Bit 7—Programming Power (V
PP
): Programming power bit (V
PP
) detects V
PP
, and level is
displayed as “1” or “0.” The permissible output currents for impressed high voltage VH are given
in 21.3.1, “DC Characteristics.” The value of VH ranges from V
CC
+ 2 V to 11.4 V. If a voltage in
excess of VH is applied, “1” is displayed; otherwise “0” is displayed.
This bit restricts the hardware protect functions during write and erase operations for the flash
memory. For details on hardware protect, see 18.7.8, “Protect Modes.” For notes on VPP usage,
see 10.10, “Flash Memory Programming and Erasing Precautions.”
Bit 7
V
PP
Description
0
[Clear conditions]
(Initial value)
This is the regular operational mode when a voltage exceeding
VH is not applied to the V
PP
pin. The flash memory cannot be
written or erased. “Hardware Protect” is displayed.
1
[Set conditions]
This is the operational mode when a voltage exceeding VH is
applied to the V
PP
pin. The flash memory can be written and
erased. “Hardware Protect Disabled” is displayed
*
.
Note:
For correct write and erase functions, the setting should be V
PP
= 12.0 V to 0.6 V (11.4 V to
12.6 V).
Bit 6—V
PP
Enable (V
PP
E): Disables or enables 12-V application to the V
PP
pin. After this bit is
set, it is necessary to wait for at least 5 µs for the internal power supply to stabilize; programming
and erasing cannot be performed until stabilization is complete. After this bit is cleared, it is
necessary to wait for the flash memory read setup time (t
FRS
) in order to read flash memory.
Bit 6
V
PP
E
Description
0
V
PP
pin 12-V power supply is disabled
(Initial value)
1
V
PP
pin 12-V supply is enabled
Note: The power supply system used for the flash memory is switched by means of the VppE bit.
After switching, operation is not guaranteed during the period before the power supply
system stabilizes. It is therefore prohibited to fetch from flash memory and execute an
instruction that sets or resets the VppE bit.
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