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參數資料
| 型號： | W77E058A40FL |
| 廠商： | WINBOND ELECTRONICS CORP |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | 8-BIT MICROCONTROLLER |
| 中文描述： | 8-BIT, FLASH, 40 MHz, MICROCONTROLLER, PQFP44 |
| 封裝： | ROHS COMPLIANT, PLASTIC, QFP-44 |
| 文件頁數： | 47/87頁 |
| 文件大小： | 594K |
| 代理商： | W77E058A40FL |
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W77E058A
Publication Release Date: April 17, 2007
- 47 -
Revision A10
10. RESET CONDITIONS
The user has several hardware related options for placing the W77E058 into reset condition. In
general, most register bits go to their reset value irrespective of the reset condition, but there are a few
flags whose state depends on the source of reset. The user can use these flags to determine the
cause of reset using software. There are two ways of putting the device into reset state. They are
External reset and Watchdog reset.
10.1 External Reset
The device continuously samples the RST pin at state C4 of every machine cycle. Therefore the RST
pin must be held for at least 2 machine cycles to ensure detection of a valid RST high. The reset
circuitry then synchronously applies the internal reset signal. Thus the reset is a synchronous
operation and requires the clock to be running to cause an external reset.
Once the device is in reset condition, it will remain so as long as RST is 1. Even after RST is
deactivated, the device will continue to be in reset state for up to two machine cycles, and then begin
program execution from 0000h. There is no flag associated with the external reset condition. However
since the other two reset sources have flags, the external reset can be considered as the default reset
if those two flags are cleared.
The software must clear the POR flag after reading it, otherwise it will not be possible to correctly
determine future reset sources. If the power fails, i.e. falls below Vrst, then the device will once again
go into reset state. When the power returns to the proper operating levels, the device will again
perform a power on reset delay and set the POR flag.
10.2 Watchdog Timer Reset
The Watchdog timer is a free running timer with programmable time-out intervals. The user can clear
the watchdog timer at any time, causing it to restart the count. When the time-out interval is reached
an interrupt flag is set. If the Watchdog reset is enabled and the watchdog timer is not cleared, then
512 clocks from the flag being set, the watchdog timer will generate a reset . This places the device
into the reset condition. The reset condition is maintained by hardware for two machine cycles. Once
the reset is removed the device will begin execution from 0000h.
10.3 Reset State
Most of the SFRs and registers on the device will go to the same condition in the reset state. The
Program Counter is forced to 0000h and is held there as long as the reset condition is applied.
However, the reset state does not affect the on-chip RAM. The data in the RAM will be preserved
during the reset. However, the stack pointer is reset to 07h, and therefore the stack contents will be
lost. The RAM contents will be lost if the V
DD
falls below approximately 2V, as this is the minimum
voltage level required for the RAM to operate normally. Therefore after a first time power on reset the
RAM contents will be indeterminate. During a power fail condition, if the power falls below 2V, the
RAM contents are lost.
After a reset most SFRs are cleared. Interrupts and Timers are disabled. The Watchdog timer is
disabled if the reset source was a POR. The port SFRs have FFh written into them which puts the port
pins in a high state. Port 0 floats as it does not have on-chip pull-ups.
相關PDF資料 |
PDF描述 |
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| W77E058A40PL | 8-BIT MICROCONTROLLER |
| W77E058A | 8-BIT MICROCONTROLLER |
| W77E468F-25 | 8 BIT MICROCONTROLLER |
| W77E468F-40 | 8 BIT MICROCONTROLLER |
| W77E468 | 8 BIT MICROCONTROLLER |
相關代理商/技術參數 |
參數描述 |
|---|---|
| W77E058A40PL | 功能描述:IC MCU 8-BIT 32K FLASH 44-PLCC RoHS:是 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:W77 標準包裝:250 系列:56F8xxx 核心處理器:56800E 芯體尺寸:16-位 速度:60MHz 連通性:CAN，SCI，SPI 外圍設備:POR，PWM，溫度傳感器，WDT 輸入/輸出數:21 程序存儲器容量:40KB（20K x 16） 程序存儲器類型:閃存 EEPROM 大小:- RAM 容量:6K x 16 電壓 - 電源 (Vcc/Vdd):2.25 V ~ 3.6 V 數據轉換器:A/D 6x12b 振蕩器型:內部 工作溫度:-40°C ~ 125°C 封裝/外殼:48-LQFP 包裝:托盤 配用:MC56F8323EVME-ND - BOARD EVALUATION MC56F8323 |
| W77E11 | 制造商:OMRON INDUSTRIAL AUTOMATION 功能描述:EXECUTION EX. NO.1 DX CODE ZA |
| W77E468 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8 BIT MICROCONTROLLER |
| W77E468F-25 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8 BIT MICROCONTROLLER |
| W77E468F-40 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8 BIT MICROCONTROLLER |
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