7641_06 Datasheet, PDF (101/385 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

7641 Group
HARDWARE
FLASH MEMORY MODE
Start
Single-chip mode, Memory expansion mode or
Boot mode
Set CPU mode registers A, B (Note 2)
Transfer CPU rewrite mode control program to
memory other than internal flash memory
Jump to control program transferred in memory
other than internal flash memory
(Subsequent operations are executed by control
program in this memory)
Set CPU rewrite mode select bit to “1” (by
writing “0” and then “1” in succession)
Setting
Check CPU rewrite mode entry flag
Using software command execute erase,
program, or other operation
Execute read array command or reset flash
memory by setting flash memory reset bit (by
writing “1” and then “0” in succession) (Note 3)
Write “0” to CPU rewrite mode select bit
Released
End
Notes 1: When starting the MCU in the single-chip mode or memory expansion mode, supply
4.5 V to 5.25 V to the CNVss pin until checking the CPU rewrite mode entry flag.
2: Set the main clock as follows depending on the XIN divider select bit of clock control
register (bit 7 of address 001F16):
When XIN divider select bit = “0” (φ = f(XIN)/4), the main clock is 24 MHz or less
When XIN divider select bit = “1” (φ = f(XIN)/2), the main clock is 12 MHz or less.
3: Before exiting the CPU rewrite mode after completing erase or program operation,
always be sure to execute the read array command or reset the flash memory.
Fig. 81 CPU rewrite mode set/release flowchart
Rev.2.00 Aug 28, 2006 page 84 of 113
REJ09B0336-0200