core and
peripherals run at the same frequency. The maximum system clock frequency is 30 MHz.
See
Remark:
The main clock frequency is limited to 100 MHz.
Table 20.
SYSCON pin description
Function
Direction Pin
Description
SWM register
Reference
CLKOUT
O
any
CLKOUT clock output.
PINASSIGN8
CLKIN
I
PIO0_1/ACMP_I2/CLKIN
External clock input to the system
PLL. Disable the ACMP_I2 function
in the PINENABLE register.
PINENABLE0
XTALIN
I
PIO0_8/XTALIN
Input to the system oscillator.
PINENABLE0
XTALOUT O
PIO0_9/XTALOUT
Output from the system oscillator.
PINENABLE0
RESET
I
RESET/PIO0_5
External reset input
PINENABLE0