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HARDWARE
3850 Group (Spec. H) User’s Manual
FUNCTIONAL DESCRIPTION
1-42
Fig. 45 Flash memory control registers
Fig. 46 CPU rewrite mode set/reset flowchart
Flash memory control register
SymbolAddressWhen reset
FMCR0FFE16
XXX00001
W
R
b7
b5
b4
b2
b1
b0
FMCR0
Bit symbol
Bit nameFunction
R W
0: Busy (being written or erased)
1: Ready
CPU rewrite mode
select bit (Note 2)
0: Normal mode
(Software commands invalid)
1: CPU rewrite mode
(Software commands acceptable)
FMCR1
CPU rewrite mode
entry flag
Flash memory reset bit
(Note 3)
0: Normal operation
1: Reset
FMCR2
FMCR3
RY/BY status flag
0: Normal mode
(Software commands invalid)
1: CPU rewrite mode
(Software commands acceptable)
Nothing is assigned.
When write, set “0”. When read, values are indeterminate.
User area / Boot area
selection bit
0: User ROM area
1: Boot ROM area
FMCR4
b3
b6
Notes 1: The contents of the flash memory control register after reset is released become
“XXX00001”.
2: For this bit to be set to “1”, write “0” and then “1” to bit 1 in succession.
3: In order to perform flash memory reset by this bit setup, while the CPU rewriting
mode selection bit is set to “1”, write “1” to bit 3. In order to reset release, write “0”
to bit 3 in the next.
End
Start
Execute read array command or reset flash
memory by setting flash memory reset bit (by
writing “1” and then “0” in succession) (Note 2)
Single-chip mode, or boot mode
Set CPU mode register (Note 1)
Using software command execute erase,
program, or other operation
Jump to transferred control program in RAM
(Subsequent operations are executed by control
program in this RAM)
Transfer CPU rewrite mode control
program to internal RAM
Notes 1: Set bit 6, 7 (Main clock division ratio selection bits ) at CPU mode register (003B16).
2: Before exiting the CPU rewrite mode after completing erase or program operation, always be sure to
execute a read array command or reset the flash memory.
Write “0” to CPU rewrite mode select bit
Set CPU rewrite mode select bit to “1” (by
writing “0” and then “1” in succession)
Check the CPU rewrite mode entry flag
*1
Program in ROM
Program in RAM