
DocID024597 Rev 5
457/1830
RM0351
Flexible static memory controller (FSMC)
471
Bits 29:28
ACCMOD[1:0]:
Access mode.
Specifies the asynchronous access modes as shown in the next timing diagrams.These bits are
taken into account only when the EXTMOD bit in the FMC_BCRx register is 1.
00: access mode A
01: access mode B
10: access mode C
11: access mode D
Bits 27:20 Reserved, must be kept at reset value
Bits 19:16
BUSTURN[3:0]
: Bus turnaround phase duration
The programmed bus turnaround delay is inserted between an asynchronous write transfer and
any other asynchronous /synchronous read or write transfer to or from a static bank. The bank can
be the same or different in case of read, in case of write the bank can be different expect for muxed
or mode D.
In some cases, whatever the programmed BUSTURN values, the bus turnaround delay is fixed as
follows:
• The bus turnaround delay is not inserted between two consecutive asynchronous write transfers
to the same static memory bank except for modes muxed and D.
• There is a bus turnaround delay of 2 HCLK clock cycle between:
–Two consecutive synchronous writes (burst or single) to the same bank.
–A synchronous write (burst or single) transfer and an asynchronous write or read transfer to or
from static memory bank.
• There is a bus turnaround delay of 3 HCLK clock cycle between:
–Two consecutive synchronous writes (burst or single) to different static bank.
–A synchronous write (burst or single) transfer and a synchronous read from the same or a
different bank.
0000: BUSTURN phase duration = 0 HCLK clock cycle added
...
1111: BUSTURN phase duration = 15 HCLK clock cycles added (default value after reset)
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
), used in asynchronous SRAM, PSRAM and NOR Flash memory accesses:
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)
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
), used in asynchronous multiplexed accesses:
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)
Note: In synchronous NOR Flash accesses, this value is not used, the address hold phase is always
1 Flash clock period duration.