Boot Assist Module (BAM)
9-6
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
The BAM program uses SIU_CCR[DISNEX], which reflects the Nexus module state, to determine if the
serial password received in serial boot mode should be compared to:
•
Public password (0xFEED_FACE_CAFE_BEEF) if DISNEX is cleared
•
Flash password (64-bit value, stored in the shadow block of internal flash at address
0x00FF_FDD8) if DISNEX is set
NOTE
Regardless of the boot mode used, program a valid serial password. This
allows you to rescue the device using serial boot mode if the flash content
is corrupted.
Figure 9-3. Serial Boot Flash Password
9.5.3
Reset Configuration Half Word (RCHW)
The Reset Configuration Half Word defines boot options and must be programmed to predefined locations
in the internal flash or at the beginning of the external flash device. The 32 bit word after the RCHW must
be programmed with the user application’s starting address. The BAM passes control to the user
application at this starting address.
provides possible RCHW locations in the internal flash. When booting from the external flash
device, the RCHW must reside in the first 16 bit half word of the flash.
Flash Password@ 0x00FF_FDD8 – 0x00FF_FDDF
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
1
1
1
1
1
1
0
1
1
1
0
1
1
0
1
Serial Boot Password (0x00FF_FDD8) - 0xFEED (Factory Default)
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
1
1
1
1
0
1
0
1
1
0
0
1
1
1
0
Serial Boot Password (0x00FF_FDDA) - 0xFACE (Factory Default)
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
1
1
0
0
1
0
1
0
1
1
1
1
1
1
1
0
Serial Boot Password (0x00FF_FDDC) - 0xCAFE (Factory Default)
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
1
0
1
1
1
1
1
0
1
1
1
0
1
1
1
1
Serial Boot Password (0x00FF_FDDE) - 0xBEEF (Factory Default)
BOOT_BLOCK_ADDRESS
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
SWT
WTE
PS0
VLE
0
1
0
1
1
0
1
0
Boot Identifier = 0x5A
Figure 9-4. Reset Configuration Half Word
Summary of Contents for PXR4030
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