Specific Registers; System Wait Control Register (Vswc); Cautions - NEC UPD703116 User Manual

32-bit single-chip microcontrollers
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3.4.10 Specific registers

Specific registers are registers that are protected from being written with illegal data due to inadvertent program
loop (runaway), etc. The V850E/IA1 has three specific registers, the power save control register (PSC) (refer to 8.5.2
(13) Power save control register (PSC)), clock control register (CKC) (refer to 8.3.4 Clock control register (CKC)),
and flash programming mode control register (FLPMC) (refer to 16.7.12 Flash programming mode control register
(FLPMC)).

3.4.11 System wait control register (VSWC)

Set the value shown below to this register.
This register can be read/written in 8-bit units (address: FFFFF06EH, initial value: 77H).
Remark
If the timing of changing the flag or count value conflicts with the timing of accessing a register when a
register including a status flag that indicates the status of an on-chip peripheral function (such as ASIF0)
or a register indicating the count value of a timer (such as TM0n) is accessed, a register access retry
operation is performed. As a result, a longer time may be required to access the on-chip peripheral I/O
register.
System wait control register
(VSWC)

3.4.12 Cautions

(1) Register to be set first
When using the V850E/IA1, the following registers must be set from the beginning.
• System wait control register (VSWC)
(See 3.4.11 System wait control register (VSWC))
• Clock control register (CKC)
(See 8.3.4 Clock control register (CKC))
After setting VSWC and CKC, set other registers as required.
98
CHAPTER 3 CPU FUNCTION
Register Name
When PRM02 register = 01H
When PRM02 register = 00H
User's Manual U14492EJ5V0UD
VSWC Set Value
12H (3 clocks are set for the wait)
15H (6 clocks are set for the wait)

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