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参数资料
| 型号： | ST624XB-KIT |
| 英文描述： | STARTER KIT DATASHEET FOR ST624X |
| 中文描述： | 入门套件小册子的ST624X |
| 文件页数： | 11/74页 |
| 文件大小： | 733K |
| 代理商： | ST624XB-KIT |
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11/74
ST62T46B/E46B
MEMORY MAP
(Cont’d)
1.3.5 Data Window Register (DWR)
The Data read-only memory window is located from
address 0040h to address 007Fh in Data space. It
allows direct reading of 64 consecutive bytes locat-
ed anywhere in program memory, between ad-
dress 0000h and 1FFFh (top memory address de-
pends on the specific device). All the program
memory can therefore be used to store either in-
structions or read-only data. Indeed, the window
can be moved in steps of 64 bytes along the pro-
gram memory by writing the appropriate code in the
Data Window Register (DWR).
The DWR can be addressed like any RAM location
in the Data Space, it is however a write-only regis-
ter and therefore cannot be accessed using single-
bit operations. This register is used to position the
64-byte read-only data window (from address 40h
to address 7Fh of the Data space) in program
memory in 64-byte steps. The effective address of
the byte to be read as data in program memory is
obtained by concatenating the 6 least significant
bits of the register address given in the instruction
(as least significant bits) and the content of the
DWR register (as most significant bits), as illustrat-
ed in
Figure 5
below. For instance, when address-
ing location 0040h of the Data Space, with 0 load-
ed in the DWR register, the physical location ad-
dressed in program memory is 00h. The DWR reg-
ister is not cleared on reset, therefore it must be
written to prior to the first access to the Data read-
only memory window area.
Data Window Register (DWR)
Address: 0C9h
—
Write Only
Bits 6, 7 = Not used.
Bit 5-0 =
DWR5-DWR0:
Data read-only memory
Window Register Bits.
These are the Data read-
only memory Window bits that correspond to the
upper bits of the data read-only memory space.
Caution:
This register is undefined on reset. Nei-
ther read nor single bit instructions may be used to
address this register.
Note:
Care is required when handling the DWR
register as it is write only. For this reason, the
DWR contents should not be changed while exe-
cuting an interrupt service routine, as the service
routine cannot save and then restore the register’s
previous contents. If it is impossible to avoid writ-
ing to the DWR during the interrupt service routine,
an image of the register must be saved in a RAM
location, and each time the program writes to the
DWR, it must also write to the image register. The
image register must be written first so that, if an in-
terrupt occurs between the two instructions, the
DWR is not affected.
Figure 5. Data read-only memory Window Memory Addressing
7
0
-
-
DWR5 DWR4 DWR3 DWR2 DWR1 DWR0
DATA ROM
WINDOW REGISTER
CONTENTS
(DWR)
DATA SPACE ADDRESS
40h-7Fh
IN INSTRUCTION
PROGRAM SPACE ADDRESS
READ
7
6
5
4
3
2
0
5
4
3
2
1
0
5
4
3
2
1
0
1
6
7
8
9
10
11
0
1
VR01573C
12
1
0
DATA SPACE ADDRESS
59h
:
:
0
0
0
0
1
0
0
1
1
1
Example:
DWR=28h
1
1
0
0
0
0
0
0
0
1
ROM
ADDRESS:A19h
1
1
13
0
1
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ST624XB-KIT/110 | 功能描述:开发板和工具包 - 其他处理器 ST624X Starter Kit RoHS:否 制造商:Freescale Semiconductor 产品:Development Systems 工具用于评估:P3041 核心:e500mc 接口类型:I2C, SPI, USB 工作电源电压: |
| ST624XB-KIT/UK | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:ST62 KIT |
| ST6252 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:8-BIT OTP/EPROM MCUs WITH A/D CONVERTER, AUTO-RELOAD TIMER AND EEPROM |
| ST6252BB1 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:8-BIT OTP/EPROM MCUs WITH A/D CONVERTER, AUTO-RELOAD TIMER AND EEPROM |
| ST6252BB1/XXX | 制造商:未知厂家 制造商全称:未知厂家 功能描述:8-Bit Microcontroller |
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