IBM EM78P447N manual Reset and Wake-up

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EM78P447N

8-Bit Microcontroller with OTP ROM

4.5 RESET and Wake-up

4.5.1 RESET

A RESET is initiated by one of the following events-

(1)Power on reset, or

(2)/RESET pin input “low”, or

(3)WDT timeout. (if enabled)

The device is kept in a RESET condition for a period of approx. 18ms3 (one oscillator start-up timer period) after the reset is detected. Once the RESET occurs, the following functions are performed (refer to Fig.8).

The oscillator starts or is running

The Program Counter (R2) is set to all "1".

When power is switched on, bits 5~6 of R3 and the upper 2 bits of R4 are cleared.

All I/O port pins are configured as input mode (high-impedance state).

The Watchdog timer and prescaler are cleared.

Upon power on, the bits 5~6 of R3 are cleared.

Upon power on, the upper 2 bits of R4 are cleared.

The bits of CONT register are set to all "1" except bit 6 (INT flag).

IOCB register is set to ”1” (disable P60 ~ P67 wake-up function).

Bits 3 and 6 of IOCE register are cleared, and Bits 0, 4, and 5 are set to "1".

Bits 0 and 3 of R3F register and Bits 0 and 3 of IOCF registers are cleared.

The sleep (power down) mode is asserted by executing the “SLEP” instruction. While entering sleep mode, WDT (if enabled) is cleared but keeps on running. The controller can be awakened by-

(1)External reset input on /RESET pin;

(2)WDT time-out (if enabled)

The above two cases will cause the controller EM78P447N to reset. The T and P flags of R3 can be used to determine the source of the reset (wake-up).

In addition to the basic SLEEP1 MODE, EM78P447N has another sleep mode (designated as SLEEP2 MODE and is invoked by clearing the IOCE register “SLPC” bit). In the SLEEP2 MODE, the controller can be awakened by-

3NOTE: Vdd = 5V, set up time period = 16.2ms ± 30% Vdd = 3V, set up time period = 19.6ms ± 30%

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 Symbol Pin No Type Function EM78P447NAP and EM78P447NAM Pin DescriptionEM78P447NAS Pin Description Power supply EM78P447NBP and EM78P447NBWM Pin DescriptionEM78P447NCK and EN78P447NCM Pin Description EM78P447NDK and EM78P447NDM Pin Description Function Description1 R0 Indirect Addressing Register Operational Registers2 R1 Time Clock /Counter 3 R2 Program Counter & StackFffh Call RET Retl RetiData Memory Configuration 6 R5~R7 Port 5 ~ Port7 5 R4 RAM Select Register7 R8~R1F and R20~R3E General Purpose Register R5, R6 and R7 are I/O registers8 R3F Interrupt Status Register Special Purpose RegistersAccumulator Control RegisterIocb Wake-up Control Register for Port6 3 IOC5 ~ IOC7 I/O Port Control RegisterTCC Rate WDT 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 BitExif Tcif R3FISRWUE7 WUE6 WUE5 WUE4 IocbPrevious value before reset Previous status before resetStatus of RST, T, and P of Status Register Events that may Affect the T and P StatusInterrupt Controller Reset Block DiagramOscillator Oscillator ModesMode Summary of Maximum Operating Speeds Crystal Oscillator/Ceramic ResonatorsXTALConditions Fxt max.MHzOscillator Type Frequency Mode C1pF C2pF External RC Oscillator ModeHXT LXTCode Option Register Word Code Option RegisterProtect PR2~PR0 are protect bits, protect type as followingExternal Power On Reset Circuit Power On ConsiderationsCustomer ID Register Word Bit 12~0 Customer’s ID codeResidue-Voltage Protection ResetInstruction Set DAA NOPContw SlepDJZ R Djza RRrca R RRC RAC Test Input/Output W aveform Timing DiagramSymbol Parameter Condition Min Typ Max Unit DC Electrical CharacteristicTa= 25 C, VDD= 5.0V±5%, VSS= Items RatingAC Electrical Characteristic Symbol Parameter Conditions Min Typ Max UnitTa=- -40 C ~ 85 C, VDD=5V ±5%, VSS=0V 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