Philips P89LPC908, P89LPC906, P89LPC907 user manual Comparator Configuration

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Philips Semiconductors	User’s Manual - Preliminary -

ANALOG COMPARATORS	P89LPC906/907/908
10. ANALOG COMPARATORS

An analog comparator is provided on the P89LPC906/907/908 . Comparator operation is such that the output is a logical one when the positive input is greater than the negative input (selectable from a pin or an internal reference voltage). Otherwise the output is a zero. The output may be read in a register. The output may also be routed to a pin. The comparator may be configured to cause an interrupt when the output value changes.

The connections to the comparator are shown in Figure 10-2. The comparator functions to VDD = 2.4V.

When the comparator is first enabled, the comparator output and interrupt flag are not guaranteed to be stable for 10 microseconds. The 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.

COMPARATOR CONFIGURATION

The comparator control register, CMP1, is shown in Figure 10-1. The possible configurations for the comparator are shown in Figure 10-3.

CMP1

Address: ACh

7

6

5

4

3

2

1

0

Not bit addressable

-

-

CE1

-

CN1

OE1

CO1

CMF1

Reset Source(s): Any reset

Reset Value: xx000000B

BIT

SYMBOL

FUNCTION

CMP.7, 6

-

Reserved for future use.

CMP.5

CE1

Comparator enable. When set, the comparator function is enabled. Comparator output is

stable 10 microseconds after CE1 is set.

CMP.4

-

Reserved for future use.

CMP.3

CN1

Comparator negative input select. When 0, the comparator reference pin CMPREF is

selected as the negative comparator input. When 1, the internal comparator reference,

Vref, is selected as the negative comparator input.

CMP.2

OE1

Output enable. When 1, the comparator output is connected to the CMP1 pin if the

comparator is enabled (CE1 = 1). This output is asynchronous to the CPU clock.

CMP.1

CO1

Comparator output, synchronized to the CPU clock to allow reading by software.

CMP.0

CMF1

Comparator interrupt flag. This bit is set by hardware whenever the comparator output

COn changes state. This bit will cause a hardware interrupt if enabled. Cleared by

software.

Figure 10-1: Comparator Control Register (CMP1)

