Philips P89LPC906, P89LPC908, P89LPC907 user manual Comparator Configuration Example

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Philips Semiconductors	User’s Manual - Preliminary -

ANALOG COMPARATORS	P89LPC906/907/908

If the comparator output to a pin is enabled, the pin should be configured in the push-pull mode in order to obtain fast switching times while in power down mode. The reason is that with the oscillator stopped, the temporary strong pullup that normally occurs during switching on a quasi-bidirectional port pin does not take place.

The comparator consumes power in Power down and Idle modes, as well as in the normal operating mode. This fact should be taken into account when system power consumption is an issue. To minimize power consumption, the user can disable the comparator via PCONA.5 or put the device in Total Power down mode.

COMPARATOR CONFIGURATION EXAMPLE

The code shown below is an example of initializing the comparator. This comparator is configured to use the CMPREF inputs. The comparator output drives the CMP pin and generates an interrupt when the comparator output changes.

CMPINIT:
MOV	PT0AD,#030h	; Disable digital INPUTS on pins that are used
		; for analog functions: CIN, CMPREF.
ANL	P0M2,#0CFh	; Disable digital OUTPUTS on pins that are used
ORL	P0M1,#030h	; for analog functions: CIN, CMPREF.
MOV	CMP1,#024h	; Turn on comparator and set up for:
		; - Negative input from CMPREF pin.
		; - Output to CMP pin enabled.
CALL	delay10us	; The comparator has to start up for at
		; least 10 microseconds before use.
ANL	CMP1,#0FEh	; Clear comparator interrupt flag.
SETB	EC	; Enable the comparator interrupt. The
		; priority is left at the current value.
SETB	EA	; Enable the interrupt system (if needed).
RET		; Return to caller.

The interrupt routine used for the comparator must clear the interrupt flag (CMF1 in this case) before returning.

2003 Dec 8

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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 SymbolsOscillator Divider Block Diagram P89LPC906KB Code Flash CPUClock Block Diagram P89LPC907Uart Byte Data RAMData RAM Port Block Diagram P89LPC908PIN Descriptions P89LPC906 P1.2 PIN Descriptions P89LPC907P1.0 TxDRxD PIN Descriptions P89LPC908Keyboard Input P1.0 P1.5 P1.1Special 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 Code Memory OrganizationData SFRLOW Speed Oscillator Option P89LPC906 Enhanced CPUClock Definitions CPU Clock OscclkWatchdog Oscillator Option Oscillator Option SELECTION- P89LPC906Clock Output P89LPC906 ON-CHIP RC Oscillator OptionCPU Clock Cclk Modification Divm Register CPU Clock Cclk Wakeup DelayBIT Symbol Function External Clock Input Option P89LPC906Low freq LOW Power Select P89LPC906High freq Med freqCPU Clocks Interrupt Arbitration Flag Bits Address Enable Bits Priority RankingInterrupt Priority Structure Summary of Interrupts P89LPC906 DescriptionTI & RI External Interrupt InputsExternal Interrupt PIN Glitch Suppression Summary of Interrupts P89LPC907,P89LPC908 DescriptionBopd EBO Rtcf Kbif Interrupts RST Port ConfigurationsQUASI-BIDIRECTIONAL Output Configuration Number of I/O Pins Available Clock Source Reset OptionPort latch data Open Drain Output ConfigurationStrong Port latch data Port pin Input data Glitch rejection INPUT-ONLY ConfigurationPUSH-PULL Output Configuration Port 0 Analog FunctionsPort Output Configuration P89LPC906 Port Output Configuration P89LPC907Port Output Configuration P89LPC908 Ports Ports TMOD.3 TmodTMOD.7 TMOD.6TAMOD.7-1 Overflows. ModeMode Tamod P89LPC907Tcon THn TFn PclkT0C/T = Overflow TLn THn TFn Interrupt T0 Pin T0C/T = OverflowTimer Overflow Toggle Output P89LPC907 Pclk TL0TR0 ENT0 Pclk TH0 Timers 0 REAL-TIME Clock Source Divm Cclk FOSC2 FOSC1 FOSC0 RTCS10UCFG1.2 UCFG1.1 UCFG1.0 Cclk Frequency RTC Clock Frequency XclkExternal clock/DIVM RC Oscillator/DIVMWDT Oscillator/DIVM UndefinedReset Sources Affecting the REAL-TIME Clock Changing RTCS1-0REAL-TIME Clock INTERRUPT/WAKE UP Rtccon REAL-TIME CLOCK/SYSTEM Timer Brownout Detection POWER-ON Detection Power Reduction ModesBrownout Options Power Reduction Modes Pcon Pcona Power Monitoring Functions Modes UartSFR Locations for UARTs SFR SpaceBaud Rate Generator and Selection Updating the BRGR1 and BRGR0 SfrsFraming Error Break DetectBrgcon Scon Sstat More about Uart ModeSerial Port Mode 0 Double Buffering Must Be Disabled PCON.6 RB8 SMOD0 Framing Error and RI in Modes 2 and 3 with SM2 =FE and RI when SM2 = 1 in Modes 2 More about Uart Modes 2Double 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 CIN1A CO1 CMP1 Cmpref Comparator and Power Reduction ModesInternal Reference Voltage Comparator InterruptComparator Configuration Example Analog Comparators Kbcon KbpatnKbmask Watchdog timer configuration Watchdog FunctionWdte Wdse Function Feed Sequence Wdcon PRE2-PRE0 P89LPC906/907/908 Watchdog Timeout ValuesControl register Watchdog Timer in Timer ModePrescaler Reset Pclk WatchdogCLK Power Down OperationWatchdog Clock Source PrescalerWatchdog Timer Watchdog Timer Software Reset Dual Data PointersAUXR1 MOVX@DPTR, a MOVCA, @A+DPTRMove code byte relative to Dptr to the accumulator MOVXA, @DPTRIntroduction to IAP-LITE FeaturesUsing Flash AS Data Storage General DescriptionFlash Program Memory Fmcon Assembly language routine to erase/program all or part of a Accessing Additional Flash ElementsERASE-PROGRAMMING Additional Flash Elements Reading Additional Flash ElementsUCFG1 Fmadrl Conf User Configuration Bytes UCFG1P89LPC906 Unprogrammed value 00h User Security BytesSECx Address xxxxhBootstat BootvecLogical ArithmeticData Transfer Mnemonic Description Bytes Cycles Hex CodeBranching BooleanMiscellaneous RetiB8-BF D8-DF2003 Dec Initial release 104 Index Dual Data Pointers Port 0 12, 13 SFR 109 P89LPC906/907/908