Datasheet

Memory Mapping Control (S12XMMCV4)
S12XS Family Reference Manual, Rev. 1.13
132 Freescale Semiconductor
3.3.2.1 Mode Register (MODE)
Read: Anytime. Write: Only if a transition is allowed (see Figure 3-5).
The MODE bits of the MODE register are used to establish the MCU operating mode.
Figure 3-4.
Figure 3-5. Mode Transition Diagram when MCU is Unsecured
Address: 0x000B PRR
76543210
R
MODC
0000000
W
Reset MODC
1
0000000
1. External signal (see Table 3-2).
= Unimplemented or Reserved
Figure 3-3. Mode Register (MODE)
Table 3-3. MODE Field Descriptions
Field Description
7
MODC
Mode Select Bit — This bit controls the current operating mode during
RESET high (inactive). The external
mode pin MODC determines the operating mode during
RESET low (active). The state of the pin is latched into
the respective register bit after the
RESET signal goes inactive (see Figure 3-3).
Write restrictions exist to disallow transitions between certain modes. Figure 3-5 illustrates all allowed mode
changes. Attempting non authorized transitions will not change the MODE bits, but it will block further writes to
these register bits except in special modes.
Write accesses to the MODE register are blocked when the device is secured.
Normal
Single-Chip
1
Special
Single-Chip
0
RESET
(SS)
0
RESET
1
(NS)
RESET
Transition done by external pins (MODC)
Transition done by write access to the MODE register
1
State
State
State