MC9S12UF32PB Freescale Semiconductor, MC9S12UF32PB Datasheet - Page 83

• Manufacturer Part Number: MC9S12UF32PB
• Description: IC MCU 32K FLASH 30MHZ 64LQFP
• Manufacturer: Freescale Semiconductor
• Series: HCS12r

Specifications of MC9S12UF32PB

• Core Processor: HCS12
• Core Size: 16-Bit
• Speed: 30MHz
• Connectivity: ATA, Compact Flash, EBI/EMI, Memory Stick, MMC, SCI, SD, Smart Media, USB
• Peripherals: POR, WDT
• Number Of I /o: 41
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Ram Size: 3.5K x 8
• Voltage - Supply (vcc/vdd): 2.25 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

The user must be reminded that part of the security must lie with the user’s code. An extreme example
would be user’s code that dumps the contents of the internal program. This code would defeat the purpose
of security. At the same time the user may also wish to put a back door in the user’s program. An example
of this is the user downloads a key through the SCI which allows access to a programming routine that
updates parameters stored in FLASH. Please refer to the HCS12 Core User Guide for more information
about security.
4.4.1 Securing the Microcontroller
Once the user has programmed the FLASH, the part can be secured by programming the security bits
located in the FLASH module. These non-volatile bits will keep the part secured through resetting the part
and through powering down the part.
The security byte resides in a portion of the Flash array.
Check the Flash Block Guide for more details on the security configuration.
4.4.2 Operation of the Secured Microcontroller
4.4.2.1 Normal Single Chip Mode
This will be the most common usage of the secured part. Everything will appear the same as if the part was
not secured with the exception of BDM operation. The BDM operation will be blocked.
4.4.2.2 Executing from External Memory
The user may wish to execute from external space with a secured microcontroller. This is accomplished
by resetting directly into expanded mode. The internal FLASH will be disabled. BDM operations will be
blocked.
4.4.3 Unsecuring the Microcontroller
There are two methods for unsecuring the Microcontroller. If the contents of the flash are known then the
microcontroller can be unsecured using the backdoor key access feature. The other unsecuring method is
to fully erase the FLASH.
4.4.3.1 Unsecuring the Microcontroller (backdoor key access)
In normal modes, either SINGLE CHIP or EXPANDED, the microcontroller may only be unsecured by
using the backdoor key access feature. This requires knowledge of the contents of the backdoor keys,
which must be written to the Flash memory space at the appropriate addresses, in the correct order. In
addition, in SINGLE CHIP mode the user code stored in the Flash must have a method of receiving the
backdoor key from an external stimulus. This external stimulus would typically be through one of the
Freescale Semiconductor
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Protection of the contents of FLASH,
Operation in single-chip mode,
Operation from external memory with internal FLASH disabled.
System on a Chip Guide — 9S12UF32DGV1/D V01.05
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