Philips P89LPC907, P89LPC908 Oscillator Option SELECTION- P89LPC906, Clock Output P89LPC906

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Philips Semiconductors

User’s Manual - Preliminary -

 

 

 

CLOCKS

P89LPC906/907/908

 

Quartz crystal or ceramic resonator

The oscillator must be configured in one of the following modes:

-Low Frequency Crystal

-Medium Frequency Crystal

-High Frequency Crystal

*A series resistor may be required to limit crystal drive levels. This is especially

important for low frequency crystals.

 

P89LPC906

 

XTAL1

*

XTAL2

 

Figure 2-1: Using the Crystal Oscillator - P89LPC906

OSCILLATOR OPTION SELECTION- P89LPC906

The oscillator option is selectable either by the FOSC2:0 bits in UCFG1 or by the RTCS1:0 bits in RTCCON. If the FOSC2:0 bits select an OSCCLK source of either the internal RC oscillator or the WDT oscillator, then the RTCS1:0 bits will select the oscillator option for the crystal oscillator. Otherwise, the crystal oscillator option is selected by FOSC2:0. See Table 6-1 and Table 6-2.

CLOCK OUTPUT - P89LPC906

The P89LPC906 supports a user selectable clock output function on the XTAL2 / CLKOUT pin when no crystal oscillator is being used. This condition occurs if another clock source has been selected (on-chip RC oscillator, watchdog oscillator, external clock input on X1) and if the Real-Time clock is not using the crystal oscillator as its clock source. This allows external devices to synchronize to the P89LPC906. This output is enabled by the ENCLK bit in the TRIM register

The frequency of this clock output is 1/2 that of the CCLK. If the clock output is not needed in Idle mode, it may be turned off prior to entering Idle, saving additional power. Note: on reset, the TRIM SFR is initialized with a factory preprogrammed value. Therefore when setting or clearing the ENCLK bit, the user should retain the contents of bits 5:0 of the TRIM register. This can be done by reading the contents of the TRIM register (into the ACC for example), modifying bit 6, and writing this result back into the TRIM register. Alternatively, the "ANL direct" or "ORL direct" instructions can be used to clear or set bit 6 of the TRIM register.Increasing the TRIM value will decrease the oscillator frequency.

ON-CHIP RC OSCILLATOR OPTION

The P89LPC906/907/908 has a 6-bit field within the TRIM register that can be used to tune the frequency of the RC oscillator. During reset, the TRIM value is initialized to a factory pre-programmed value to adjust the oscillator frequency to 7.373 MHz, ±1%. (Note: the initial value is better than 1%; please refer to the datasheet for behavior over temperature). End user applications can write to the TRIM register to adjust the on-chip RC oscillator to other frequencies. Increasing the TRIM value will decrease the oscillator frequency.

If CCLK is 8MH or slower, the CLKLP SFR bit (AUXR1.7) can be set to ’1’ to reduce power consumption. On reset, CLKLP is ’0’ allowing highest performance access. This bit can then be set in software if CCLK is running at 8MHz or slower

WATCHDOG OSCILLATOR OPTION

The watchdog has a separate oscillator which has a nominal frequency of 400KHz. This oscillator can be used to save power when a high clock frequency is not needed.

