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GD32F403xx User Manual
568
Memory
Access Mode
R/W
AHB
Transaction
Size
Memory
Transaction
Size
Comments
Async
W
8
16
Use of byte lanes
EXMC_NBL[1:0]
Async
R
16
16
Async
W
16
16
Async
R
32
16
Split into 2 EXMC
accesses
Async
W
32
16
Split into 2 EXMC
accesses
Sync
R
16
16
Sync
R
32
16
Sync
W
8
16
Use of byte lanes
EXMC_NBL[1:0]
Sync
W
16
16
Sync
W
32
16
SRAM and
ROM
Async
R
8
8
Async
R
8
16
Async
R
16
8
Split into 2 EXMC
accesses
Async
R
16
16
Async
R
32
8
Split into 4 EXMC
accesses
Async
R
32
16
Split into 2 EXMC
accesses
Async
W
8
8
Async
W
8
16
Use of byte lanes
EXMC_NBL[1:0]
Async
W
16
8
Async
W
16
16
Async
W
32
8
Async
W
32
16
NOR Flash/PSRAM controller timing
EXMC provides various programmable timing parameters and timing models for SRAM, ROM,
PSRAM, NOR Flash and other external static memory.
Table 21-4. NOR / PSRAM controller timing parameters
Parameter
Function
Access mode
Unit
Min
Max
CKDIV
Sync Clock divide ratio
Sync
HCLK
2
16
DLAT
Data latency
Sync
EXMC_CLK
2
17
BUSLAT
Bus latency
Async/Sync read
HCLK
1
16