Renesas M16C/64C User Manual page 794

M16C/64C Group
32.3 Notes on Protection
After setting the PRC2 bit to 1 (write enabled), by writing to a given SFR, the PRC2 bit becomes 0 (write
disabled). Change the registers protected by the PRC2 bit in the next instruction after setting the PRC2 bit
to 1. Make sure there are no interrupts or DMA transfers between the instruction that sets the PRC2 bit to
1 and the next instruction.
R01UH0092EJ0110 Rev.1.10
Jul 31, 2012
32. Usage Notes
Page 761 of 807