DocID018909 Rev 11
99/1731
RM0090
Embedded Flash memory interface
112
3.9.2 Flash
access
control
register (FLASH_ACR)
for STM32F42xxx and STM32F43xxx
The Flash access control register is used to enable/disable the acceleration features and
control the Flash memory access time according to CPU frequency.
Address offset: 0x00
Reset value: 0x0000 0000
Access: no wait state, word, half-word and byte access
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Reserved
DCRST ICRST DCEN
ICEN
PRFTEN
Reserved
LATENCY[2:0]
rw
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rw
rw
rw
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Bits 31:11 Reserved, must be kept cleared.
Bit 12
DCRST:
Data cache reset
0: Data cache is not reset
1: Data cache is reset
This bit can be written only when the D cache is disabled.
Bit 11
ICRST:
Instruction cache reset
0: Instruction cache is not reset
1: Instruction cache is reset
This bit can be written only when the I cache is disabled.
Bit 10
DCEN:
Data cache enable
0: Data cache is disabled
1: Data cache is enabled
Bit 9
ICEN:
Instruction cache enable
0: Instruction cache is disabled
1: Instruction cache is enabled
Bit 8
PRFTEN:
Prefetch enable
0: Prefetch is disabled
1: Prefetch is enabled
Bits 7:4 Reserved, must be kept cleared.
Bits 3:0
LATENCY[2:0]:
Latency
These bits represent the ratio of the CPU clock period to the Flash memory access time.
0000: Zero wait state
0001: One wait state
0010: Two wait states
...
1110: Fourteen wait states
1111: Fifteen wait states