GD32F20x User Manual
709
Memory
Mode
R/W
AHB transaction size
Comments
Async
W
16
Async
R
32
Automatically split into 2 EXMC
accesses
Async
W
32
NAND flash or PC card controller timing
EXMC can generate the appropriate signal timing for NAND Flash, PC Cards and other
devices. Each bank has a corresponding register to manage and control the external memory,
such as EXMC_NPCTLx, EXMC_NPINTENx, EXMC_NPCTCFGx, EXMC_NPATCFGx,
EXMC_PIOTCFG3 and EXMC_NECCx. Among these registers, EXMC_NPCTCFGx,
EXMC_NPATCFGx, EXMC_PIOTCFG3 registers contain four timing parameters individually
which are configured according to user specification and features of the external memory.
Table 25-20. NAND flash or PC card programmable parameters
Programmable parameter
W/R
Unit
Functional description
NAND Flash/
PC Card
Min
Max
High impedance time of the
memory data bus
(
HIZ
)
W/R
HCLK
Time to keep the data bus high
impedance after starting write
operation
0
255
Memory hold time
(
HLD
)
W/R
HCLK
The number of HCLK clock
cycles to keep address valid
after sending the command. In
write mode, it is also data hold
time.
1
255
Memory wait time
(
WAIT
)
W/R
HCLK
Minimum duration of sending
command
1
256
Memory setup time
(
SET
)
W/R
HCLK
The number of HCLK clock
cycles to build address before
sending command
1
256
The figure below shows the programmable parameters which are defined in the common
memory space operations. The programmable parameters of Attribute memory space or I/O
memory space (only for PC Card) are defined as well.
Figure 25-27. Access timing of common memory space of NAND flash or PC card
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 ...