MC9S12XF512_1 Datasheet, PDF (68/1306 Pages) Freescale Semiconductor, Inc – S12X Microcontrollers

Chapter 1 MC9S12XF-Family Reference Manual
1.4 Modes of Operation
The MCU can operate in different modes associated with MCU resource mapping and bus interface
configuration. These are described in 1.4.1 Chip Configuration Summary.
The MCU can operate in different power modes to facilitate power saving when full system performance
is not required. These are described in 1.4.2 Power Modes.
Some modules feature a software programmable option to freeze the module status whilst the background
debug module is active to facilitate debugging. This is described in 1.4.3 Freeze Mode.
The “system state” for the XCPU is always Supervisor State (see Chapter 17 Memory Protection Unit
(S12XMPUV2)).
1.4.1 Chip Configuration Summary
The MCU can operate in six different modes associated with resource configuration. The different modes,
the state of ROMCTL and EROMCTL signal on rising edge of RESET and the security state of the MCU
affect the following device characteristics:
• External bus interface configuration
• Flash in memory map, or not
• Debug features enabled or disabled
The operating mode out of reset is determined by the states of the MODC, MODB, and MODA signals
during reset (see Table 1-12 ). The MODC, MODB, and MODA bits in the MODE register show the
current operating mode and provide limited mode switching during operation. The states of the MODC,
MODB, and MODA signals are latched into these bits on the rising edge of RESET.
In normal expanded mode and in emulation modes the ROMON and the EROMON bits in the MISC
register defines if the on chip flash memory is the memory map, or not. (See Table 1-12 .) For a detailed
explanation of the ROMON and EROMON bits refer to the MMC description.
The state of the ROMCTL signal is latched into the ROMON bit in the MMCCTL1 register on the rising
edge of RESET. The state of the EROMCTL signal is latched into the EROMON bit in the MMCCTL1
register on the rising edge of RESET.
MC9S12XF - Family Reference Manual, Rev.1.19
68
Freescale Semiconductor