GD32F20x User Manual
710
controller
Chip Enable
(EXMC_NCE)
EXMC_NREG
EXMC_NIORD
EXMC_NIOWR
Clock
(EXMC_CLK)
Address
(EXMC_A[25:0])
EXMC_NWR
EXMC_NOE
Write Data
Read Data
C 1 HCLK
COMHIZx HCLK
CO 1 HCLK
COMHLDx HCLK
Valid
NAND flash operation
When EXMC sends command or address to NAND Flash, it needs to use the command latch
signal (A [16]) or address latch signal (EXMC_A [17]), namely, the CPU needs to perform
write operation in particular address.
Example: NAND Flash read operation steps:
1. Configure EXMC_NPCTLx and EXMC_NPCTCFGx register. When pre-waiting is needed,
EXMC_NPATCFGx has to be configured.
2.
Send the command of NAND Flash read operation to the common space. Namely, during
the valid period of EXMC_NCE and EXMC_NWE, when EXMC_CLE (EXMC_A [16])
becomes valid (high level), data on the I/O pins is regarded as a command by NAND
Flash.
3.
Send the start address of read operation to the common space. During the valid period
of EXMC_NCE and EXMC_NWE, when EXMC_ALE (EXMC_A [17]) becomes valid
(high level), the data on the I/O pins is regarded as an address by NAND Flash.
4.
Waiting for NAND ready signal. In this period, NAND controller will maintain EXMC_NCE
valid.
5.
Read data byte by byte from the data area of the common space.
6.
If new commands or address haven’t been written, data of the next page can be read
out automatically. You can also read the data of the next page by going to step 3 and
then writing a new address or writing a new command and address in step 2.
NAND flash pre-wait functionality
Some NAND Flash requires that the controller should wait for NAND Flash to be ready, after
the first command byte and following the address bytes are send, and some EXMC_NCE-
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 ...