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S3C80M4/F80M4
RESET
and POWER-DOWN
8-1
8
RESET and POWER-DOWN
SYSTEM RESET
OVERVIEW
During a power-on reset, the voltage at V
DD
goes to High level and the RESET pin is forced to Low level. The
RESET signal is input through a schmitt trigger circuit where it is then synchronized with the CPU clock. This
procedure brings the S3C80M4/F80M4 into a known operating status.
To allow time for internal CPU clock oscillation to stabilize, the RESET pin must be held to Low level for a
minimum time interval after the power supply comes within tolerance. The minimum required time of a reset
operation for oscillation stabilization is 1 millisecond.
Whenever a reset occurs during normal operation (that is, when both V
DD
and RESET are High level), the
nRESET pin is forced Low level and the reset operation starts. All system and peripheral control registers are
then reset to their default hardware values
In summary, the following sequence of events occurs during a reset operation:
— All interrupt is disabled.
— The watchdog function (basic timer) is enabled.
— Ports 0-1 and set to input mode, and all pull-up resistors are disabled for the I/O port.
— Peripheral control and data register settings are disabled and reset to their default hardware values.
— The program counter (PC) is loaded with the program reset address in the ROM, 0100H.
— When the programmed oscillation stabilization time interval has elapsed, the instruction stored in ROM
location 0100H (and 0101H) is fetched and executed at normal mode by smart option.
NORMAL MODE RESET OPERATION
A reset enables access to the S3C80M4 (4Kbyte) on-chip ROM. (The external interface is not automatically
configured).
NOTE
To program the duration of the oscillation stabilization interval, you make the appropriate settings to the
basic timer control register, BTCON,
before
entering Stop mode. Also, if you do not want to use the basic
timer watchdog function (which causes a system reset if a basic timer counter overflow occurs), you can
disable it by writing "1010B" to the upper nibble of BTCON.
Содержание S3C80M4/F80M4
Страница 1: ...S3C80M4 F80M4 8 BIT CMOS MICROCONTROLLERS USER S MANUAL Revision 1 ...
Страница 44: ...ADDRESS SPACES S3C80M4 F80M4 2 20 NOTES ...
Страница 84: ...CONTROL REGISTERS S3C80M4 F80M4 4 26 NOTES ...
Страница 102: ...INTERRUPT STRUCTURE S3C80M4 F80M4 5 18 NOTES ...
Страница 190: ...INSTRUCTION SET S3C80M4 F80M4 6 88 NOTES ...
Страница 202: ...RESET and POWER DOWN S3C80M4 F80M4 8 6 NOTES ...
Страница 216: ...8 BIT TIMER 0 S3C80M4 F80M4 11 4 NOTES ...
Страница 220: ...8 BIT PULSE WIDTH MODULATION S3C80M4 F80M4 12 4 NOTES ...
Страница 230: ...ELECTRICAL DATA S3C80M4 F80M4 13 10 NOTES ...
Страница 248: ...DEVELOPMENT TOOLS S3C80M4 F80M4 16 8 NOTES ...
Страница 249: ...This datasheet has been downloaded from www DatasheetCatalog com Datasheets for electronic components ...