B3-12

EM78P156E

Usage of Port 6 Input Status Changed Wake-up/Interrupt

(I) Wake-up from Port 6 input status changed

(II) Port 6 input status changed Interrupt

(a) Before SLEEP

1. Read I/O Port 6 (MOV R6,R6)

2. Execute "ENI"

2. Read I/O Port 6 (MOV R6,R6)

3. Enable interrupt (Set IOCF.1)

3. Execute "ENI" or "DISI"

4. If Port 6 changed (interrupt)

4. Enable interrupt (Set IOCF.1)

→ Interrupt vector (008H)

5. Execute “SLEP” instruction

(b) After wake-up

1. If "ENI"

→ Interrupt vector (008H)

2. If "DISI"

→ Next instruction

PCRD

PCWR

D

P

R

Q

Q

CLK

C

L

PDWR

PDRD

D

P

R

Q

Q

CLK

C

L

PORT

M

U

X

IOD

0

1

ROC

Rex *

Weekly

Pull-up

VCC

* The Rex is 430K ohm external resistor.

Fig. 8 The circuit of I/O port with R-option (P50,P51)

VI.5

RESET and Wake-up

1.

RESET

The RESET can be caused by

(1) Power-on reset

(2) /RESET pin input "low", or

(3) WDT time-out (if enabled).

Note that only power-on reset, or only voltage detector in Case (1) is enabled in the system by CODE option bit.

Refer to Fig. 9. The device will be kept in a RESET condition for a period of approx. 18ms (one-oscillator start-

up timer period) after the reset is detected. Once the RESET occurs, the following functions

are performed.

• The oscillator is running, or will be started.

• The Program Counter (R2) is set to all "0".

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

1

Note : Software disables WDT (watchdog timer) but hardware must be enabled before using port6 changed

wake-up function. (CODE Option Register, bit 11 (ENWDTB-) set to "1").

Table 2 Usage of Port 6 input changed wake-up/interrupt function