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GD32F20x User Manual
45
Table 2-1. GD32F20x_CL
Block
Name
Address Range
size
(bytes)
Main Flash Block
Page 0
0x0800 0000 - 0x0800 07FF
2KB
Page 1
0x0800 0800 - 0x0800 0FFF
2KB
Page 2
0x0800 1000 - 0x0800 17FF
2KB
Page 255
0x0807 F800 - 0x0807 FFFF
2KB
Page 256
0x0808 0000 - 0x0808 0FFF
4KB
Page 257
0x0808 1000 - 0x0808 1FFF
4KB
Page 895
0x082F F000 - 0x082F FFFF
4KB
Information
Block
GD32F20x_CL
Boot loader area
0x1FFF B000- 0x1FFF F7FF
18KB
Option bytes Block
Option bytes
0x1FFF F800 - 0x1FFF F80F
16B
Note:
The Information Block stores the boot loader. This block cannot be programmed or
erased by user.
2.3.2.
Read operations
The flash can be addressed directly as a common memory space. Any instruction fetch and
the data access from the flash are through the IBUS or DBUS from the CPU.
2.3.3.
Unlock the FMC_CTLx registers
After reset, the FMC_CTL0 register are not accessible in write mode, and the LK bit in
FMC_CTL0 register is 1. An unlocking sequence consists of two write operations to the
FMC_KEY0 register to open the access to the FMC_CTL0 register. The two write operations
are writing 0x45670123 and 0xCDEF89AB to the FMC_KEY0 register. After the two write
operations, the LK bit in FMC_CTL0 register is reset to 0 by hardware. The software can lock
the FMC_CTL0 again by setting the LK bit in FMC_CTL0 register to 1. Any wrong operations
to the FMC_KEY0 will set the LK bit to 1, and lock FMC_CTL0 register, and lead to a bus
error.
The OBPG bit and OBER bit in FMC_CTL0 are still protected even the FMC_CTL0 is
unlocked. The unlocking sequence is two write operations, which are writing 0x45670123 and
0xCDEF89AB to FMC_OBKEY register. And then the hardware sets the OBWEN bit in
FMC_CTL0 register to 1. The software can reset OBWEN bit to 0 to protect the OBPG bit and
OBER bit in FMC_CTL0 register again.
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 ...