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GD32F20x User Manual
689
Memory
Access Mode
R/W
AHB
Transaction
Size
Memory
Transaction
Size
Comments
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 25-6. 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
DSET
Data setup time
Async
HCLK
2
256
AHLD
Address hold time
Async(muxed)
HCLK
1
16
ASET
Address setup time
Async
HCLK
1
16
Table 25-7. 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_OE toggling on data
phase
WDSET
WASET
DSET
ASET
Mode B
1
NOR Flash
WDSET
WASET
DSET
ASET
Mode C
1
NOR Flash with EXMC_OE
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
Summary of Contents for GD32F20 Series
Page 191: ...GD32F20x User Manual 191 Bits Fields Descriptions 31 0 TRNDATA 31 0 32 Bit Random data ...
Page 290: ...GD32F20x User Manual 290 conversion is ongoing ...
Page 325: ...GD32F20x User Manual 325 15 0 ALRM 15 0 RTC alarm value low ...
Page 385: ...GD32F20x User Manual 385 ...
Page 523: ...GD32F20x User Manual 523 clears AERR bit by writing 0 to it ...