HD6433044 Hitachi Semiconductor, HD6433044 Datasheet - Page 618

• Manufacturer Part Number: HD6433044
• Description: (HD64 Series) Hitachi Single-Chip Microcomputer
• Manufacturer: Hitachi Semiconductor

The error-protect state can be cleared only by a reset or entry to hardware standby mode.
Note: * It is possible to write to these registers. Note that a transition to software standby mode
The purpose of error-protect mode is to prevent overprogramming or overerasing damage to flash
memory by detecting abnormal conditions that occur if the programming or erasing algorithm is
not followed, or if a program crashes while the flash memory is being programmed or erased.
This protection function does not cover abnormal conditions other than the setting conditions of
the flash memory error bit (FLER), however. Also, if too much time elapses before the error-
protect state is reached, the flash memory may already have been damaged. This function
accordingly does not offer foolproof protection from damage to flash memory.
To prevent abnormal operations, when programming voltage (V
programming and erasing algorithms correctly, and keep microcontroller operations under
constant internal and external supervision, using the watchdog timer for example. If a transition to
error-protect mode occurs, the flash memory may contain incorrect data due to errors in
RD:
VF:
PR:
ER:
RD:
VF:
PR:
ER:
INIT.:
Figure 18-19 Flash Memory State Transitions in Modes 5, 6 and 7 (On-Chip ROM
Memory read enabled
Verify read enabled
Programming enabled
Erase enabled
Memory read disabled
Verify read disabled
Programming disabled
Erase disabled
Initialized state of registers (FLMCR, EBR1, EBR2)
P = 1 or E = 1
initializes these registers.
Program mode
or erase mode
RD VF PR ER
Error occurs
Enabled) when Programming Voltage (V
FLER = 0
RD VF PR ER
or verify mode
Memory read
FLER = 0
P = 0 and E = 0
Error-protect mode
RD VF PR ER
FLER = 1
Error occurs
(software standby)
RES = 0 or
STBY = 0
609
RES = 1 and STBY = 1
and not software standby
RES = 0 or STBY = 0
or software standby
Software
standby
Software standby
cleared
RES = 0 or
STBY = 0
PP
PP
) is applied, follow the
) is Applied
Error-protect mode
(software standby)
RD VF PR ER
FLER = 1
INIT.
RES = 0 or
STBY = 0
(hardware protect)
Reset or standby
RD VF PR ER
FLER = 0
INIT.