R01US0068EJ0100 Datasheet, PDF (14/56 Pages) Renesas Technology Corp – EEPROM Emulation Library

RL78 Family
EEPROM Emulation Library Pack02
Chapter 2 EEPROM Emulation
Between reference area and data area, there is an erased area. With each EEL data update (i.e. the data is
written), this area is reduced successively. However, at least two bytes of space always remain between reference
area and data area for management and separation of these areas. This is indicated by the separator in Figure 2-4.
The EEL block header is detailed in 2.3.4, EEL Block Header, while the structure of data stored in the reference
and data area are described in Section 2.3.5, Structure of Stored Data.
2. 3. 4 EEL Block Header
The structure of the block header is depicted in Figure 2-5. It is composed of eight bytes, four of which are
reserved for the system.
Figure 2-5 Structure of EEL block header
relative byte
index within
block
0x0000 A
0x0001 B
0x0002 I
0x0003 X
0x0004 -
0x0005 -
0x0006 -
0x0007 -
N
0xFF -　N
0x00
0x00
Reserved
Reserved
Reserved
Reserved
The block status flags start at the beginning of the block and include the A flag, B flag, I flag, and X flag, each of
which is one byte, for a total of 4 bytes of data. The combination of flags indicates the EEL block status.
Figure 2-5 shows the placement status of flags, and Table 2-3 shows the combination status of flags.
Table 2-3 Overviews of Block Status Flags
Block Status Flag
A Flag B Flag I Flag X Flag
0x01 0xFE 0xFF 0xFF
0x02 0xFD 0xFF 0xFF
0x03 0xFC 0xFF 0xFF
Data other than
the above
--
0xFF
other
than
0xFF
--
--
0xFF
0xFF
other
than
0xFF
State
Description
Active
Currently used block
After the EEL_CMD_REFRESH command is executed,
the A flag of a new active block is set to 0x02.
Currently used block
After the EEL_CMD_REFRESH command is executed,
the A flag of a new active block is set to 0x03.
Currently used block
After the EEL_CMD_REFRESH command is executed,
the A flag of a new active block is set to 0x01.
Invalid Invalid block
Excluded Excluded block
R01US0068EJ0100 Rev.1.00
Mar. 28, 2014
Page 14 of 53