GD32F20x User Manual
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Table 1-3. Boot modes
Selected boot source
Boot mode selection pins
Boot1
Boot0
Main Flash Memory
x
0
System Memory
0
1
On-chip SRAM
1
1
After power-on sequence or a system reset, the
ARM® Cortex™-M3 processor fetches the
top-of-stack value from address 0x0000 0000 and the base address of boot code from 0x0000
0004 in sequence. Then, it starts executing code from the base address of boot code.
Due to the selected boot source, either the main flash memory (original memory space
beginning at 0x0800 0000) or the system memory (original memory space beginning at
0x1FFF B000) is aliased in the boot memory space which begins at the address 0x0000 0000.
When the on-chip SRAM whose memory space is beginning at 0x2000 0000 is selected as
the boot source, in the application initialization code, you have to relocate the vector table in
SRAM using the NVIC exception table and offset register.
The embedded boot loader is located in the System memory, which is used to reprogram the
Flash memory. In GD32F20x devices, the boot loader can be activated through the USART0
interface.
GD32F2 MCU embedded bootloader supports multi interfaces to update the Flash
memory.There will be one or two USART ports, and standard USB port can be used on
GD32F205xx and GD32F207xx connectivity line products. The details are shown in the
following
Table 1-4. Bootloader supported peripherals
Table 1-4. Bootloader supported peripherals
Products line
Products
Supported serial peripherals
Connectivity line
GD32F205xx
USART0(PA9 PA10)
USART1(PD5 PD6)
USB(PA9 PA10 PA11 PA12)
GD32F207xx
USART0(PA9 PA10)
USART1(PD5 PD6)
USB(PA9 PA10 PA11 PA12)
1.5.
Device electronic signature
Connectivity line devices (GD32F20X_CL) are GD32F205xx and GD32F207xx
microcontrollers which the flash memory density ranges from 256 to 3072 Kbytes.
The device electronic signature contains memory size information and the 96-bit unique
device ID. It is stored in the information block of the Flash memory. The 96-bit unique device
ID is unique for any device. It can be used as serial numbers, or part of security keys, etc.
Summary of Contents for GD32F20 Series
Page 191: ...GD32F20x User Manual 191 Bits Fields Descriptions 31 0 TRNDATA 31 0 32 Bit Random data ...
Page 290: ...GD32F20x User Manual 290 conversion is ongoing ...
Page 325: ...GD32F20x User Manual 325 15 0 ALRM 15 0 RTC alarm value low ...
Page 385: ...GD32F20x User Manual 385 ...
Page 523: ...GD32F20x User Manual 523 clears AERR bit by writing 0 to it ...