IBM EM78P447N Operational Registers, 1 R0 Indirect Addressing Register, 2 R1 Time Clock /Counter

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EM78P447N

8-Bit Microcontroller with OTP ROM

4.1 Operational Registers

4.1.1 R0 (Indirect Addressing Register)

R0 is not a physically implemented register. Its major function is to act as an indirect addressing pointer. Any instruction using R0 as a pointer actually accesses data pointed by the RAM Select Register (R4).

4.1.2 R1 (Time Clock /Counter)

Increased by an external signal edge, which is defined by TE bit (CONT-4) through the TCC pin, or by the instruction cycle clock.

Writable and readable as any other registers.

Defined by resetting PAB (CONT-3).

The prescaler is assigned to TCC, if the PAB bit (CONT-3) is reset.

The contents of the prescaler counter will be cleared only when TCC register is written a value.

4.1.3 R2 (Program Counter) & Stack

Depending on the device type, R2 and hardware stack are 10-bit wide. The structure is depicted in Fig.3.

Generating 1024⋅13 bits on-chip OTP ROM addresses to the relative programming instruction codes. One program page is 1024 words long.

R2 is set as all "0"s when under RESET condition.

"JMP" instruction allows direct loading of the lower 10 program counter bits. Thus, "JMP" allows PC to go to any location within a page.

"CALL" instruction loads the lower 10 bits of the PC, and then PC+1 is pushed into the stack. Thus, the subroutine entry address can be located anywhere within a page.

"RET" ("RETL k", "RETI") instruction loads the program counter with the contents of the top-level stack.

"ADD R2,A" allows the contents of ‘A’ to be added to the current PC, and the ninth and tenth bits of the PC are cleared.

"MOV R2,A" allows to load an address from the "A" register to the lower 8 bits of the PC, and the ninth and tenth bits of the PC are cleared.

Any instruction that writes to R2 (e.g. "ADD R2,A", "MOV R2,A", "BC R2,6",⋅⋅⋅⋅⋅) will cause the ninth and tenth bits (A8~A9) of the PC to be cleared. Thus, the computed jump is limited to the first 256 locations of a page.

Product Specification (V1.1) 03.30.2005

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(This specification is subject to change without further notice)

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Contents EM78P447N Elan Microelectronics Corporation Contents Specification Revision History General Description EM78P447NBWM PIN Assignment EM78P447NAS Pin Description Symbol Pin No Type FunctionEM78P447NAP and EM78P447NAM Pin Description EM78P447NCK and EN78P447NCM Pin Description Power supplyEM78P447NBP and EM78P447NBWM Pin Description EM78P447NDK and EM78P447NDM Pin Description Function Description3 R2 Program Counter & Stack Operational Registers1 R0 Indirect Addressing Register 2 R1 Time Clock /CounterFffh Call RET Retl RetiData Memory Configuration R5, R6 and R7 are I/O registers 5 R4 RAM Select Register6 R5~R7 Port 5 ~ Port7 7 R8~R1F and R20~R3E General Purpose RegisterControl Register Special Purpose Registers8 R3F Interrupt Status Register AccumulatorWDT Rate 3 IOC5 ~ IOC7 I/O Port Control RegisterIocb Wake-up Control Register for Port6 TCC RateWUE Ioce WDT Control RegisterExie Iocf Interrupt Mask RegisterTCC/WDT & Prescaler TCC and WDT Block DiagramIOD I/O PortsReset Reset and Wake-upSLEEP2 SLEEP1 Usage of Sleep1 and Sleep2 ModeSummary of the Initialized Values for Registers Address Name Reset Type BitIocb R3FISRExif Tcif WUE7 WUE6 WUE5 WUE4Events that may Affect the T and P Status Previous status before resetPrevious value before reset Status of RST, T, and P of Status RegisterInterrupt Controller Reset Block DiagramMode OscillatorOscillator Modes Fxt max.MHz Crystal Oscillator/Ceramic ResonatorsXTALSummary of Maximum Operating Speeds ConditionsLXT External RC Oscillator ModeOscillator Type Frequency Mode C1pF C2pF HXTCode Option Register Word Code Option RegisterProtect PR2~PR0 are protect bits, protect type as followingBit 12~0 Customer’s ID code Power On ConsiderationsExternal Power On Reset Circuit Customer ID Register WordResidue-Voltage Protection ResetInstruction Set Slep NOPDAA ContwRRC R Djza RDJZ R Rrca RAC Test Input/Output W aveform Timing DiagramItems Rating DC Electrical CharacteristicSymbol Parameter Condition Min Typ Max Unit Ta= 25 C, VDD= 5.0V±5%, VSS=Ta=- -40 C ~ 85 C, VDD=5V ±5%, VSS=0V AC Electrical CharacteristicSymbol Parameter Conditions Min Typ Max Unit Vih, Vil of TCC, /INT, /RESET Pin Device characteristicPort5, Port6 Port7 Voh vs. Ioh,VDD=5V Port5, Port6, and Port7 Voh vs. Ioh, VDD=3V Vol/Iol VDD=5V Vol/Iol VDD=3V Vol/Iol 100 Vol/Iol WDT Cext=100pF, Typical RC OSC Frequency Typical ICC1 and ICC2 vs. Temperature Maximum ICC1 and ICC2 vs. Temperature Typical ISB1 and ISB2 vs. Temperature Maximum ISB1 and ISB2 vs. Temperature EM78P447N HXT ImA Package Type Pin Count Package Size Lead plastic dual inline package（DIP）－ 300 milLead plastic dual inline package（DIP）－ 600 mil Lead plastic dual inline skinny package（DIP）－ 300 mil838 27TYP EM78P447N