491
(4) Set H'FF as the PROM programmer buffer data for addresses H'F780 to H'1FFFF.
The
H8/3437F PROM size is 60 kbytes. Addresses H'F780 to H'1FFFF always read H'FF, so if H'FF is
not specified as programmer data, a verify error will occur.
(5) Notes on applying, releasing, and shutting off the programming voltage (V
PP
)
Note:
In this section, the application, release, and shutting-off of V
PP
are defined as follows.
Application: A rise in voltage from V
CC
to 12 V ± 0.6 V.
Release:
A drop in voltage from 12 V ± 0.6 V to V
CC
.
Shut-off:
No applied voltage (floating).
Apply the programming voltage (V
PP
) after the rise of V
CC
, and release V
PP
before shutting off
V
CC
.
To prevent unintended programming or erasing of flash memory, in these power-on and
power-off timings, the application, release, and shutting-off of V
PP
must take place when the
microcontroller is in a stable operating condition as defined below.
Stable operating condition
The V
CC
voltage must be stabilized within the rated voltage range (V
CC
= 2.7 V to 5.5 V)*
If V
PP
is applied, released, or shut off while the microcontroller’s V
CC
voltage is not within
the rated voltage range (V
CC
= 2.7 to 5.5 V)*, since microcontroller operation is unstable,
the flash memory may be programmed or erased by mistake. This can occur even if V
CC
=
0 V. To prevent changes in the V
CC
power supply when V
PP
is applied, be sure that the
power supply is adequately decoupled with inserting bypass capacitors.
Note:
* In the LH version, V
CC
= 3.0 V to 5.5 V.
Clock oscillation must be stabilized (the oscillation settling time must have elapsed), and
oscillation must not be stopped
When turning on V
CC
power, hold the
RES
pin low during the oscillation settling time
(t
OSC1
= 20 ms), and do not apply V
PP
until after this time.
The microcontroller must be in the reset state, or in a state in which a reset has ended
normally (reset has been released) and flash memory is not being accessed
Apply or release V
PP
either in the reset state, or when the CPU is not accessing flash
memory (when a program in on-chip RAM or external memory is executing). Flash
memory cannot be read normally at the instant when V
PP
is applied or released. Do not read
flash memory while V
PP
is being applied or released.
For a reset during operation, apply or release V
PP
only after the
RES
pin has been held low
for at least ten system clock cycles (10).