Nations Technologies Inc.
Tel
:
+86-755-86309900
:
info@nationstech.com
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
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/
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byte BOOT configuration. After a system reset or exit from standby mode, the value of the BOOT pin will be re-
latched and the option byte boot configuration (USER2) will be re-read. After a startup delay, the CPU gets the
address at the top of the stack from address 0x0000_0000 and executes the code from the reset vector address
indicated by address 0x0000_0004.Because of the Cortex™-M4 always gets the stack top pointer and reset vector
from addresses 0x0000_0000 and 0x0000_0004, so boot is only suitable for starting from the CODE area, and address
remapping is designed for boot space. There are three boot modes to choose from:
Boot from Main Flash:
Main flash memory is mapped to the boot space (0x0000_0000);
Main flash memory is accessible in two address areas, 0x0000_0000 or 0x0800_0000
(
ICode/DCode/DMA
)
;
Boot from System Memory:
System memory is mapped to boot space (0x0000_0000);
System memory can be accessed in two address areas, 0x0000_0000 or 0x1FFF_0000
(
ICode/DCode/DMA
)
;
Boot from the built-in SRAM:
The built-in SRAM is mapped to boot space (0x0000_0000);
The built-in SRAM is accessible in two address areas, 0x0000_0000 or 0x2000_0000
(
ICode/DCode/SBus/DMA
)
;
Boot configuration
In addition, SRAM can also be accessed through virtual address segment 0x1000_0000, which makes the CPU jump
to SRAM to run programs through ICode/DCode after starting from Main Flash or System Memory (note that
programs are not started from SRAM and do not belong to startup mode). In addition to the BOOT pin configuration
boot program, there are two ways to run the program in SRAM:
Jump directly to the physical address segment 0x2000_0000 of SRAM to run the program. At this time, the
program will be run through SBus.
Jump to the virtual address segment 0x1000_0000 of SRAM, and internally remap to the physical address
segment 0x2000_0000 to run the program. At this time, the program will run efficiently through ICode/DCode.
Table 2-2 List of boot mode
Boot mode select pin
Boot mode
Specifies the start address for accessing
memory space in boot mode
nBOOT1
nBOOT0
BOOT0 pin
nSWBOOT0
Main Flash
System
Memory
SRAM
X
X
0
1
Main Flash start
0x0000_0000
0x0800_0000
0x1FFF_0000
0x2000 0000
0x1000 0000
X
1
X
0
1
X
1
1
System Memory
Start
0x08000000
0x0000_0000
0x1FFF_0000
0x2000 0000
0x1000 0000
1
0
X
0