STMicroelectronics STM32F405 Reference Manual page 1632

Flexible memory controller (FMC)
Bits 15:8 DATAST[7:0]: Data-phase duration
These bits are written by software to define the duration of the data phase (refer to
to
0000 0000: Reserved
0000 0001: DATAST phase duration = 1 × HCLK clock cycles
0000 0010: DATAST phase duration = 2 × HCLK clock cycles
...
1111 1111: DATAST phase duration = 255 × HCLK clock cycles (default value after reset)
For each memory type and access mode data-phase duration, please refer to the respective
figure
Example: Mode1, write access, DATAST=1: Data-phase duration= DATAST+1 = 2 HCLK clock
cycles.
Note: In synchronous accesses, this value is don't care.
Bits 7:4 ADDHLD[3:0]: Address-hold phase duration
These bits are written by software to define the duration of the address hold phase (refer to
Figure 465
0000: Reserved
0001: ADDHLD phase duration =1 × HCLK clock cycle
0010: ADDHLD phase duration = 2 × HCLK clock cycle
...
1111: ADDHLD phase duration = 15 × HCLK clock cycles (default value after reset)
For each access mode address-hold phase duration, please refer to the respective figure
(Figure 465
Note: In synchronous accesses, this value is not used, the address hold phase is always 1
Bits 3:0 ADDSET[3:0]: Address setup phase duration
These bits are written by software to define the duration of the address setup phase (refer to
Figure 456
accesses:
0000: ADDSET phase duration = 0 × HCLK clock cycle
...
1111: ADDSET phase duration = 15 × HCLK clock cycles (default value after reset)
For each access mode address setup phase duration, please refer to the respective figure
(refer to
Note: In synchronous accesses, this value is don't care.
Note: PSRAMs (CRAMs) have a variable latency due to internal refresh. Therefore these
memories issue the NWAIT signal during the whole latency phase to prolong the latency as
needed.
With PSRAMs (CRAMs) the filled DATLAT must be set to 0, so that the FMC exits its latency
phase soon and starts sampling NWAIT from memory, then starts to read or write when the
memory is ready.
This method can be used also with the latest generation of synchronous Flash memories
that issue the NWAIT signal, unlike older Flash memories (check the datasheet of the
specific Flash memory being used).
1632/1731
Figure 468), used in asynchronous accesses:
(Figure 456 to Figure
to Figure 468), used in mode D or multiplexed accesses:
to Figure 468).
memory clock period duration.
to Figure 468), used in SRAMs, ROMs and asynchronous NOR Flash and PSRAM
Figure 456 to Figure
In Muxed mode or Mode D, the minimum value for ADDSET is 1.
DocID018909 Rev 11
468).
468).
RM0090
Figure 456