IBM EM78P259N/260N 6.5 Reset and Wake-up

EM78P259N/260N
8-Bit Microprocessor with OTP ROM
Product Specification (V1.2) 05.18.2007 • 31
(This specification is subject to change without further notice)
6.4.1 Usage of Port 5 Input Change Wake-up/Interrupt Function
(1) Wake-up (2) Wake-up and Interrupt
(a) Before Sleep (a) Before Sleep
1. Disable WDT 1. Disable WDT
2. Read I/O Port 5 (MOV R5,R5) 2. Read I/O Port 5 (MOV R5,R5)
3. Execute "ENI" or "DISI" 3. Execute "ENI" or "DISI"
4. Enable wake-up bit (Set RE ICWE =1) 4. Enable wake-up bit (Set RE ICWE =1)
5. Execute "SLEP" instruction 5. Enable interrupt (Set IOCF0 ICIE =1)
(b) After wake-up 6. Execute "SLEP" instruction
→ Next instruction (b) After wake-up
1. IF "ENI" → Interrupt vector (006H)
2. IF "DISI" → Next instruction
(3) Interrupt
(a) Before Port 5 pin change
1. Read I/O Port 5 (MOV R5,R5)
2. Execute "ENI" or "DISI"
3. Enable interrupt (Set IOCF0 ICIE =1)
(b) After Port 5 pin changed (interrupt)
1. IF "ENI" → Interrupt vector (006H)
2. IF "DISI" → Next instruction
6.5 Reset and Wake-up
6.5.1 Reset and Wake-up Operation
A reset is initiated by one of the following events:
1. Power-on reset
2. /RESET pin input "low"
3. WDT time-out (if enabled).
The device is kept under reset condition f or a period of approximately 18ms3 (except in
LXT mode) after the reset is detected. When in LXT mode, the reset time is 500ms.
Two choices (18ms3 or 4.5ms4) are available for WDT-time out period. Once a reset
occurs, the following functions are performed (the initial Address is 000h):
 The oscillator continues running, or will be started (if in sleep mode)
 The Program Counter (R2) is set to all "0"
3 VDD=5V, WDT Time-out period = 16.5ms ± 30%.
VDD=3V, WDT Time-out period = 18ms ± 30%.
4 VDD=5V, WDT Time-out period = 4.2ms ± 30%.
VDD=3V, WDT Time-out period = 4.5ms ± 30%.