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64 KByte Flash Module (S12FTMRG64K4KV2)
MC9S12VRP Family Reference Manual Rev. 1.3
486
NXP Semiconductors
If the KEYEN[1:0] bits are in the enabled state (see
), the MCU can be unsecured by the
backdoor key access sequence described below:
1. Follow the command sequence for the Verify Backdoor Access Key command as explained in
2. If the Verify Backdoor Access Key command is successful, the MCU is unsecured and the
SEC[1:0] bits in the FSEC register are forced to the unsecure state of 10
The Verify Backdoor Access Key command is monitored by the Memory Controller and an illegal key will
prohibit future use of the Verify Backdoor Access Key command. A reset of the MCU is the only method
to re-enable the Verify Backdoor Access Key command. The security as defined in the Flash security byte
(0x3_FF0F) is not changed by using the Verify Backdoor Access Key command sequence. The backdoor
keys stored in addresses 0x3_FF00-0x3_FF07 are unaffected by the Verify Backdoor Access Key
command sequence. The Verify Backdoor Access Key command sequence has no effect on the program
and erase protections defined in the Flash protection register, FPROT.
After the backdoor keys have been correctly matched, the MCU will be unsecured. After the MCU is
unsecured, the sector containing the Flash security byte can be erased and the Flash security byte can be
reprogrammed to the unsecure state, if desired. In the unsecure state, the user has full control of the
contents of the backdoor keys by programming addresses 0x3_FF00-0x3_FF07 in the Flash configuration
field.
18.5.2
Unsecuring the MCU in Special Single Chip Mode using BDM
A secured MCU can be unsecured in Special Single Chip mode by using the following method to erase the
P-Flash and D-Flash memory:
1. Reset the MCU into Special Single Chip mode
2. Delay while the BDM executes the Erase Verify All Blocks command write sequence to check if
the P-Flash and D-Flash memories are erased
3. Send BDM commands to disable protection in the P-Flash and D-Flash memory
4. Execute the Erase All Blocks command write sequence to erase the P-Flash and D-Flash memory.
Alternatively the Unsecure Flash command can be executed, if so the steps 5 and 6 below are
skipped.
5. After the CCIF flag sets to indicate that the Erase All Blocks operation has completed, reset the
MCU into Special Single Chip mode
6. Delay while the BDM executes the Erase Verify All Blocks command write sequence to verify that
the P-Flash and D-Flash memory are erased
If the P-Flash and D-Flash memory are verified as erased, the MCU will be unsecured. All BDM
commands will now be enabled and the Flash security byte may be programmed to the unsecure state by
continuing with the following steps:
7. Send BDM commands to execute the Program P-Flash command write sequence to program the
Flash security byte to the unsecured state
8. Reset the MCU
Summary of Contents for MC9S12VRP64
Page 16: ...MC9S12VRP Family Reference Manual Rev 1 3 16 NXP Semiconductors ...
Page 46: ...Device Overview S12VRP Series MC9S12VRP Family Reference Manual Rev 1 3 46 NXP Semiconductors ...
Page 236: ...S12S Debug Module S12DBGV2 MC9S12VRP Family Reference Manual Rev 1 3 236 NXP Semiconductors ...
Page 244: ...Interrupt Module S12SINTV1 MC9S12VRP Family Reference Manual Rev 1 3 244 NXP Semiconductors ...
Page 358: ...Timer Module TIM16B2CV3 MC9S12VRP Family Reference Manual Rev 1 3 358 NXP Semiconductors ...
Page 436: ...Supply Voltage Sensor BATSV2 MC9S12VRP Family Reference Manual Rev 1 3 436 NXP Semiconductors ...
Page 528: ...NVM Electrical Parameters MC9S12VRP Family Reference Manual Rev 1 3 528 NXP Semiconductors ...
Page 530: ...Package Information MC9S12VRP Family Reference Manual Rev 1 3 530 NXP Semiconductors ...
Page 531: ...Package Information MC9S12VRP Family Reference Manual Rev 1 3 NXP Semiconductors 531 ...
Page 532: ...Package Information MC9S12VRP Family Reference Manual Rev 1 3 532 NXP Semiconductors ...