GD32F20x User Manual
682
automatically split into several continuous memory accesses.
When the width of AHB bus is smaller than memory bus width. If the external memory devices
have the byte selection function, such as SRAM, ROM. PSRAM, SDRAM, the application can
access the corresponding byte through their byte lane EXMC_NBL[1:0]. Otherwise, write
operation is prohibited, but read operation is allowed unconditionally. (See
Bank1/2/3 of EXMC support the memory and access mode
25.3.3.
External device address mapping
Figure 25-2. EXMC memory banks
Bank0(4x64M)
Bank1(256M)
Bank2(256M)
Bank3(256M)
0x6000 0000
0x6FFF FFFF
0x7000 0000
0x7FFF FFFF
0x8000 0000
0x9FFF FFFF
0x8FFF FFFF
0x9000 0000
Address
Banks
Supported memory type
SDRAM Device0
(256M)
SDRAM Device1
(256M)
0xC000 0000
0xCFFF FFFF
0xD000 0000
0xDFFF FFFF
SDRAM
NAND
PC Card
NOR/PSRAM
SQPI-PSRAM
EXMC access space is divided into multiple banks. Each bank is 256 Mbytes. The first bank
(Bank0) is further divided into four Regions, and each Region is 64 Mbytes. Bank1 and Bank2
is each divided into two spaces, the attribute memory space and the common memory space.
Bank3 is divided into three spaces, which are the attribute memory space, the common
memory space and the I/O memory space.
Each bank or region has a separate chip-select control signal, which can be configured
independently.
Bank0 is used for NOR and PSRAM device access.
Содержание GD32F20 Series
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Страница 191: ...GD32F20x User Manual 191 Bits Fields Descriptions 31 0 TRNDATA 31 0 32 Bit Random data ...
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Страница 325: ...GD32F20x User Manual 325 15 0 ALRM 15 0 RTC alarm value low ...
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Страница 523: ...GD32F20x User Manual 523 clears AERR bit by writing 0 to it ...