em78p156n ELAN Microelectronics Corp, em78p156n Datasheet - Page 20

• Manufacturer Part Number: em78p156n
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

The device is kept in a RESET condition for a period of approx. 18ms
after the reset is detected. Once the RESET occurs, the following functions are performed. Refer to Fig.9.
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-
The first two cases will cause the EM78P156N to reset. The T and P flags of R3 can be 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) decides whether or not the controller branches to the interrupt
This specification is subject to change without prior notice.
4.5 RESET and Wake-up
1. RESET
1
NOTE: Vdd = 5V, set up time period = 16.8ms ± 30%
A RESET is initiated by one of the following events-
(1) Power on reset.
(2) /RESET pin input "low", or
(3) WDT time-out (if enabled).
• 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).
• The Watchdog timer and prescaler are cleared.
• When power is switched on, the upper 3 bits of R3 are cleared.
• The bits of the CONT register are set to all "1" except for the Bit 6 (INT flag).
• The bits of the IOCA register are set to all "1".
• The bits of the IOCB register are set to all "1".
• The IOCC register is cleared.
• The bits of the IOCD register are set to all "1".
• Bit 7 of the IOCE register is set to "1", and Bits 4 and 6 are cleared.
• Bits 0~2 of RF and bits 0~2 of IOCF register are cleared.
(1) External reset input on /RESET pin,
(2) WDT time-out (if enabled), or
(3) Port 6 input status changes (if enabled).
Vdd = 3V, set up time period = 18ms ± 30%
20
1
(one oscillator start-up timer period)
EM78P156N
OTP ROM
07.29.2004 (V1.2)