UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 802

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

25.1 Functions of Option Bytes
the device is restarted from the reset status, the device automatically references the option bytes and sets specified
functions. When using the product, be sure to set the following functions by using the option bytes.
Therefore, set values that are the same as those of 0080H to 0084H to 1080H to 1084H in advance.
(1) 0080H/1080H
(2) 0081H/1081H
800
The flash memory at 0080H to 0084H of the 78K0/Dx2 is an option byte area. When power is turned on or when
When the boot swap operation is used during self-programming, 0080H to 0084H are switched to 1080H to 1084H.
Caution Be sure to set 00H to 0082H and 0083H (0082H/1082H and 0083H/1083H when the boot swap
Internal low-speed oscillator operation
Watchdog timer interval time setting
Watchdog timer counter operation
Watchdog timer window open period setting
Caution Set a value that is the same as that of 0080H to 1080H because 0080H and 1080H are
Selecting POC mode
Caution LVISTART can only be written by using a dedicated flash memory programmer. It cannot be
Can be stopped by software
Cannot be stopped
Enabled counter operation
Disabled counter operation
During 2.7 V POC mode operation (LVISTART = 1)
The device is in the reset state upon power application and until the supply voltage reaches 2.7 V (TYP.). It
is released from the reset state when the voltage exceeds 2.7 V (TYP.). After that, POC is detected at 2.7 V
(TYP.), in the same manner as on power application.
During LVI operation stop mode (LVISTART = 0)
The LVI operation stops.
function is used).
switched during the boot swap operation.
set during self-programming or boot swap operation during self-programming (at this time,
LVI operation stop mode (default) is set). However, because the value of 1081H is copied to
0081H during the boot swap operation, it is recommended to set a value that is the same as
that of 0081H to 1081H when the boot swap function is used.
CHAPTER 25 OPTION BYTE
Preliminary User’s Manual U19748EJ1V0UD