Embedded Flash memory
RM0365
71/1080
DocID025202 Rev 7
4.5 Flash
register description
The Flash memory registers have to be accessed by 32-bit words (half-word and byte
accesses are not allowed).
4.5.1 Flash
access
control
register (FLASH_ACR)
Address offset: 0x00
Reset value: 0x0000 0030
4.5.2
Flash key register (FLASH_KEYR)
Address offset: 0x04
Reset value: xxxx xxxx
These bits are all write-only and return a 0 when read.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
PRFT
BS
PRFT
BE
HLF
CYA
LATENCY[2:0]
r
rw
rw
rw
rw
rw
Bits 31:6 Reserved, must be kept at reset value.
Bit 5
PRFTBS
: Prefetch buffer status
This bit provides the status of the prefetch buffer.
0: Prefetch buffer is disabled
1: Prefetch buffer is enabled
Bit 4
PRFTBE
: Prefetch buffer enable
0: Prefetch is disabled
1: Prefetch is enabled
Bit 3
HLFCYA:
Flash half cycle access enable
0: Half cycle is disabled
1: Half cycle is enabled
Bits 2:0
LATENCY[2:0]
: Latency
These bits represent the ratio of the HCLK period to the Flash access time.
000: Zero wait state, if 0 < HCLK
≤
24 MHz
001: One wait state, if 24 MHz < HCLK
≤
48 MHz
010: Two wait sates, if 48 < HCLK
≤
72 MHz
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
FKEYR[31:16]
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FKEYR[15:0]
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
Bits 31:0
FKEYR
: Flash key
These bits represent the keys to unlock the Flash.