GigaDevice Semiconductor GD32F10 Series, User Manual

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GD32F10x User Manual
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16-bit access operation is being performed. EXMC_NIOWR and EXMC_NIORD dictate
whether the on-going operation is a write or read operation, and EXMC_NREG is low
during IO space access.
AHB access on 16-bit PC/CF card:
1. Common space: It is usually where data are stored, it could be accessible either in byte
or in half-word mode, and odd address access is not supported in byte mode. When AHB
word access is selected, EXMC automatically splits it into 2 consecutive half-word
access. EXMC_NREG is high when common memory is targeted. EXMC_NOE and
EXMC_NWE are the read and write enable signal for this type of access.
2. Attribute space: It is usually where configuration information are stored, for byte AHB
access, only even address is possible. Half-word access converts into a single byte
access automatically, and word access is converted into two consecutive byte access
where only the even bytes are operational. In both half-word and word access, only
EXMC_NCE3_0 will be active. EXMC_NREG is low when attribute memory is targeted.
EXMC_NOE and EXMC_NWE are the read and write enable signal for this type of
access.
3. IO space: Both byte and half-word AHB access are supported, in IO space memory
access, EXMC_NIORD and EXMC_NIOWR act as the read and write enable signal
respectively.