MCF51EM256CLL Freescale Semiconductor, MCF51EM256CLL Datasheet - Page 106

• Manufacturer Part Number: MCF51EM256CLL
• Description: IC MCU 32BIT 256KB FLASH 100LQFP
• Manufacturer: Freescale Semiconductor
• Series: MCF51EMr

Specifications of MCF51EM256CLL

• Core Processor: Coldfire V1
• Core Size: 32-Bit
• Speed: 50MHz
• Connectivity: I²C, SCI, SPI
• Peripherals: LCD, LVD, PWM, WDT
• Number Of I /o: 63
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 16x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LQFP
• Processor Series: MCF51EM
• Core: ColdFire V1
• Data Bus Width: 32 bit
• Data Ram Size: 16 KB
• Interface Type: RS-232, LIN
• Maximum Clock Frequency: 50 MHz
• Number Of Timers: 3
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Development Tools By Supplier: DEMOEM
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Memory
The backdoor key access sequence is monitored by an internal security state machine. An illegal operation
during the backdoor key access sequence causes the security state machine to lock, leaving the MCU in
the secured state. A reset of the MCU causes the security state machine to exit the lock state and allows a
new backdoor key access sequence to be attempted. The following operations during the backdoor key
access sequence lock the security state machine:
After the backdoor keys have been correctly matched, the MCU is unsecured. After the MCU is unsecured,
the flash security byte can be programmed to the unsecure state, if desired.
In the unsecure state, you have full control of the contents of the backdoor keys by programming the
associated addresses in the flash configuration field (see
Locations”).
The security as defined in the flash security byte is not changed by using the backdoor key access sequence
to unsecure. The stored backdoor keys are unaffected by the backdoor key access sequence. After the next
reset of the MCU, the security state of the flash module is determined by the flash security byte. The
backdoor key access sequence has no effect on the program and erase protections defined in the flash
protection register (FxPROT).
It is not possible to unsecure the MCU by using the backdoor key access sequence in background debug
mode (BDM) because the MCU does not allow flash array writes in BDM to the flash module.
3-50
5. If all data written match the backdoor keys, the MCU is unsecured and the SEC[1:0] bits in the
1. If any of the keys written does not match the backdoor keys programmed in the flash array.
2. If the keys are written in the wrong sequence.
3. If any of the keys written are all 0’s or all 1’s.
4. If the KEYACC bit does not remain set while the keys are written.
5. If any of the keys are written on successive MCU clock cycles.
6. Executing a STOP instruction before all keys have been written.
NVOPT register are forced to an unsecured state.
MCF51EM256 Series ColdFire Integrated Microcontroller Reference Manual, Rev. 8
Section 3.6, “Flash Module Reserved Memory
Freescale Semiconductor