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8.6
Notes on Usage
When using the EEPROM, note the following points.
(1) Write/Erase Abort: If an external reset is input during write or erase operation, the write or
erase operation in progress is aborted and the control registers are initialized. In this case, data
written to the EEPROM is not guaranteed.
(2) EEPMOV Instruction Execution with Invalid Register Settings: If registers R4L and R6
are set so as to cross a page boundary, the EEPROM write or erase operation is performed within
the page including the initial address in R6.
Example: In the H8/3153, if:
R4L = H'40
R5 = H'FF00
R6 = H'8030
Then the block data transfer is performed as follows:
RAM addresses H'FF00 to H'FF0F → EEPROM addresses H'8030 to H'803F
RAM addresses H'FF10 to H'FF3F → EEPROM addresses H'8000 to H'802F
(3) Rewrite/Overwrite Operations: Rewrite/overwrite operations can be specified in 1-byte
units, but are executed in 8-byte units depending on the address and the number of bytes to be
written into the EEPROM. Figure 8.16 shows the rewrite/overwrite operation areas (for H8/3153).
Case 1: Rewrite/overwrite to the first one byte in a page
If the rewrite/overwrite address specifies the first one byte in a page, only the first 8-byte
area is rewritten/overwritten. The remaining area in the page is not rewritten/overwritten.
Case 2: Rewrite/overwrite to the first nine bytes in a page
If the rewrite/overwrite address specifies the first nine bytes in a page, only the first 16-
byte area is rewritten/overwritten. The remaining area in the page is not
rewritten/overwritten.
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