Preliminary User’s Manual U19014EJ1V0UD
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CHAPTER 18 OPTION BYTE
18.1
Functions of Option Bytes
The flash memory at 0080H to 0084H of the
µ
PD78F0730 is an option byte area. When power is turned on or
when 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.
When the boot swap operation is used during self-programming, 0080H to 0084H are switched to 1080H to 1084H.
Therefore, set values that are the same as those of 0080H to 0084H to 1080H to 1084H in advance.
(1) 0080H/1080H
{
Internal low-speed oscillator operation
•
Can be stopped by software
•
Cannot be stopped
{
Watchdog timer interval time setting
{
Watchdog timer counter operation
•
Enabled counter operation
•
Disabled counter operation
{
Watchdog timer window open period setting
(2) 0081H/1081H
{
Selecting POC mode
•
During 2.7 V/1.59 V POC mode operation (POCMODE = 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 not detected at
2.7 V but is detected at 1.59 V (TYP.).
•
During 1.59 V POC mode operation (POCMODE = 0)
The device is in the reset state upon power application and until the supply voltage reaches 1.59 V (TYP.).
It is released from the reset state when the voltage exceeds 1.59 V (TYP.). After that, POC is detected at
1.59 V (TYP.), in the same manner as on power application.
Caution For
the
µ
PD78F0730, be sure to set POCMODE to 1.
(3) 0084H/1084H
{
On-chip debug operation control
•
Disabling on-chip debug operation
•
Enabling on-chip debug operation and erasing data of the flash memory in case authentication of the on-
chip debug security ID fails
•
Enabling on-chip debug operation and not erasing data of the flash memory even in case authentication of
the on-chip debug security ID fails
Caution To use the on-chip debug function with a product equipped with the on-chip debug function
(
µ
PD78F0730), set 02H or 03H to 0084H. Set a value that is the same as that of 0084H to 1084H
because 0084H and 1084H are switched at boot swapping.
Caution Be sure to set 00H to 0082H and 0083H (0082H/1082H and 0083H/1083H when the boot swap
function is used).
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