PXR40RM Datasheet, PDF (285/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

Boot Assist Module (BAM)
Table 9-3. Boot Modes
Boot Mode Name
Censorship
BOOTCFG[1:0]
Control
0x00FF_FDE0
Serial Boot
Control
0x00FF_FDE2
Internal
Flash
State
Nexus
State
Serial
Password
Internal - Censored
00
any value except Don't care Enabled Disabled
Flash
0x55AA
Internal - Public
0x55AA
Enabled Enabled
Public
Serial - Flash Password
01
Don't care
0x55AA
Enabled Disabled
Flash
Serial - Public Password
Any value except Disabled Enabled
0x55AA
Public
Development Bus
10
separate address and
data, flash is censored
0x55AA
Don't care
Enabled Enabled
Public
Development Bus
separate address and
data, flash is NOT
censored
Any value except
0x55AA
Disabled
Development Bus
11
multiplexed address and
data, flash is censored
0x55AA
Don't care Enabled Enabled
Development Bus
multiplexed address and
data, flash is NOT
censored
Any value except
0x55AA
Disabled
The censorship word is a 32 bit word of data stored in the shadow row of internal flash memory. This
memory location is read by hardware as part of the boot process and is used in conjunction with the
BOOTCFG pins to enable and disable the internal flash memory and the Nexus interface. The censorship
word consists of two fields: censorship control and serial boot control. The censorship word is
programmed during manufacturing to be 0x55AA_55AA. This results in a device that is not censored and
uses a flash-based password for serial boot mode.
Address: 0x00FF_FDE0
Value: 0x55AA
0
Binary value 0
Hex value
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
0
1
0
1
0
1
1
0
1
0
1
0
1
0
5
5
A
A
Censorship control field–default value configures the device as uncensored.
Address: 0x00FF_FDE2
Value: 0x55AA
0
Binary value 0
Hex value
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
0
1
0
1
0
1
1
0
1
0
1
0
1
0
5
5
A
A
Serial boot control field–default value reads a password from internal flash.
Figure 9-2. Censorship Word
PXR40 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
9-5