RL78/G1H CHAPTER 26 OPTION BYTE
R01UH0575EJ0120 Rev. 1.20 Page 797 of 920
Dec 22, 2016
CHAPTER 26 OPTION BYTE
26.1 Functions of Option Bytes
Addresses 000C0H to 000C3H of the flash memory form an option byte area.
Option bytes consist of user option byte (000C0H to 000C2H) and on-chip debug option byte (000C3H).
Upon power application or resetting and starting, an option byte is automatically referenced and a specified function
is set. When using the product, be sure to set the following functions by using the option bytes.
For the bits to which no function is allocated, do not change their initial values.
To use the boot swap operation during self-programming, 000C0H to 000C3H are replaced by 010C0H to 010C3H.
Therefore, set the same values as 000C0H to 000C3H to 010C0H to 010C3H.
Remark The option bytes should always be set regardless of whether each function is used.
26.1.1 User option byte (000C0H to 000C2H/010C0H to 010C2H)
(1) 000C0H/010C0H
Setting of watchdog timer operation
• Enabling or disabling of counter operation
• Enabling or disabling of counter operation in the HALT or STOP mode
Setting of interval time of watchdog timer
Setting of window open period of watchdog timer
Setting of interval interrupt of watchdog timer
• Interval interrupt is used or not used
Caution Set the same value as 000C0H to 010C0H when the boot swap operation is used because
000C0H is replaced by 010C0H.
(2) 000C1H/010C1H
Setting of LVD operation mode
• Interrupt & reset mode
• Reset mode
• Interrupt mode
• LVD off (external reset input from the RESET
pin is used)
Setting of LVD detection level (V
LVDH, VLVDL, VLVD)
Caution 1. After power is supplied, the reset state must be retained until the operating voltage becomes
in the range defined in 31.4 AC Characteristics. This is done by utilizing the voltage detection
circuit or controlling the externally input reset signal. After the power supply is turned off, this
LSI should be placed in the STOP mode, or placed in the reset state by utilizing the voltage
detection circuit or controlling the externally input reset signal, before the voltage falls below
the operating range. The range of operating voltage varies with the setting of the user option
byte (000C2H or 010C2H).
Caution 2. Set the same value as 000C1H to 010C1H when the boot swap operation is used because
000C1H is replaced by 010C1H.
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