ST62T32BQ6 STMicroelectronics, ST62T32BQ6 Datasheet - Page 11

• Manufacturer Part Number: ST62T32BQ6
• Description: 8-bit Microcontrollers - MCU OTP EPROM 8K SPI/UAR
• Manufacturer: STMicroelectronics

Specifications of ST62T32BQ6

• Core: ST6
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 8 MHz
• Program Memory Size: 7948 B
• Data Ram Size: 192 B
• On-chip Adc: Yes
• Package / Case: PQFP-52
• Mounting Style: SMD/SMT
• A/d Bit Size: 8 bit
• A/d Channels Available: 21
• Interface Type: SPI, UART
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 30
• Number Of Timers: 2
• Program Memory Type: EPROM
• Factory Pack Quantity: 84
• Supply Voltage - Max: 5 V
• Supply Voltage - Min: 4.5 V

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
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.
Figure 6. Data read-only memory Window Memory Addressing
WINDOW REGISTER
ADDRESS:A19h
Figure 6
CONTENTS
DATA ROM
(DWR)
Example:
ROM
DWR=28h
below. For instance, when address-
13
7
12
6
0
0
11
5
1
1
10
4
0
0
9
3
1
1
8
2
0
0
7
1
0
0
0
0
1
0
1
0
6
0
5
5
0
0
Data Window Register (DWR)
Address: 0C9h — Write Only
Bits 7 = Not used.
Bit 6-0 = 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.
7
-
4
4
1
1
DWR6 DWR5 DWR4 DWR3 DWR2 DWR1 DWR0
3
3
1
1
2
2
0
0
1
1
0
0
0
0
1
1
PROGRAM SPACE ADDRESS
DATA SPACE ADDRESS
DATA SPACE ADDRESS
ST62T32B ST62E32B
IN INSTRUCTION
40h-7Fh
READ
59h
VR0A1573
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0