CHAPTER 3 CPU FUNCTION
Preliminary User’s Manual U15905EJ1V0UD
91
The PRERR flag operates under the following conditions.
(a) Set condition (PRERR = 1)
(i) When data is written to a special register without writing anything to the PRCMD register (when <4> is
executed without executing <3> in
3.4.8 (1) Setting special register
)
(ii) When data is written to a peripheral I/O register other than a special register (including execution of a
bit manipulation instruction) after writing data to the PRCMD register (if <4> in
3.4.8 (1) Setting
special register
is not the setting of a special register)
Remark
Even if a peripheral I/O register is read (including execution of a bit manipulation instruction)
between a write access to the PRCMD register and a write access to a special register other
than the WDTM register (PCC, PSC, and BPS registers) (such as an access to the internal
RAM), the PRERR flag is not set and data can be written to the special register.
(b) Clear condition (PRERR = 0)
(i) When 0 is written to the PRERR flag of the SYS register
(ii) When the system is reset
Cautions 1. If 0 is written to the PRERR bit of the SYS register, which is not a special register,
immediately after a write access to the PRCMD register, the PRERR bit is cleared to 0 (the
write access takes precedence).
2. If data is written to the PRCMD register, which is not a special register, immediately after a
write access to the PRCMD register, the PRERR bit is set to 1.
Содержание V850ES/SA2 UPD703201
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