MC9S12HY64 Datasheet, PDF (46/792 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Device Overview MC9S12HY/HA-Family
1.9 Modes of Operation
The MCU can operate in different modes. These are described in 1.9.1 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 1.9.2 Low Power Operation.
Some modules feature a software programmable option to freeze the module status whilst the background
debug module is active to facilitate debugging.
1.9.1 Chip Configuration Summary
The different modes and the security state of the MCU affect the debug features (enabled or disabled). The
operating mode out of reset is determined by the state of the MODC signal during reset (see Table 1-10).
The MODC bit in the MODE register shows the current operating mode and provides limited mode
switching during operation. The state of the MODC signal is latched into this bit on the rising edge of
RESET.
Table 1-10. Chip Modes
Chip Modes
Normal single chip
Special single chip
MODC
1
0
1.9.1.1 Normal Single-Chip Mode
This mode is intended for normal device operation. The opcode from the on-chip memory is being
executed after reset (requires the reset vector to be programmed correctly). The processor program is
executed from internal memory.
1.9.1.2 Special Single-Chip Mode
This mode is used for debugging single-chip operation, boot-strapping, or security related operations. The
background debug module BDM is active in this mode. The CPU executes a monitor program located in
an on-chip ROM. BDM firmware waits for additional serial commands through the BKGD pin.
1.9.2 Low Power Operation
The MC9S12HY/HA has two static low-power modes Pseudo Stop and Stop Mode. For a detailed
description refer to S12CPMU section.
1.10 Security
The MCU security mechanism prevents unauthorized access to the Flash memory. Refer to Section 5.4.1
Security and Section 17.5 Security
MC9S12HY/HA-Family Reference Manual, Rev. 1.04
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Freescale Semiconductor