STC12LE5616AD datasheet(47/377 Pages) STC

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2.3 RESET Sources

In STC12C5620AD, there are 5 sources to generate internal reset. They are RST pin reset, software reset, On-

chip power-on-reset(if delay 200mS after power-on reset, the reset mode is On-chip MAX810 POR timing delay

which actully add 200mS delay after power-on reset), internal low-voltage detection reset and Watch-Dog-Timer

reset.

2.3.1 RESET Pin

External RST pin reset accomplishes the MCU reset by forcing a reset pulse to RST pin from external.

Asserting an active-high signal and keeping at least 24 cycles plus 10us on the RST pin generates a

reset. If the signal on RST pin changed active-low level, MCU will end the reset state and start to run

from the 0000H of user procedures.

2.3.2 Software RESET

Writing an “1” to SWRST bit in ISP_CONTR register will generate a internal reset.

ISP_CONTR: ISP/IAP Control Register

SFR Name

SFR Address

bit

ISP_CONTR

E7H

name ISPEN

SWBS SWRST CMD_FAIL

WT2

WT1

WT0

ISPEN : ISP/IAP operation enable.

0 : Global disable all ISP/IAP program/erase/read function.

1 : Enable ISP/IAP program/erase/read function.

SWBS: software boot selection control bit

0 : Boot from main-memory after reset.

1 : Boot from ISP memory after reset.

SWRST: software reset trigger control.

0 : No operation

1 : Generate software system reset. It will be cleared by hardware automatically.

CMD_FAIL: Command Fail indication for ISP/IAP operation.

0 : The last ISP/IAP command has finished successfully.

1 : The last ISP/IAP command fails. It could be caused since the access of flash memory was inhibited.

;Software reset from user appliction program area (AP area) and switch to AP area to run program

MOV ISP_CONTR, #00100000B ;SWBS = 0(Select AP area), SWRST = 1(Software reset)

;Software reset from system ISP monitor program area (ISP area) and switch to AP area to run program

MOV ISP_CONTR, #00100000B ;SWBS = 0(Select AP area), SWRST = 1(Software reset)

;Software reset from user appliction program area (AP area) and switch to ISP area to run program

MOV ISP_CONTR, #01100000B ;SWBS = 1(Select ISP area), SWRST = 1(Software reset)

;Software reset from system ISP monitor program area (ISP area) and switch to ISP area to run program

MOV ISP_CONTR, #01100000B ;SWBS = 1(Select ISP area), SWRST = 1(Software reset)

This reset is to reset the whole system, all special function registers and I/O prots will be reset to the initial value

STC12LE5616AD Datasheet(PDF) 47 Page - STCmicro Technology Co,.Ltd

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