EM78P350N
8-Bit Microprocessor with OTP ROM
6.7 Reset and Wake-up
6.7.1 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)
A device is kept in a reset condition for the duration of approximately 18ms.2 after the
reset is detected. When in LXT mode, the reset time is 500ms. 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".
All I/O port pins are configured as input mode (high-impedance state).
The Watchdog Timer and prescaler are cleared.
When power is switched on, the upper 3 bits of R3 and upper 2 bits of R4 are
cleared.
The CONT register bits are set to all "0".
Executing the “SLEP” instruction will assert the sleep (power down) mode. While
entering sleep mode, the Oscillator, TCC, Timer 1, Timer 2, and Timer 3 are stopped.
The WDT (if enabled) is cleared but keeps on running.
The controller can be awakened by:
Case 1 External reset input on /RESET pin
Case 2 WDT time-out (if enabled)
Case 3 Port 6 input status changes (if ICWE is enabled)
Case 4 Comparator output status changes (if CMPWE is enabled)
Case 5 AD conversion completed (if ADWE enable)
Case 6 PWM/Timer overflows (if PWMWE enable)
The first two cases (1 & 2) will cause the EM78P350N to reset. The T and P flags of R3
can be used to determine the source of the reset (wake-up). Cases 3, 4, & 5 are
considered the continuation of program execution and the global interrupt ("ENI" or
"DISI" being executed) decides whether or not the controller branches to the interrupt
vector following wake-up. If ENI is executed before SLEP, the instruction will begin to
execute from address 0x8 after wake-up. If DISI is executed before SLEP, the
execution will restart from the instruction next to SLEP after wake-up. All sleep mode
wake up time is 2ms in high Crystal mode. In RC mode (IRC or ERC), wake-up time is
10µs. In low Crystal mode, wake-up time is 500ms.
2
VDD=5V, WDT Time-out period = 16.5ms ± 30%.
VDD=3V, WDT Time-out period = 18ms ± 30%.
50 •
Product Specification (V1.0) 09.14.2006
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
