R8C/20 Group, R8C/21 Group 19. Flash Memory
Rev.2.00 Aug 27, 2008 Page 375 of 458
REJ09B0250-0200
19. Flash Memory
19.1 Overview
In the flash memory version, rewrite operations to the flash memory can be performed in three modes; CPU
rewrite, standard serial I/O, parallel I/O modes.
Table 19.1 lists the Flash Memory Performance (see Table 1.1 and Table 1.2 Performance for the items not listed
on Table 19.1).
NOTES:
1. Definition of programming and erasure endurance
The programming and erasure endurance is defined on a per-block basis.
If the programming and erasure endurance is n (n = 100 or 10,000), each block can be erased n
times. For example, if 1,024 1-byte writes are performed to different addresses in block A, a 1-Kbyte
block, and then the block is erased, the programming/erasure endurance still stands at one. When
performing 100 or more rewrites, the actual erasure endurance can be reduced by executing
programming operations in such a way that all blank areas are used before performing an erase
operation. Avoid rewriting only particular blocks and try to average out the programming and erasure
endurance of the blocks. It is also advisable to retain data on the erasure endurance of each block
and limit the number of erase operations to a certain number.
2. Blocks A and B are embedded only in the R8C/21 Group.
Table 19.1 Flash Memory Performance
Item Specification
Flash Memory Operating Mode 3 modes (CPU rewrite, standard serial I/O, and parallel I/O mode)
Division of Erase Block See Figure 19.1 and Figure 19.2
Program Method Byte unit
Erase Method Block erase
Program, Erase Control Method Program and erase control by software command
Rewrite Control Method Rewrite control for blocks 0 and 1 by FMR02 bit in FMR0 register
Rewrite control for block 0 by FMR16 bit and block 1 by FMR16 bit
Number of Commands 5 commands
Programming
and erase
endurance
(1)
Blocks 0 and 1
(Program ROM)
R8C/20 Group: 100 times; R8C/21 Group: 1,000 times
Blocks A and B
(Data Flash)
(2)
10,000 times
ID Code Check Function Standard serial I/O mode supported
ROM Code Protect For parallel I/O mode supported
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