One Time Programmable  functionality  in PSoC 3/5

Question: Is it possible to implement OTP (one time programmable) functionality in PSoC 3/5 such that Flash content can never be altered after it is programmed?

 

Answer:

The Full Protection setting for Flash memory, along with the device security feature can prevent the Flash from ever being modified. This combination is the highest level of security setting available in PSoC 3/5 devices. The steps to do this are given below:

1. Erase the entire Flash memory using the Erase All command

2. Reprogram the Flash content.

3. Write a 32-bit key (0x50536F43) into the WO latch to enable device security.

4. Set Flash Protection setting to Full Protection.

5. Reset the part to lock it.