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參數(shù)資料
| 型號： | MD80C52CXXX-12P883 |
| 廠商： | ATMEL CORP |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | 8-BIT, MROM, 12 MHz, MICROCONTROLLER, CDIP40 |
| 封裝： | 0.600 INCH, CERAMIC, DIP-40 |
| 文件頁數(shù)： | 203/287頁 |
| 文件大?。?/td> | 12910K |
| 代理商： | MD80C52CXXX-12P883 |
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281
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
26.4
Read-While-Write and No Read-While-Write Flash Sections
Whether the CPU supports Read-While-Write or if the CPU is halted during a Boot Loader soft-
ware update is dependent on which address that is being programmed. In addition to the two
sections that are configurable by the BOOTSZ Fuses as described above, the Flash is also
divided into two fixed sections, the Read-While-Write (RWW) section and the No Read-While-
Write (NRWW) section. The limit between the RWW- and NRWW sections is given in Table 26-
1 and Figure 26-1 on page 282. The main difference between the two sections is:
When erasing or writing a page located inside the RWW section, the NRWW section can be
read during the operation
When erasing or writing a page located inside the NRWW section, the CPU is halted during the
entire operation
Note that the user software can never read any code that is located inside the RWW section dur-
ing a Boot Loader software operation. The syntax “Read-While-Write section” refers to which
section that is being programmed (erased or written), not which section that actually is being
read during a Boot Loader software update.
26.4.1
RWW – Read-While-Write Section
If a Boot Loader software update is programming a page inside the RWW section, it is possible
to read code from the Flash, but only code that is located in the NRWW section. During an on-
going programming, the software must ensure that the RWW section never is being read. If the
user software is trying to read code that is located inside the RWW section (that is, by load pro-
gram memory, call, or jump instructions or an interrupt) during programming, the software might
end up in an unknown state. To avoid this, the interrupts should either be disabled or moved to
the Boot Loader section. The Boot Loader section is always located in the NRWW section. The
RWW Section Busy bit (RWWSB) in the Store Program Memory Control and Status Register
(SPMCSR) will be read as logical one as long as the RWW section is blocked for reading. After
a programming is completed, the RWWSB must be cleared by software before reading code
located in the RWW section. See Section “26.9.1” on page 296 for details on how to clear
RWWSB.
26.4.2
NRWW – No Read-While-Write Section
The code located in the NRWW section can be read when the Boot Loader software is updating
a page in the RWW section. When the Boot Loader code updates the NRWW section, the CPU
is halted during the entire Page Erase or Page Write operation.
Table 26-1.
Read-while-write features.
Which section does the Z-pointer
address during the programming?
Which section can be
read during
programming?
Is the CPU
halted?
Read-while-write
supported?
RWW Section
NRWW Section
No
Yes
NRWW Section
None
Yes
No
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MQ80C32E-12:D | 8-BIT, 12 MHz, MICROCONTROLLER, CQFP44 |
| MQ80C52CXXX-16SBR | 8-BIT, MROM, 16 MHz, MICROCONTROLLER, CQFP44 |
| MT80C31-20D | 8-BIT, 20 MHz, MICROCONTROLLER, PQFP44 |
| MD80C32E-16SC | 8-BIT, 16 MHz, MICROCONTROLLER, CDIP40 |
| MQ80C52TXXX-16SB | 8-BIT, MROM, 16 MHz, MICROCONTROLLER, CQFP44 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MD80C86 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:CMOS 16-Bit Microprocessor |
| MD80C862 | 制造商:Intel 功能描述:PROCESSOR:MICRO-PROCESSOR |
| MD80C86-2 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:CMOS 16-Bit Microprocessor |
| MD80C86-2/883 | 制造商:Intersil Corporation 功能描述:MPU 16BIT CMOS 8MHZ 40CDIP - Rail/Tube 制造商:Rochester Electronics LLC 功能描述:CPU 16BILT 5V CMOS 8MHZ 40CDIP - Bulk |
| MD80C86-2/B | 制造商:Intersil Corporation 功能描述:MPU 16BIT CMOS 8MHZ 40CDIP - Rail/Tube |
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