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RL78/G1A CHAPTER 24 OPTION BYTE
CHAPTER 24 OPTION BYTE
24.1 Functions of Option Bytes
Addresses 000C0H to 000C3H of the flash memory of the RL78/G1A 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.
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.
24.1.1 User option byte (000C0H to 000C2H/010C0H to 010C2H)
<R>
(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 overflow time of watchdog timer
{ Setting of window open period of watchdog timer
{ Setting of interval interrupt of watchdog timer
• Whether or not to use the interval interrupt is selectable.
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 (by controlling the externally input reset signal on the RESET pin)
<R>
{ Setting of LVD detection level (V
LVDH, VLVDL, VLVD)
Cautions 1. After power is supplied, the reset state must be retained until the operating voltage becomes in
the range defined in 29.4 or 30.4 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).
2. Set the same value as 000C1H to 010C1H when the boot swap operation is used because 000C1H
is replaced by 010C1H.
R01UH0305EJ0200 Rev.2.00 792
Jul 04, 2013