Philips P89LPC907, P89LPC906, P89LPC908 user manual REAL-TIME Clock Source

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Philips Semiconductors	User’s Manual - Preliminary -

REAL-TIME CLOCK/SYSTEM TIMER	P89LPC906/907/908
6. REAL-TIME CLOCK/SYSTEM TIMER

The P89LPC906/907/908 has a simple Real-time clock/system timer that allows a user to continue running an accurate timer while the rest of the device is powered down. The Real-time clock can be an interrupt or a wake-up source (see Figure 6-2). The Real-time clock is a 23-bit down counter.

REAL-TIME CLOCK SOURCE

On the P89LPC906 the clock source for this counter can be either CCLK or the XTAL1-2 oscillator (XCLK) . On the P89LPC907 and P89LPC908 devicesthe clock source for this counter is CCLK. Please refer to Figure 2-3 "Block Diagram of Oscillator Control

-P89LPC906" in section "Clocks" on page 25. CCLK can have either the XTAL1-2 oscillator, the internal RC oscillator, or the Watchdog oscillator as its clock source. If the XTAL1-2 oscillator is used for producing CCLK, the RTC will use either the XTAL1- 2 oscillator’s output or CCLK as its clock source. The possible clocking combinations are shown in Table , below.

There are three SFRs used for the RTC:

•RTCCON - Real-time clock control.

•RTCH - Real-time clock counter reload high (bits 22-15).

•RTCL - Real-time clock counter reload low (bits 14-7).

The Real-time clock/system timer can be enabled by setting the RTCEN (RTCCON.0) bit. The Real-time clock is a 23-bit down counter (initialized to all 0’s when RTCEN = 0) that is comprised of a 7-bit prescaler and a 16-bit loadable down counter. When RTCEN is written with ’1’, the counter is first loaded with (RTCH,RTCL,’1111111’) and will count down. When it reaches all 0’s, the counter will be reloaded again with (RTCH,RTCL,’1111111’) and a flag - RTCF (RTCCON.7) - will be set.

Any write to RTCH and RTCL in-between the Real-time clock reloading will not cause reloading of the counter. When the current count terminates, the contents of RTCH and RTCL will be loaded into the counter and the new count will begin. An immediate reload of the counter can be forced by clearing the RTCEN bit to ’0’ and then setting it back to ’1’ .

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 P89LPC908 Port Output Configuration P89LPC906Port Output Configuration P89LPC907 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 = OverflowTR0 ENT0 Pclk TH0 Timer Overflow Toggle Output P89LPC907Pclk TL0 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 UndefinedREAL-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 Modes UartSFR Locations for UARTs SFR SpaceBaud Rate Generator and Selection Updating the BRGR1 and BRGR0 SfrsBrgcon Framing ErrorBreak Detect 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 Wdte Wdse Function Watchdog timer configurationWatchdog 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 AUXR1 Software ResetDual Data Pointers 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 ElementsUCFG1 ERASE-PROGRAMMING Additional Flash ElementsReading Additional Flash Elements Fmadrl Conf P89LPC906 User Configuration BytesUCFG1 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