Philips P89LPC907, P89LPC906 Multiprocessor Communications, Automatic Address Recognition

Page 68

Philips Semiconductors

User’s Manual - Preliminary -

 

 

 

UART

P89LPC906/907/908

 

-If DBISEL is ’1’ and INTLO is ’1’, a Tx interrupt will occur at the end of the STOP bit of the data currently in the shifter (which is also the last data).

7.If there is more data, the CPU writes to TB8 again.

8.The CPU writes to SBUF again. Then:

-If INTLO is ’0’, the new data will be loaded and a Tx interrupt will occur at the beginning of the STOP bit of the data currently in the shifter.

-If INTLO is ’1’, the new data will be loaded and a Tx interrupt will occur at the end of the STOP bit of the data currently in the shifter.

Go to 4.

Note that if DBISEL is ’1’ and the CPU is writing to SBUF when the STOP bit of the last data is shifted out, there can be an uncertainty of whether a Tx interrupt is generated already with the UART not knowing whether there is any more data following.

MULTIPROCESSOR COMMUNICATIONS

UART modes 2 and 3 have a special provision for multiprocessor communications. In these modes, 9 data bits are received or transmitted. When data is received, the 9th bit is stored in RB8. The UART can be programmed such that when the stop bit is received, the serial port interrupt will be activated only if RB8 = 1. This feature is enabled by setting bit SM2 in SCON. One way to use this feature in multiprocessor systems is as follows:

When the master processor wants to transmit a block of data to one of several slaves, it first sends out an address byte which identifies the target slave. An address byte differs from a data byte in that the 9th bit is 1 in an address byte and 0 in a data byte. With SM2 = 1, no slave will be interrupted by a data byte. An address byte, however, will interrupt all slaves, so that each slave can examine the received byte and see if it is being addressed. The addressed slave will clear its SM2 bit and prepare to receive the data bytes that follow. The slaves that weren’t being addressed leave their SM2 bits set and go on about their business, ignoring the subsequent data bytes.

Note that SM2 has no effect in Mode 0, and must be ’0’ in Mode 1.

AUTOMATIC ADDRESS RECOGNITION

Automatic Address Recognition is a feature which allows the UART to recognize certain addresses in the serial bit stream by using hardware to make the comparisons. This feature saves a great deal of software overhead by eliminating the need for the software to examine every serial address which passes by the serial port. This feature is enabled by setting the SM2 bit in SCON. In the 9 bit UART modes (mode 2 and mode 3), the Receive Interrupt flag (RI) will be automatically set when the received byte contains either the “Given” address or the “Broadcast” address. The 9 bit mode requires that the 9th information bit is a 1 to indicate that the received information is an address and not data.

Using the Automatic Address Recognition feature allows a master to selectively communicate with one or more slaves by invoking the Given slave address or addresses. All of the slaves may be contacted by using the Broadcast address. Two special Function Registers are used to define the slave’s address, SADDR, and the address mask, SADEN. SADEN is used to define which bits in the SADDR are to be used and which bits are “don’t care”. The SADEN mask can be logically ANDed with the SADDR to create the “Given” address which the master will use for addressing each of the slaves. Use of the Given address allows multiple slaves to be recognized while excluding others. The following examples will help to show the versatility of this scheme:

Slave 0

SADDR = 1100

0000

 

SADEN = 1111

1101

 

Given

= 1100

00X0

Slave 1

SADDR = 1100

0000

 

SADEN = 1111

1110

 

Given

= 1100

000X

In the above example SADDR is the same and the SADEN data is used to differentiate between the two slaves. Slave 0 requires a 0 in bit 0 and it ignores bit 1. Slave 1 requires a 0 in bit 1 and bit 0 is ignored. A unique address for Slave 0 would be 1100 0010

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 ComparisonBlock Diagram P89LPC906 KB Code FlashCPU Oscillator DividerBlock Diagram P89LPC907 UartByte Data RAM ClockBlock Diagram P89LPC908 Data RAM PortPIN Descriptions P89LPC906 PIN Descriptions P89LPC907 P1.0TxD P1.2PIN Descriptions P89LPC908 Keyboard Input P1.0 P1.5P1.1 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 Memory Organization DataSFR CodeEnhanced CPU Clock DefinitionsCPU Clock Oscclk LOW Speed Oscillator Option P89LPC906Oscillator Option SELECTION- P89LPC906 Clock Output P89LPC906ON-CHIP RC Oscillator Option Watchdog Oscillator OptionCPU Clock Cclk Wakeup Delay BIT Symbol FunctionExternal Clock Input Option P89LPC906 CPU Clock Cclk Modification Divm RegisterLOW Power Select P89LPC906 High freqMed freq Low freqCPU Clocks Flag Bits Address Enable Bits Priority Ranking Interrupt Priority StructureSummary of Interrupts P89LPC906 Description Interrupt ArbitrationExternal Interrupt Inputs External Interrupt PIN Glitch SuppressionSummary of Interrupts P89LPC907,P89LPC908 Description TI & RIBopd EBO Rtcf Kbif Interrupts Port Configurations QUASI-BIDIRECTIONAL Output ConfigurationNumber of I/O Pins Available Clock Source Reset Option RSTOpen Drain Output Configuration Port latch dataINPUT-ONLY Configuration PUSH-PULL Output ConfigurationPort 0 Analog Functions Strong Port latch data Port pin Input data Glitch rejectionPort Output Configuration P89LPC908 Port Output Configuration P89LPC906Port Output Configuration P89LPC907 Ports Ports Tmod TMOD.7TMOD.6 TMOD.3Overflows. Mode ModeTamod P89LPC907 TAMOD.7-1Tcon Pclk T0C/T = Overflow TLn THn TFn Interrupt T0 PinT0C/T = Overflow THn TFnTR0 ENT0 Pclk TH0 Timer Overflow Toggle Output P89LPC907Pclk TL0 Timers 0 REAL-TIME Clock Source FOSC2 FOSC1 FOSC0 RTCS10 UCFG1.2 UCFG1.1 UCFG1.0 Cclk Frequency RTC Clock FrequencyXclk Divm CclkRC Oscillator/DIVM WDT Oscillator/DIVMUndefined 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 ModesSFR Space Baud Rate Generator and SelectionUpdating the BRGR1 and BRGR0 Sfrs SFR Locations for UARTsBrgcon Framing ErrorBreak Detect Scon More about Uart Mode SstatSerial Port Mode 0 Double Buffering Must Be Disabled Framing Error and RI in Modes 2 and 3 with SM2 = FE and RI when SM2 = 1 in Modes 2More about Uart 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 and Power Reduction Modes Internal Reference VoltageComparator Interrupt 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 Timer in Timer Mode Prescaler Reset PclkWatchdog Control registerPower Down Operation Watchdog Clock SourcePrescaler CLKWatchdog Timer Watchdog Timer AUXR1 Software ResetDual Data Pointers MOVCA, @A+DPTR Move code byte relative to Dptr to the accumulatorMOVXA, @DPTR MOVX@DPTR, aFeatures Using Flash AS Data StorageGeneral Description 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 User Security Bytes SECxAddress xxxxh Unprogrammed value 00hBootvec BootstatArithmetic LogicalMnemonic Description Bytes Cycles Hex Code Data TransferBoolean BranchingReti B8-BFD8-DF Miscellaneous2003 Dec Initial release 104 Index Dual Data Pointers Port 0 12, 13 SFR 109 P89LPC906/907/908
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