P89LPC932A1FDH View Datasheet(PDF) - NXP Semiconductors.

Part Name

Description

Manufacturer

P89LPC932A1FDH

8-bit microcontroller with accelerated two-clock 80C51 core 8 kB 3 V byte-erasable flash with 512-byte data EEPROM

NXP Semiconductors. 

NXP Semiconductors

P89LPC932A1

8-bit microcontroller with accelerated two-clock 80C51 core

7.23 Analog comparators

Two analog comparators are provided on the P89LPC932A1. Input and output options

allow use of the comparators in a number of different configurations. Comparator

operation is such that the output is a logic 1 (which may be read in a register and/or routed

to a pin) when the positive input (one of two selectable pins) is greater than the negative

input (selectable from a pin or an internal reference voltage). Otherwise the output is a

zero. Each comparator may be configured to cause an interrupt when the output value

changes.

The overall connections to both comparators are shown in Figure 20. The comparators

function to VDD = 2.4 V.

When each comparator is first enabled, the comparator output and interrupt flag are not

guaranteed to be stable for 10 microseconds. The corresponding comparator interrupt

should not be enabled during that time, and the comparator interrupt flag must be cleared

before the interrupt is enabled in order to prevent an immediate interrupt service.

(P0.4) CIN1A

(P0.3) CIN1B

(P0.5) CMPREF

Vref(bg)

CP1

comparator 1

CO1

OE1

CN1

change detect

CMF1

CMP1 (P0.6)

(P0.2) CIN2A

(P0.1) CIN2B

CP2

comparator 2

change detect

CMF2

CN2

CO2

OE2

Fig 20. Comparator input and output connections

EC

CMP2 (P0.0)

002aaa904

interrupt

7.23.1 Internal reference voltage

An internal reference voltage generator may supply a default reference when a single

comparator input pin is used. The value of the internal reference voltage, referred to as

VREF, is 1.23 V ± 10 %.

7.23.2 Comparator interrupt

Each comparator has an interrupt flag contained in its configuration register. This flag is

set whenever the comparator output changes state. The flag may be polled by software or

may be used to generate an interrupt. The two comparators use one common interrupt

vector. If both comparators enable interrupts, after entering the interrupt service routine,

the user needs to read the flags to determine which comparator caused the interrupt.

P89LPC932A1_3

Product data sheet

Rev. 03 — 12 March 2007

© NXP B.V. 2007. All rights reserved.

38 of 64

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