LPC2292 datasheet(26/54 Pages) PHILIPS

26 / 54 page

LPC2292_2294_6

Product data sheet

Rev. 06 — 10 December 2007

26 of 54

NXP Semiconductors

LPC2292/LPC2294

16/32-bit ARM microcontrollers with external memory interface

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 VDD ramp (in the case of power-on), the type of crystal

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.

6.19.4 Code security (Code Read Protection - CRP)

This feature of the LPC2292/2294/01 allows the user to enable different levels of security

in the system so that access to the on-chip ﬂash and use of the JTAG and ISP can be

restricted. When needed, CRP is invoked by programming a speciﬁc pattern into a

dedicated ﬂash location. IAP commands are not affected by the CRP.

There are three levels of the Code Read Protection.

CRP1 disables access to chip via the JTAG and allows partial ﬂash update (excluding

ﬂash sector 0) using a limited set of the ISP commands. This mode is useful when CRP is

required and ﬂash ﬁeld updates are needed but all sectors can not be erased.

CRP2 disables access to chip via the JTAG and only allows full ﬂash erase and update

using a reduced set of the ISP commands.

Running an application with level CRP3 selected fully disables any access to chip via the

JTAG pins and the ISP. This mode effectively disables ISP override using P0[14] pin, too. It

is up to the user’s application to provide (if needed) ﬂash update mechanism using IAP

calls or call reinvoke ISP command to enable ﬂash update via UART0.

Remark: Devices without a /00 or /01 in the name have only a security level equivalent to

CRP2 available.

6.19.5 External interrupt inputs

The LPC2292/2294 include 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.

6.19.6 Memory mapping control

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 on-chip

ﬂash memory, or to the on-chip static RAM. This allows code running in different memory

spaces to have control of the interrupts.

CAUTION

If level three Code Read Protection (CRP3) is selected, no future factory testing can be

performed on the device.

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