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8.6.3
Error Protection
In error protection, an error is detected when MCU runaway occurs during flash memory
programming/erasing, or operation is not performed in accordance with the program/erase
algorithm, and the program/erase operation is aborted. Aborting the program/erase operation
prevents damage to the flash memory due to overprogramming or overerasing.
If the MCU malfunctions during flash memory programming/erasing, the FLER bit is set to 1 in
FLMCR2 and the error protection state is entered. The FLMCR1, FLMCR2, EBR1, and EBR2
settings are retained, but program mode or erase mode is aborted at the point at which the error
occurred. Program mode or erase mode cannot be re-entered by re-setting the P1, E1, P2 or E2
bit. However, PV1, EV1, PV2 or EV2 bit setting is enabled, and a transition can be made to
verify mode.
FLER bit setting conditions are as follows:
(1) When flash memory is read during programming/erasing (including a vector read or
instruction fetch)
(2) Immediately after exception handling (excluding a reset) during programming/erasing
(3) When a SLEEP instruction is executed during programming/erasing
Error protection is released only by a reset and in hardware standby mode.
Figure 8.14 shows the flash memory state transition diagram.
: Memory read possible
: Verify-read possible
: Programming possible
: Erasing possible
RD
VF
PR
ER
: Memory read not possible
: Verify-read not possible
: Programming not possible
: Erasing not possible
RD
VF
PR
ER
RD VF PR ER FLER = 0
Error occurrence
Error occurrence
SLEEP instruction
execution
RES = 0
RES = 0
RES = 0
RD VF PR ER FLER = 0
Program mode
Erase mode
Reset
(hardware protection)
RD VF PR ER FLER = 1
RD VF PR ER FLER = 1
Error protection mode
Error protection mode
(Power-down state)
*
1
Power-down state
*
1
FLMCR1, FLMCR2 (except FLER bit), EBR1, EBR2
initialization state
FLMCR1, FLMCR2,
EBR1, EBR2 initialization
state
Power-down state
*
1
release
*
1: Watch mode, standby mode, and
subactive mode
Figure 8.14 Flash Memory State Transitions
Summary of Contents for Hitachi H8S/2191
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