Memory Map Control (S12PMMCV1)
Read: Anytime.
Write: Only if a transition is allowed (see Figure 3-4).
The MODC bit of the MODE register is used to select the MCU’s operating mode.
Table 3-5. MODE Field Descriptions
Field
Description
7
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 registered
into the respective register bit after the RESET signal goes inactive (see Figure 3-4).
Write restrictions exist to disallow transitions between certain modes. Figure 3-4 illustrates all allowed mode
changes. Attempting non authorized transitions will not change the MODE bit, but it will block further writes to
the register bit except in special modes.
MODC
Write accesses to the MODE register are blocked when the device is secured.
RESET
1
0
Special
Single-Chip
(SS)
Normal
Single-Chip
(NS)
1
0
1
Figure 3-4. Mode Transition Diagram when MCU is Unsecured
3.3.2.2
Direct Page Register (DIRECT)
Address: 0x0011
7
6
5
4
3
2
1
0
R
W
DP15
0
DP14
DP13
DP12
DP11
DP10
DP9
DP8
Reset
0
0
0
0
0
0
0
Figure 3-5. Direct Register (DIRECT)
Read: Anytime
Write: anytime in special SS, writr-one in NS.
This register determines the position of the 256 Byte direct page within the memory map.It is valid for both
global and local mapping scheme.
S12P-Family Reference Manual, Rev. 1.13
Freescale Semiconductor
111
FREESCALE [ Freescale ]
