3.10.11.2 Filling the Temporary Buffer (Page Loading)

To write an instruction word, set up the address in the Z pointer and data in R1:R0, write “00000001” to SPMCSR and execute SPM within four clock cycles after writing SPMCSR. The content of PCWORD in the Z register is used to address the data in the temporary buffer. The temporary buffer auto-erases after a page write. It is also erased after a system reset. Note that it is not possible to write more than once to each address without erasing the temporary buffer.

If the EEPROM is written in the middle of an SPM page load operation, all data loaded are lost.