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Contents User Manual Table of Contents Power-On reset code execution Brownout Detection Power-On Detection Power Reduction Modes103 List of Figures List of Figures P89LPC906 PIN ConfigurationsProduct Comparison Logic SymbolsKB Code Flash Block Diagram P89LPC906CPU Oscillator DividerUart Block Diagram P89LPC907Byte Data RAM ClockData RAM Port Block Diagram P89LPC908PIN Descriptions P89LPC906 P1.0 PIN Descriptions P89LPC907TxD P1.2Keyboard Input P1.0 P1.5 PIN Descriptions P89LPC908P1.1 RxDSpecial function registers table P89LPC906 Special function registersMSB LSB Hex Special function registers table P89LPC907 CMP1 Cmpref TRIM.5 TRIM.4 TRIM.3 TRIM.2 TRIM.1 TRIM.0 WDCON# Special function registers table P89LPC908 KB2 KB6 KB5 KB4 TL0 Data Memory OrganizationSFR CodeClock Definitions Enhanced CPUCPU Clock Oscclk LOW Speed Oscillator Option P89LPC906Clock Output P89LPC906 Oscillator Option SELECTION- P89LPC906ON-CHIP RC Oscillator Option Watchdog Oscillator OptionBIT Symbol Function CPU Clock Cclk Wakeup DelayExternal Clock Input Option P89LPC906 CPU Clock Cclk Modification Divm RegisterHigh freq LOW Power Select P89LPC906Med freq Low freqCPU Clocks Interrupt Priority Structure Flag Bits Address Enable Bits Priority RankingSummary of Interrupts P89LPC906 Description Interrupt ArbitrationExternal Interrupt PIN Glitch Suppression External Interrupt InputsSummary of Interrupts P89LPC907,P89LPC908 Description TI & RIBopd EBO Rtcf Kbif Interrupts QUASI-BIDIRECTIONAL Output Configuration Port ConfigurationsNumber of I/O Pins Available Clock Source Reset Option RSTPort latch data Open Drain Output ConfigurationPUSH-PULL Output Configuration INPUT-ONLY ConfigurationPort 0 Analog Functions Strong Port latch data Port pin Input data Glitch rejectionPort Output Configuration P89LPC907 Port Output Configuration P89LPC906Port Output Configuration P89LPC908 Ports Ports TMOD.7 TmodTMOD.6 TMOD.3Mode Overflows. ModeTamod P89LPC907 TAMOD.7-1Tcon T0C/T = Overflow TLn THn TFn Interrupt T0 Pin PclkT0C/T = Overflow THn TFnPclk TL0 Timer Overflow Toggle Output P89LPC907TR0 ENT0 Pclk TH0 Timers 0 REAL-TIME Clock Source UCFG1.2 UCFG1.1 UCFG1.0 Cclk Frequency RTC Clock Frequency FOSC2 FOSC1 FOSC0 RTCS10Xclk Divm CclkWDT Oscillator/DIVM RC Oscillator/DIVMUndefined External clock/DIVMChanging RTCS1-0 Reset Sources Affecting the REAL-TIME ClockREAL-TIME Clock INTERRUPT/WAKE UP Rtccon REAL-TIME CLOCK/SYSTEM Timer Brownout Detection Power Reduction Modes POWER-ON DetectionBrownout Options Power Reduction Modes Pcon Pcona Power Monitoring Functions Modes UartBaud Rate Generator and Selection SFR SpaceUpdating the BRGR1 and BRGR0 Sfrs SFR Locations for UARTsBreak Detect Framing ErrorBrgcon Scon Sstat More about Uart ModeSerial Port Mode 0 Double Buffering Must Be Disabled FE and RI when SM2 = 1 in Modes 2 Framing Error and RI in Modes 2 and 3 with SM2 =More about Uart Modes 2 PCON.6 RB8 SMOD0Double Buffering in Different Modes Double BufferingTransmission with and without Double Buffering 9TH BIT BIT 8 in Double Buffering Modes 1, 2Automatic Address Recognition Multiprocessor CommunicationsUart Uart Block Diagram of Reset POWER-ON Reset Code ExecutionRstsrc Comparator Configuration Internal Reference Voltage Comparator and Power Reduction ModesComparator Interrupt CIN1A CO1 CMP1 CmprefComparator Configuration Example Analog Comparators Kbcon KbpatnKbmask Watchdog Function Watchdog timer configurationWdte Wdse Function Feed Sequence Wdcon PRE2-PRE0 P89LPC906/907/908 Watchdog Timeout ValuesPrescaler Reset Pclk Watchdog Timer in Timer ModeWatchdog Control registerWatchdog Clock Source Power Down OperationPrescaler CLKWatchdog Timer Watchdog Timer Dual Data Pointers Software ResetAUXR1 Move code byte relative to Dptr to the accumulator MOVCA, @A+DPTRMOVXA, @DPTR MOVX@DPTR, aUsing Flash AS Data Storage FeaturesGeneral Description Introduction to IAP-LITEFlash Program Memory Fmcon Assembly language routine to erase/program all or part of a Accessing Additional Flash ElementsReading Additional Flash Elements ERASE-PROGRAMMING Additional Flash ElementsUCFG1 Fmadrl Conf UCFG1 User Configuration BytesP89LPC906 SECx User Security BytesAddress xxxxh Unprogrammed value 00hBootstat BootvecLogical ArithmeticData Transfer Mnemonic Description Bytes Cycles Hex CodeBranching BooleanB8-BF RetiD8-DF Miscellaneous2003 Dec Initial release 104 Index Dual Data Pointers Port 0 12, 13 SFR 109 P89LPC906/907/908