MCIMX27 Datasheet, PDF (188/1650 Pages) Freescale Semiconductor, Inc – Multimedia Applications Processor

System Control
0x1002_7874 (PPCR)
Access: User read/write
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R0
0
W
0
0
PUS1 PUE1 DSE1
OE1
PUS0 PUE0 DSE0
OE0
Reset 0
0
0
1
0
0
0
0
0
0
0
1
0
0
1
1
Figure 4-26. PMIC Pad Control Register (PPCR)
Table 4-27. PMIC Pad Control Register Field Description
Field
31–14
13–12
PUS1
11
PUE1
10–9
DSE1
8
OE1
7–16
5–4
PUS0
3
PUE0
2–1
DSE0
0
OE0
Description
Reserved. These bits are reserved and should read 0.
PUS1. PUS control of BOOT1 pad. Only used when RVEN bit is set.
PUE1. PUE control of BOOT1 pad. Only used when RVEN bit is set.
DSE1. DSE control of BOOT1 pad. Only used when RVEN bit is set.
OE1. OE control of BOOT1 pad. Only used when RVEN bit is set.
Reserved. These bits are reserved and should read 0.
PUS0. PUS control of BOOT0 pad. Only used when RVEN bit is set.
PUE0. PUE control of BOOT0 pad. Only used when RVEN bit is set.
DSE0. DSE control of BOOT0 pad. Only used when RVEN bit is set.
OE0. OE control of BOOT0 pad. Only used when RVEN bit is set.
4.3 System Boot Mode Selection
The operational system boot mode of the i.MX27 processor upon system reset is determined by the
configuration of the four external input pins, BOOT[3:0]. The settings of these pins control where the
system is boot from and the memory port size.
The i.MX27 processor always begins fetching instruction from the address 0x00000000 after reset. The
BOOT[3:0] pins control the memory region that is mapped to the address 0x0. Upon power up, if the
BOOT_INT is 1, the Boot Address will always be 0x00000000. If the fuse of the BOOT_INT is blown,
the BOOT Address will be generated based on the BOOT[3:0] information. The boot modes are defined
in Table 4-28. These boot modes information are registered during the system reset. When an external chip
4-46
MCIMX27 Multimedia Applications Processor Reference Manual, Rev. 0.2
Freescale Semiconductor