參數(shù)資料
型號(hào)： W78IRD2
廠商： WINBOND ELECTRONICS CORP
元件分類： 8位微控制器
英文描述： 8-BIT MICROCONTROLLER
中文描述： 8位微控制器
文件頁數(shù)： 52/76頁
文件大小： 646K
代理商： W78IRD2
W78IRD2/W78IRD2A
- 52 -
14. TIMED-ACCESS PROTECTION
The W78IRD2 has features like Timer clock selecting by setting CKCON, software reset and ISP
function that are crucial to the proper operation of the system. Consequently, The SFR CHPCON and
CKCON, which control the functions, have restricted write access to protect CPU from errant
operation. The W78IRD2 provides has a timed-access protection scheme that controls write access to
critical bits.
In this scheme, protected bits have a timed write-enable window. A write is successful only if this
window is active; otherwise, the write is discarded. The write-enable window is opened in two steps.
First, the software writes 87h to the register CHPENR. This starts a counter, which expires in three
machine cycles. Then, if the software writes 59h to CHPENR before the counter expires, the write-
enable window is opened for three machine cycles. After three machine cycles, the window
automatically closes, and the procedure must be repeated again to access protected bits.
The suggested code for opening the write-enable window is
CHPENR REG 0F6h ; Define new register CHPENR, located at 0F6h
MOV CHPENR, #87h
MOV CHPENR, #59h
Five examples, some correct and some incorrect, of using timed-access protection are shown below.
Example 1: Valid access
MOV CHPENR, #87h ;3 M/C, Note: M/C = Machine Cycles
MOV CHPENR, #59h ;3 M/C
MOV CKCON, #00h ;3 M/C
Example 2: Valid access
MOV CHPENR, #87h ;3 M/C
MOV CHPENR, #59h ;3 M/C
NOP ;1 M/C
SETB EWT ;2 M/C
Example 3: Valid access
MOV CHPENR, #87h ;3 M/C
MOV CHPENR, #59h ;3 M/C
ORL CKCON, #01h ;3M/C
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
W78IRD2A 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER
W78IRD2A25DL 功能描述:IC MCU 8-BIT 64K FLASH 40-DIP RoHS:是 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:W78 標(biāo)準(zhǔn)包裝:300 系列:78K0R/Ix3 核心處理器:78K/0R 芯體尺寸:16-位 速度:40MHz 連通性:3 線 SIO，I²C，LIN，UART/USART 外圍設(shè)備:DMA，LVD，POR，PWM，WDT 輸入/輸出數(shù):27 程序存儲(chǔ)器容量:16KB（16K x 8） 程序存儲(chǔ)器類型:閃存 EEPROM 大小:- RAM 容量:1K x 8 電壓 - 電源 (Vcc/Vdd):2.7 V ~ 5.5 V 數(shù)據(jù)轉(zhuǎn)換器:A/D 8x10b 振蕩器型:內(nèi)部 工作溫度:-40°C ~ 85°C 封裝/外殼:38-SSOP 包裝:托盤
W78IRD2A25PL 功能描述:IC MCU 8-BIT 64K FLASH 44-PLCC RoHS:是 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:W78 標(biāo)準(zhǔn)包裝:300 系列:78K0R/Ix3 核心處理器:78K/0R 芯體尺寸:16-位 速度:40MHz 連通性:3 線 SIO，I²C，LIN，UART/USART 外圍設(shè)備:DMA，LVD，POR，PWM，WDT 輸入/輸出數(shù):27 程序存儲(chǔ)器容量:16KB（16K x 8） 程序存儲(chǔ)器類型:閃存 EEPROM 大小:- RAM 容量:1K x 8 電壓 - 電源 (Vcc/Vdd):2.7 V ~ 5.5 V 數(shù)據(jù)轉(zhuǎn)換器:A/D 8x10b 振蕩器型:內(nèi)部 工作溫度:-40°C ~ 85°C 封裝/外殼:38-SSOP 包裝:托盤
W78J_1TG WAF 制造商:Fairchild Semiconductor Corporation 功能描述:
W78J_2G WAF 制造商:Fairchild Semiconductor Corporation 功能描述:
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