UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
281 of 1269
15.1 How to read this chapter
The following peripherals are not available on all parts, and the corresponding bit values
that select those functions in the SFSP registers are reserved:
•
Ethernet: available on LPC435x/3x only.
•
USB0: available on LPC435x/3x/2x only.
•
USB1: available on LPC435x/3x only.
•
LCD: available on LPC435x only.
15.2 Basic configuration
The SCU is configured as follows:
•
See
for clocking and power control.
•
The SCU is reset by the SCU_RST (reset # 9).
Remark:
Before using any of the multiplexed pins or the I2C0 pins
as inputs
, set the
corresponding pin configuration registers as follows:
•
Enable the input buffer by setting bit EZI to 1.
•
For high-frequency signals, disable the input glitch filter by setting bit ZIF to 1.
15.3 General description
The system control unit determines the function and electrical mode of most digital pins.
By default the digital function 0 with pull-up enabled is selected for all pins .
Remark:
Some pins support pin muxing of digital and analog functions. All analog I/Os for
the ADC and DAC are also pinned out on analog-only pads without pin muxing.
UM10503
Chapter 15: LPC43xx System Control Unit (SCU)/
IO configuration
Rev. 1.3 — 6 July 2012
User manual
Table 131. SCU clocking and power control
Base clock
Branch clock
Operating frequency
Clock to SCU register interface
BASE_M4_CLK
CLK_M4_SCU
up to 204 MHz