LPC2157 datasheet(17/45 Pages) NXP

17 / 45 page

LPC2157_2158_2

Product data sheet

Rev. 02 — 9 February 2009

17 of 45

NXP Semiconductors

LPC2157/2158

Single-chip 16-bit/32-bit microcontrollers

FIQ has the highest priority. If more than one request is assigned to FIQ, the VIC

combines the requests to produce the FIQ signal to the ARM processor. The fastest

possible FIQ latency is achieved when only one request is classiﬁed as FIQ, because then

the FIQ service routine does not need to branch into the interrupt service routine but can

run from the interrupt vector location. If more than one request is assigned to the FIQ

class, the FIQ service routine will read a word from the VIC that identiﬁes which FIQ

source(s) is (are) requesting an interrupt.

Vectored IRQs have the middle priority. Sixteen of the interrupt requests can be assigned

to this category. Any of the interrupt requests can be assigned to any of the 16 vectored

IRQ slots, among which slot 0 has the highest priority and slot 15 has the lowest.

Non-vectored IRQs have the lowest priority.

The VIC combines the requests from all the vectored and non-vectored IRQs to produce

the IRQ signal to the ARM processor. The IRQ service routine can start by reading a

provides the address of the highest-priority requesting IRQs service routine, otherwise it

provides the address of a default routine that is shared by all the non-vectored IRQs. The

default routine can read another VIC register to see what IRQs are active.

6.5.1 Interrupt sources

Each peripheral device has one interrupt line connected to the Vectored Interrupt

Controller, but may have several internal interrupt ﬂags. Individual interrupt ﬂags may also

represent more than one interrupt source.

6.6 Pin connect block

The pin connect block allows selected pins of the microcontroller to have more than one

function. Conﬁguration registers control the multiplexers to allow connection between the

pin and the on chip peripherals. Peripherals should be connected to the appropriate pins

prior to being activated, and prior to any related interrupt(s) being enabled. Activity of any

enabled peripheral function that is not mapped to a related pin should be considered

undeﬁned.

The Pin Control Module with its pin select registers deﬁnes the functionality of the

microcontroller in a given hardware environment.

After reset all pins of Port 0 and Port 1 are conﬁgured as input with the following

exceptions: If debug is enabled, the JTAG pins will assume their JTAG functionality. The

pins associated with the I2C0 and I2C1 interface are open drain.

6.7 Fast general purpose parallel I/O

Device pins that are not connected to a speciﬁc peripheral function are controlled by the

GPIO registers. Pins may be dynamically conﬁgured as inputs or outputs. Separate

registers allow setting or clearing any number of outputs simultaneously. The value of the

output register may be read back, as well as the current state of the port pins.

LPC2157/2158 introduce accelerated GPIO functions over prior LPC2000 devices:

• GPIO registers are relocated to the ARM local bus for the fastest possible I/O timing.

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