Fujitsu FR81S User Manual
CHAPTER 3: CPU
10. Memory Protection Function (MPU)
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : CPU
FUJITSU SEMICONDUCTOR CONFIDENTIAL
51
10.4.6.
DEAR and DESR Update
The DEAR and the DESR update are shown.
The data access error address register (DEAR) and the data access error status register (DESR) are renewed
in the following cases.
⋅
System register access in user mode (illegal instruction exception)
⋅
Bus error in buffer prohibition area access (illegal instruction exception)
⋅
Bus error in buffer permission area access (data access error interrupt)
DEAR and DESR are renewed in the instruction that did the corresponding access and it is renewed to the
asynchronization with the instruction operation in the case where the data access error interrupt is generated
in the case where the illegal instruction exception is generated. It gives priority to the illegal instruction
exception factor when the factor is generated at the same time.
MB91520 Series
MN705-00010-1v0-E
148