EM78P156E
Table 2 Usage of Port 6 input changed wake-up/interrupt function
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)
1
1. Disable WDT (using very carefully)
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
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").
VCC
ROC
Weekly
Pull-up
Q
P D
R
CLK
Q C
L
PCWR
PCRD
PORT
Q
Q
P D
R
CLK
C
L
IOD
PDWR
Rex *
0
1
M
U
X
PDRD
* 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).
* This specification is subject to be changed without notice.
B3-12
8.11.1999
EMC [ ELAN MICROELECTRONICS CORP ]
