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GD32F403xx User Manual
569
Parameter
Function
Access mode
Unit
Min
Max
DSET
Data setup time
Async
HCLK
2
256
AHLD
Address hold time
Async(muxed)
HCLK
2
16
ASET
Address setup time
Async
HCLK
1
16
Table 21-5. EXMC_timing models
Timing
model
Extend
mode
Mode description
Write timing
parameter
Read timing
parameter
Async
Mode 1
0
SRAM/PSRAM/CRAM
DSET
ASET
DSET
ASET
Mode 2
0
NOR Flash
DSET
ASET
DSET
ASET
Mode A
1
SRAM/PSRAM/CRAM with
EXMC_NOE toggling on data
phase
WDSET
WASET
DSET
ASET
Mode B
1
NOR Flash
WDSET
WASET
DSET
ASET
Mode C
1
NOR Flash with EXMC_NOE
toggling on data phase
WDSET
WASET
DSET
ASET
Mode D
1
With address hold capability
WDSET
WAHLD
WASET
DSET
AHLD
ASET
Mode AM
0
NOR Flash address/data mux
DSET
AHLD
ASET
BUSLAT
DSET
AHLD
ASET
BUSLAT
Sync
Mode E
0
NOR/PSRAM/CRAM
synchronous read
PSRAM/CRAM
synchronous write
DLAT
CKDIV
DLAT
CKDIV
Mode SM
0
NOR Flash address/data mux
DLAT
CKDIV
DLAT
CKDIV
Table 21-5. EXMC_timing models
, EXMC NOR Flash / PSRAM controller
provides a variety of timing model, users can modify those parameters listed in
NOR / PSRAM controller timing parameters
to satisfy different external memory type and
user’s requirements. When extended mode is enabled via the EXMODEN bit in
EXMC_SNCTLx register, different timing patterns f or read and write access could be
generated independently according to EXMC_SNTCFGx and EXMC_SNWTCFGx register’s
conf iguration.
Asynchronous access timing diagram
Mode 1 - SRAM/CRAM