S912XEP768J5MAGR Freescale Semiconductor, S912XEP768J5MAGR Datasheet - Page 349

• Manufacturer Part Number: S912XEP768J5MAGR
• Description: 16-bit Microcontrollers - MCU 16-bit 768K Flash
• Manufacturer: Freescale Semiconductor

Specifications of S912XEP768J5MAGR

• Rohs: yes
• Core: HCS12X
• Processor Series: MC9S12
• Data Bus Width: 16 bit
• Maximum Clock Frequency: 50 MHz
• Program Memory Size: 768 KB
• Data Ram Size: 48 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 3.3 V to 5 V
• Operating Temperature Range: - 40 C to + 125 C
• Package / Case: LQFP-144
• Mounting Style: SMD/SMT

The meaning of the security bits SEC[1:0] is shown in
security is controlled by two bits. To put the device in unsecured mode, these bits must be programmed to
SEC[1:0] = ‘10’. All other combinations put the device in a secured mode. The recommended value to put
the device in secured state is the inverse of the unsecured state, i.e. SEC[1:0] = ‘01’.
9.1.4
By securing the device, unauthorized access to the EEPROM and Flash memory contents can be prevented.
However, it must be understood that the security of the EEPROM and Flash memory contents also depends
on the design of the application program. For example, if the application has the capability of downloading
code through a serial port and then executing that code (e.g. an application containing bootloader code),
then this capability could potentially be used to read the EEPROM and Flash memory contents even when
the microcontroller is in the secure state. In this example, the security of the application could be enhanced
by requiring a challenge/response authentication before any code can be downloaded.
Secured operation has the following effects on the microcontroller:
9.1.4.1
Freescale Semiconductor
•
•
•
•
Background debug module (BDM) operation is completely disabled.
Execution of Flash and EEPROM commands is restricted. Please refer to the NVM block guide for
details.
Tracing code execution using the DBG module is disabled.
Debugging XGATE code (breakpoints, single-stepping) is disabled.
Operation of the Secured Microcontroller
Normal Single Chip Mode (NS)
Please refer to the Flash block guide for actual security configuration (in
section “Flash Module Security”).
KEYEN[1:0]
Table 9-3. Backdoor Key Access Enable Bits
SEC[1:0]
MC9S12XE-Family Reference Manual Rev. 1.25
00
01
10
11
00
01
10
11
Table 9-4. Security Bits
NOTE
Table
Access Enabled
Security State
0 (unsecured)
Backdoor Key
1 (secured)
1 (secured)
1 (secured)
0 (disabled)
0 (disabled)
0 (disabled)
9-4. For security reasons, the state of device
1 (enabled)
Chapter 9 Security (S12XE9SECV2)
349