GD32F20x User Manual
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sensitive NAND Flash also requires that the EXMC_NCE must remain valid before it is ready.
Taking TOSHIBA128 M x 8 bit NAND Flash as an example:
Figure 25-28
. Access to none "NCE don’t care" NAND Flash
Address Latch
Enable
(EXMC_A[17])
Write Enable
(EXMC_NWE)
Chip Enable
(EXMC_NCE)
Command Latch
Enable
(EXMC_A[16])
Output Enable
(EXMC_NOE)
Data
(EXMC_D[7:0])
Ready
(EXMC_INT[x])
tWB
tR
CMD 0
(00h)
CMD 1
30h
ADD 0
(CA0-7)
ADD 1
(CA8-11)
ADD 2
(PA0-7)
ADD 3
(PA8-15)
1. Write CMD0 into NAND Flash bank common space command area.
2.
Write ADD0 into NAND Flash bank common space address area.
3.
Write ADD1 into NAND Flash bank common space address area.
4.
Write ADD2 into NAND Flash bank common space address area.
5.
Write ADD3 into NAND Flash bank common space address area.
6.
Write CMD1 into NAND Flash bank attribute space command area.
In step 6, EXMC uses the operation timing defined in EXMC_NPATCFGx register. After a
period of ATTHLD, NAND Flash waits for EXMC_INTx signal to be busy, and the time period
of ATTHLD should be greater than tWB (tWB is defined as the time from EXMC_NWE high
to EXMC_INTx low). For NCE-sensitive NAND Flash, after the first command byte following
address bytes has been entered, EXMC_NCE must remain low until EXMC_INTx goes from
low to high. The ATTHLD value of attribute space can be set in EXMC_NPATCFGx register
to meet the timing requirements of tWB. MCU can use the attribute space timing when writing
the first command byte following address bytes to the NAND Flash device. In other times, the
MCU must use the common space timing.
NAND flash ECC calculation module
An ECC calculation hardware is implemented in bank1 and bank2 respectively. Users can
choose page size according to the ECCSZ control field in the EXMC_NPCTLx register. ECC
offers one bit error correction and two bits errors detection.
When NAND memory block is enabled, ECC module will detect EXMC_D[15:0], EXMC_NCE
and EXMC_NWE signals. When a data size of ECCSZ has been read or written, software
must read the calculated ECC in theEXMC_NECCx register. When a recalculation of ECC is
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 ...