2003 Dec 8

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Contents User Manual Table of Contents Brownout Detection Power-On Detection Power Reduction Modes Power-On reset code execution103 List of Figures List of Figures PIN Configurations P89LPC906Logic Symbols Product ComparisonCPU Block Diagram P89LPC906KB Code Flash Oscillator DividerByte Data RAM Block Diagram P89LPC907Uart ClockBlock Diagram P89LPC908 Data RAM PortPIN Descriptions P89LPC906 TxD PIN Descriptions P89LPC907P1.0 P1.2P1.1 PIN Descriptions P89LPC908Keyboard Input P1.0 P1.5 RxDSpecial function registers Special function registers table P89LPC906MSB 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 SFR Memory OrganizationData CodeCPU Clock Oscclk Enhanced CPUClock Definitions LOW Speed Oscillator Option P89LPC906ON-CHIP RC Oscillator Option Oscillator Option SELECTION- P89LPC906Clock Output P89LPC906 Watchdog Oscillator OptionExternal Clock Input Option P89LPC906 CPU Clock Cclk Wakeup DelayBIT Symbol Function CPU Clock Cclk Modification Divm RegisterMed freq LOW Power Select P89LPC906High freq Low freqCPU Clocks Summary of Interrupts P89LPC906 Description Flag Bits Address Enable Bits Priority RankingInterrupt Priority Structure Interrupt ArbitrationSummary of Interrupts P89LPC907,P89LPC908 Description External Interrupt InputsExternal Interrupt PIN Glitch Suppression TI & RIBopd EBO Rtcf Kbif Interrupts Number of I/O Pins Available Clock Source Reset Option Port ConfigurationsQUASI-BIDIRECTIONAL Output Configuration RSTOpen Drain Output Configuration Port latch dataPort 0 Analog Functions INPUT-ONLY ConfigurationPUSH-PULL Output Configuration Strong Port latch data Port pin Input data Glitch rejectionPort Output Configuration P89LPC908 Port Output Configuration P89LPC906Port Output Configuration P89LPC907 Ports Ports TMOD.6 TmodTMOD.7 TMOD.3Tamod P89LPC907 Overflows. ModeMode TAMOD.7-1Tcon T0C/T = Overflow PclkT0C/T = Overflow TLn THn TFn Interrupt T0 Pin THn TFnTR0 ENT0 Pclk TH0 Timer Overflow Toggle Output P89LPC907Pclk TL0 Timers 0 REAL-TIME Clock Source Xclk FOSC2 FOSC1 FOSC0 RTCS10UCFG1.2 UCFG1.1 UCFG1.0 Cclk Frequency RTC Clock Frequency Divm CclkUndefined RC Oscillator/DIVMWDT Oscillator/DIVM External clock/DIVMREAL-TIME Clock INTERRUPT/WAKE UP Reset Sources Affecting the REAL-TIME ClockChanging RTCS1-0 Rtccon REAL-TIME CLOCK/SYSTEM Timer Brownout Detection Brownout Options POWER-ON DetectionPower Reduction Modes Power Reduction Modes Pcon Pcona Power Monitoring Functions Uart ModesUpdating the BRGR1 and BRGR0 Sfrs SFR SpaceBaud Rate Generator and Selection SFR Locations for UARTsBrgcon Framing ErrorBreak Detect Scon More about Uart Mode SstatSerial Port Mode 0 Double Buffering Must Be Disabled More about Uart Modes 2 Framing Error and RI in Modes 2 and 3 with SM2 =FE and RI when SM2 = 1 in Modes 2 PCON.6 RB8 SMOD0Double Buffering Double Buffering in Different Modes9TH BIT BIT 8 in Double Buffering Modes 1, 2 Transmission with and without Double BufferingMultiprocessor Communications Automatic Address RecognitionUart Uart POWER-ON Reset Code Execution Block Diagram of ResetRstsrc Comparator Configuration Comparator Interrupt Comparator and Power Reduction ModesInternal Reference Voltage CIN1A CO1 CMP1 CmprefComparator Configuration Example Analog Comparators Kbpatn KbconKbmask Wdte Wdse Function Watchdog timer configurationWatchdog Function Feed Sequence Wdcon P89LPC906/907/908 Watchdog Timeout Values PRE2-PRE0Watchdog Watchdog Timer in Timer ModePrescaler Reset Pclk Control registerPrescaler Power Down OperationWatchdog Clock Source CLKWatchdog Timer Watchdog Timer AUXR1 Software ResetDual Data Pointers MOVXA, @DPTR MOVCA, @A+DPTRMove code byte relative to Dptr to the accumulator MOVX@DPTR, aGeneral Description FeaturesUsing Flash AS Data Storage Introduction to IAP-LITEFlash Program Memory Fmcon Accessing Additional Flash Elements Assembly language routine to erase/program all or part of aUCFG1 ERASE-PROGRAMMING Additional Flash ElementsReading Additional Flash Elements Fmadrl Conf P89LPC906 User Configuration BytesUCFG1 Address xxxxh User Security BytesSECx Unprogrammed value 00hBootvec BootstatArithmetic LogicalMnemonic Description Bytes Cycles Hex Code Data TransferBoolean BranchingD8-DF RetiB8-BF Miscellaneous2003 Dec Initial release 104 Index Dual Data Pointers Port 0 12, 13 SFR 109 P89LPC906/907/908
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