GD32F403xx User Manual
581
maxT
WAIT_ASSERTION
≥ T
ADDRES_PHASE
+ T
HOLD_PHASE
(21-2)
be
T
DATA_SETUP
≥(maxT
WAIT_ASSERTION
-T
ADDRES_PHASE
-T
HOLD_PHASE
)+4HCLK (21-3)
Otherwise
T
DATA_SETUP
≥ 4HCLK (21-4)
Figure 21-19. Read access timing diagram under async-wait signal assertion
Address
(EXMC_A[25:0])
Wait
(EXMC_NWAIT)
NRWTPOL = 0
Chip Enable
(EXMC_NEx)
Output Enable
(EXMC_NOE)
Data
(EXMC_D[15:0])
Address Setup Time
Data Setup Time
Memory Output
4 HCLK
Wait
(EXMC_NWAIT)
NRWTPOL = 1
2 HCLK
Data sampling point
Figure 21-20. Write access timing diagram under async-wait signal assertion
Address
(EXMC_A[25:0])
Wait
(EXMC_NWAIT)
NRWTPOL = 0
Chip Enable
(EXMC_NEx)
Write Enable
(EXMC_NWE)
Data
(EXMC_D[15:0])
Address Setup Time
Data Setup Time
3 HCLK
EXMC Output
1 HCLK
Wait
(EXMC_NWAIT)
NRWTPOL = 1
Synchronous access timing diagram
The relations between memory clock (EXMC_CLK) and system clock (HCLK) clock are as
f ollows:
EXMC_CLK=
HCLK
CKDIV+1
(21-5)
CKDIV is the synchronous clock divider ratio, it is configured through the CKDIV control field