请问各位高手：
在s12fts128kv1文档中有关于Unsecuring the Flash via the Backdoor Key Access的说明，步骤如下，如果我知道密钥该如何执行此序列，用什么方法可以写进去？用BDM 是否可以，该怎样写？谁能告诉我， 忠心感谢！
1. Set the KEYACC bit in the Flash Configuration Register FCNFG.
2. Write the correct four 16-bit words backdoor keys to Flash addresses $FF00 - $FF07 sequentially
starting with $FF00.
3. Clear the KEYACC bit.
4. If all four 16-bit words match the Flash content, the MCU is unsecured and bits SEC[1:0] in the
FSEC register are forced to the unsecure state, ‘10’.
5. If any of the four 16-bit words does not match the Flash content the MCU remains secured. | 
