www
.mcu.com.cn
12
/
239
Rev.
1.00
CMS80F731x Reference Manual
1.
Central Processing Unit (CPU)
This series is a microcontroller with 8-bit 8051 frame structure. The CPU is the core component of the microcontroller, which
is composed of arithmetic units, controllers, and special register groups. The arithmetic unit module mainly implements data
arithmetic and logic operations, bit variable processing and data transfer operations; the controller module mainly decodes
instructions, and then sends out various control signals; the special register group is mainly used to indicate the memory address
of the current instruction to be executed , Store the operand and indicate the state after the instruction is executed. The special
register group mainly includes accumulatorACC, general register B, stack pointer SP, data pointer DPTR, Program status
registerPSW, Program counterPC, etc.
1.1
Reset Vector (0000H)
The microcontroller has a word-long system reset vector (0000H), after which the program will restart execution at 0000H
and the system registers will revert to their default values. The following program demonstrates how to define a reset vector in
FLASH.
Example: Define a reset vector
ORG
0000H
; System reset vector
LJMP
START
ORG
0010H
; The user program starts
START:
…
; User programs
…
END
; The program ends
1.2
BOOT Partition
The size of the program area space is 16K*8Bit, where the program is divided into BOOT area and APROM area, and the
BOOT area size is allocated by the user configuration register.
When the chip is powered on, if the program is started from the BOOT area, it needs to be satisfied: the address space
allocation method is 1/2/3 (set BOOT_1K/BOOT_2K/BOOT_4K through CONFIG), otherwise the program will be launched from
the APROM area.
Take the 1K space in the BOOT area as an example: confIG configuration BOOT_1K, after the chip is powered on
configuration, the program starts running from address 3C00H. If the program needs to switch between the BOOT region and
the APROM region, it is necessary to write a 0xAA/0x55 to the BOOT region control register BOOTCON (see register description
for details), and then perform a software reset or generate a watchdog reset.
When power-on reset, external reset, voltage reset, bootcon reset value is 0x00, software reset and watchdog reset can
not clear the register.
