EM78P152S datasheet(21/52 Pages) ETC1

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EM78P152/3S

8-Bit Microcontroller with OTP ROM

Product Specification (V1.8) 09.08.2009

• 17

(This specification is subject to change without further notice)

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)

3) Port 6 Input Status changed (if enabled)

The first two cases will cause the EM78P152/3S to reset. The T and P flags of R3 are

used to determine the source of the reset (wake-up). The last case is considered the

continuation of program execution and the global interrupt ("ENI" or "DISI" being

executed) determines whether or not the controller branches to the interrupt vector

following a wake-up. If ENI is executed before SLEP, the instruction will begin to

execute from Address 008H after wake-up. If DISI is executed before SLEP, the

operation will restart from the succeeding instruction right next to SLEP after a

wake-up.

Only one of Cases 2 and 3 can be enabled before going into the Sleep mode. That is,

[a] if Port 6 Input Status Change Interrupt is enabled before SLEP, WDT must be

disabled by software. However, the WDT bit in the option register remains

enabled. Hence, the EM78P152/3S can be awakened only by Case 1 or Case 3.

[b] if WDT is enabled before SLEP, Port 6 Input Status Change Interrupt must be

disabled. Hence, the EM78P152/3S can be awakened only by Case 1 or Case 2.

Refer to Section 5.6, Interrupt for further details.

If Port 6 Input Status Change Interrupt is used to wake-up the EM78P152/3S (Case [a]

above), the following instructions must be executed before SLEP:

MOV A, @xxxx1110b

; Select the WDT prescaler, it must be

; set over 1:1

CONTW

WDTC

; Clear WDT and prescaler

MOV A, @0xxxxxxxb

; Disable WDT

IOW RE

MOV R6, R6

; Read Port 6

MOV A, @00000x1xb

; Enable Port 6 input change interrupt

IOW RF

ENI (or DISI)

; Enable (or disable) global interrupt

SLEP

; Sleep

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