M30218 Datasheet, PDF (160/179 Pages) Mitsubishi Electric Semiconductor – M30218 Group

CPU Rewrite Mode
Mitsubishi microcomputers
M30218 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Program-verify command (C016)
The program-verify mode is entered by writing the command code “C016” to the flash command
register in the first bus cycle. When the user execute an instruction (e.g., LDE instruction) to read byte
data from the address to be verified (the previously programmed address) in the second bus cycle,
the content that has actually been written to the address is read out from the memory.
The CPU compares this read data with the data that it previously wrote to the address using the
program command. If the compared data do not match, the user need to execute the program and
program-verify operations one more time.
Erase command (2016 + 2016)
The flash memory control circuit executes an erase operation by writing command code “2016” to the
flash command register in the first bus cycle and the same command code to the flash command
register again in the second bus cycle. The erase operation requires approximately 20 ms. Wait for 20
ms or more before the user go to the next processing.
Before this erase command can be performed, all memory locations to be erased must have had data
“0016” written to by using the program and program-verify commands. During erase operation, the
watchdog timer remains idle, with the value “7FFF16 set in it.
Note 1: The erase operation is not completed immediately by writing an erase command once. The
user must always execute an erase-verify command after each erase command executed. And if
verification fails, the user need to execute the erase command repeatedly until the verification passes.
See Figure BB-3 for an example of an erase flowchart.
Erase-verify command (A016)
The erase-verify mode is entered by writing the command code “A016” to the flash command register
in the first bus cycle. When the user execute an instruction to read byte data from the address to be
verified (e.g., LDE instruction) in the second bus cycle, the content of the address is read out.
The CPU must sequentially erase-verify memory contents one address at a time, over the entire area
erased. If any address is encountered whose content is not “FF16” (not erased), the CPU must stop
erase-verify at that point and execute erase and erase-verify operations one more time.
Note 1: If any unerased memory location is encountered during erase-verify operation, be sure to
execute erase and erase-verify operations one more time. In this case, however, the user does not
need to write data “0016” to memory before erasing.
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