upd70f3017ay Renesas Electronics Corporation., upd70f3017ay Datasheet - Page 88

• Manufacturer Part Number: upd70f3017ay
• Description: V850/sa1tm 32-/16-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

(1) Command register (PRCMD)
After reset: Undefined
(2) System status register (SYS)
After reset: 00H
88
PRCMD
Symbol
Symbol
SYS
The command register (PRCMD) is a register used when write-accessing a specific register to prevent incorrect
writing to the specific register due to the erroneous program execution.
This register can be written in 8-bit units. It becomes undefined in a read cycle.
Occurrence of illegal write operations can be checked by the PRERR bit of the SYS register.
This register is allocated with status flags showing the operating state of the entire system. This register can be
read/written in 8-bit or 1-bit units.
The operating conditions of PRERR flag are shown below.
(a) Set conditions (PRERR = 1)
(b) Reset conditions (PRERR = 0)
Remark n = 0 to 7
(1) When a write operation to the specific register took place in a state where the store instruction operation
(2) When the first store instruction operation following a write operation to the PRCMD register is to any
(1) When 0 is written to the PRERR flag of the SYS register
(2) At system reset
Note If 0 is written to the PRERR flag immediately after writing to the PRCMD register, the PRERR flag is
PRERR
REG7
REGn
for the recent peripheral I/O was not a write operation to the PRCMD register
peripheral I/O register (including the PRCMD register and SYS register) apart from specific registers
0/1
7
7
0
0
1
set to 1 (because the SYS register is not a specific register).
R/W
Any 8-bit data
Protection error did not occur
Protection error occurred
REG6
W
6
6
0
REG5
5
5
0
CHAPTER 3 CPU FUNCTIONS
PRERR
REG4
User’s Manual U12768EJ4V1UD
Address: FFFFF170H
Address: FFFFF078H
Detection of Protection Error
4
4
Registration Code
REG3
3
3
0
REG2
Note
2
2
0
REG1
1
1
0
REG0
0
0
0