96
38B7 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
PRELIMINARY
Notice: This is not a final specification.
change.
Some parametric limits are subject to
G
Program command
When
“
40
16
”
is written to the flash command register, the
M38B79FF enters the program mode.
Subsequently to this, if the instruction (for instance, STA
instruction) for writing byte data in the address to be programmed
is executed, the control circuit of the flash memory executes the
program. The erase/program busy flag of the flash memory control
register is set to
“
1
”
when the program starts, and becomes
“
0
”
when the program is completed. Accordingly, after the write in-
struction is executed, CPU can recognize the completion of the
program by polling this bit.
The programmed area must be specified beforehand by the erase/
program area select bits.
During programming, watchdog timer stops with
“
FFFF
16
”
set.
Note:
A programming operation is not completed by executing the
program command once. Always be sure to execute a pro-
gram verify command after executing the program command.
When the failure is found in this verification, the user must re-
peatedly execute the program command until the pass. Refer
to Figure 101 for the flow chart of the programming.
G
Program verify command
When
“
C0
16
”
is written to the flash command register, the
M38B79FF enters the program verify mode. Subsequently to this,
if the instruction (for instance, LDA instruction) for reading byte
data from the address to be verified (i.e., previously programmed
address), the contents which has been written to the address ac-
tually is read.
CPU compares this read data with data which has been written by
the previous program command. In consequence of the compari-
son, if not agreeing, the operation of
“
program
→
program verify
”
must be executed again.
G
Erase command
When writing
“
20
16
”
twice continuously to the flash command reg-
ister, the flash memory control circuit performs erase to the area
specified beforehand by the erase/program area select bits.
Erase/program busy flag of the flash memory control register be-
comes
“
1
”
when erase begins, and it becomes
“
0
”
when erase
completes. Accordingly, CPU can recognize the completion of
erase by polling this bit.
Data
“
00
16
”
must be written to all areas to be erased by the pro-
gram and the program verify commands before the erase
command is executed.
During erasing, watchdog timer stops with
“
FFFF
16
”
set.
Note:
The erasing operation is not completed by executing the erase
command once. Always be sure to execute an erase verify
command after executing the erase command. When the fail-
ure is found in this verification, the user must repeatedly ex-
ecute the erase command until the pass. Refer to Figure 101
for the erasing flowchart.
G
Erase verify command
When
“
A0
16
”
is written to the flash command register, the
M38B79FF enters the erase verify mode. Subsequently to this, if
the instruction (for instance, LDA instruction) for reading byte data
from the address to be verified, the contents of the address is
read.
CPU must erase and verify to all erased areas in a unit of ad-
dress.
If the address of which data is not
“
FF
16
”
(i.e., data is not erased)
is found, it is necessary to discontinue erasure verification there,
and execute the operation of
“
erase
→
erase verify
”
again.
Note:
By executing the operation of
“
erase
→
erase verify
”
again
when the memory not erased is found. It is unnecessary to
write data
“
00
16
”
before erasing in this case.
G
Reset command
The reset command is a command to discontinue the program or
erase command on the way. When
“
FF
16
”
is written to the command
register two times continuously after
“
40
16
”
or
“
20
16
”
is written to the
flash command register, the program, or erase command becomes
invalid (reset), and the M38B79FF enters the reset mode.
The contents of the memory does not change even if the reset com-
mand is executed.
DC Electric Characteristics
Note:
The characteristic concerning the flash memory part are the
same as the characteristic of the parallel I/O mode.
AC Electric Characteristics
Note:
The characteristics are the same as the characteristic of the
microcomputer mode.