LPC2220 PHILIPS [NXP Semiconductors], LPC2220 Datasheet - Page 28

• Manufacturer Part Number: LPC2220
• Description: 16/32-bit ARM microcontrollers; flashless with 64 kB, with 10-bit ADC and external memory interface
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14061
Product data sheet
6.20.3 Reset and wake-up timer
6.20.4 External interrupt inputs
6.20.5 Memory mapping control
6.20.6 Power control
Reset has two sources on the LPC2210/2220: the RESET pin and watchdog reset. The
RESET pin is a Schmitt trigger input pin with an additional glitch filter. Assertion of chip
Reset by any source starts the wake-up timer (see wake-up timer description below),
causing the internal chip reset to remain asserted until the external Reset is de-asserted,
the oscillator is running, a fixed number of clocks have passed, and the on-chip circuitry
has completed its initialization.
When the internal Reset is removed, the processor begins executing at address 0, which
is the Reset vector. At that point, all of the processor and peripheral registers have been
initialized to predetermined values.
The wake-up timer ensures that the oscillator and other analog functions required for chip
operation are fully functional before the processor is allowed to execute instructions. This
is important at power on, all types of Reset, and whenever any of the aforementioned
functions are turned off for any reason. Since the oscillator and other functions are turned
off during Power-down mode, any wake-up of the processor from Power-down mode
makes use of the wake-up timer.
The wake-up timer monitors the crystal oscillator as the means of checking whether it is
safe to begin code execution. When power is applied to the chip, or some event caused
the chip to exit Power-down mode, some time is required for the oscillator to produce a
signal of sufficient amplitude to drive the clock logic. The amount of time depends on
many factors, including the rate of V
and its electrical characteristics (if a quartz crystal is used), as well as any other external
circuitry (e.g. capacitors), and the characteristics of the oscillator itself under the existing
ambient conditions.
The LPC2210/2220 includes up to nine edge or level sensitive External Interrupt Inputs as
selectable pin functions. When the pins are combined, external events can be processed
as four independent interrupt signals. The External Interrupt Inputs can optionally be used
to wake up the processor from Power-down mode.
The Memory Mapping Control alters the mapping of the interrupt vectors that appear
beginning at address 0x0000 0000. Vectors may be mapped to the bottom of the BANK0
external memory, or to the on-chip static RAM. This allows code running in different
memory spaces to have control of the interrupts.
The LPC2210/2220 supports two reduced power modes: Idle mode and Power-down
mode.
In Idle mode, execution of instructions is suspended until either a reset or interrupt occurs.
Peripheral functions continue operation during Idle mode and may generate interrupts to
cause the processor to resume execution. Idle mode eliminates power used by the
processor itself, memory systems and related controllers, and internal buses.
16/32-bit ARM microcontrollers with external memory interface
Rev. 02— 30 May 2005
DD
ramp (in the case of power on), the type of crystal
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
LPC2210/2220
28 of 49