
R8C/3GM Group
31. Flash Memory
R01UH0284EJ0100 Rev.1.00
Aug 09, 2011
31. Flash Memory
The flash memory can perform in the following three rewrite modes
: CPU rewrite mode, standard serial I/O mode, and
parallel I/O mode.
31.1
Overview
Notes:
1. To perform programming and erasure, use VCC = 2.7 V to 5.5 V as the supply voltage. Do not perform
programming and erasure at less than 2.7 V.
2. 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 = 1,000 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 erase count can be
reduced by executing program 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.
for details.
Table 31.1
Flash Memory Version Performance
Item
Specification
Flash memory operating mode
3 modes (CPU rewrite, standard serial I/O, and parallel I/O)
Division of erase blocks
Programming method
Byte units
Erasure method
Block erase
Programming and erasure control method
(1)Program and erase control by software commands
Rewrite control
method
Blocks 0 to 3
Rewrite protect control in block units by the lock bit
Blocks A, B, C, and D
(Data flash)
Individual rewrite protect control on blocks A, B, C, and D
by bits FMR14, FMR15, FMR16, and FMR17 in the FMR1 register
Number of commands
7 commands
Programming and
Blocks 0 to 3
1,000 times
Blocks A, B, C, and D
(Data flash)
10,000 times
ID code check function
Standard serial I/O mode supported
ROM code protection
Parallel I/O mode supported
Table 31.2
Flash Memory Rewrite Mode
Flash Memory
Rewrite Mode
CPU Rewrite Mode
Standard Serial I/O Mode
Parallel I/O Mode
Function
User ROM area is rewritten by
executing software commands
from the CPU.
User ROM area is rewritten
using a dedicated serial
programmer.
User ROM area is rewritten
using a dedicated parallel
programmer.
Rewritable area
User ROM
Rewrite programs
User program
Standard boot program
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