SNIU028D February 2016 – September 2020 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
The process for writing to Program Flash is exactly the same as the process for writing to Data Flash – write the key, write to the actual address, and then monitor the BUSY bit. Like Data flash, Program flash should be written to 4 bytes at a time. Program flash can be written to twice between erases. This is used in the clear checksum function, where first the checksum is written, and then all zeroes are written to the checksum to clear it. Writing to the flash more than twice between erases is not guaranteed to work and hence not recommended.