GD32VF103 User Manual
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19.
External memory controller (EXMC)
19.1.
Overview
The external memory controller EXMC, is used as a translator for MCU to access a variety of
external memory, it automatically converts AMBA memory access protocol into a specific
memory access protocol defined in the configuration register, such as SRAM, ROM and NOR
Flash. Users could also tweak with the timing parameters in the configuration registers to
boost up memory access efficiency. EXMC access space is divided into multiple banks; each
bank is assigned to access a specific memory type with flexible parameter configuration as
defined in the control registers.
19.2.
Characteristics
Supported external memory:
–
SRAM
–
PSRAM
–
ROM
–
NOR Flash
Protocol translation between the AMBA and the multitude of external memory protocol.
Offering a variety of programmable
timing parameters to meet user’s specific needs.
Independent read/write timing configuration to a sub-set memory type.
8 or 16 bits bus width.
Address and data bus multiplexing mechanism for NOR Flash and PSRAM.
Write enable and byte select are provided as needed.
Automatic AMBA transaction split when internal and external bus width is not compatible.
19.3.
Function overview
19.3.1.
Block diagram
EXMC is the combination of four modules: The AHB bus interface, EXMC configuration
registers, NOR/PSRAM controller, AHB clock (HCLK) is the reference clock.