GD32F403xx User Manual
580
Table 21-11. Multiplex mode related registers configuration
Bit Position
Bit Name
Reference Setting Value
EXMC_SNCTLx
31-20
Reserved
0x000
19
SYNCWR
0x0
18-16
CPS
0x0
15
ASYNCWTEN
Depends on memory
14
EXMODEN
0x0
13
NRWTEN
0x0
12
WEN
Depends on memory
11
NRWTCFG
No effect
10
WRAPEN
0x0
9
NRWTPOL
Meaningful only when the bit 15 is set to 1
8
SBRSTEN
0x0
7
Reserved
0x1
6
NREN
0x1
5-4
NRW
Depends on memory
3-2
NRTP
0x2:NOR Flash
1
NRMUX
0x1
0
NRBKEN
0x1
EXMC_SNTCFGx
31-30
Reserved
0x0
29-28
ASYNCMOD
0x0
27-24
DLAT
No effect
23-20
CKDIV
No effect
19-16
BUSLAT
Minimum time between EXMC_NE[x] rising edge
to EXMC_NE[x] falling edge
15-8
DSET
Depends on memory and user (DSET+2 HCLK for
write, DSET+3 HCLK for read)
7-4
AHLD
Depends on memory and user
3-0
ASET
Depends on memory and user
Wait timing of asynchronous communication
Wait f eature is controlled by the bit ASYNCWAIT in register EXMC_SNCTLx. During extern
memory access, data setup phase will be automatically extended by the active
EXMC_NWAIT signal if ASYNCWAIT bit is set. The extend time is calculated as follows:
If memory wait signal is aligned to EXMC_NOE/ EXMC_NWE:
T
DATA_SETUP
≥ maxT
WAIT_ASSERTION
+4HCLK (21-1)
If memory wait signal is aligned to EXMC_NE:
If