
deveopmen
CPU Rewrite Mode (Flash Memory Version)
Preliminary Specifications REV.D
Specifications in this manual are tentative and subject to change.
Mitsubishi microcomputers
M16C/80 (100-pin version) group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
261
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 3)
Single-chip mode, memory expansion
mode, or boot mode
Set processor mode register (Note 1)
Using software command execute erase,
program, or other operation
(Set lock bit disable bit as required)
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
Note 1: During CPU rewrite mode, set the main clock frequency as shown below using the main clock division
register (address 000C
16
):
6.25 MHz or less when wait bit (bit 2 at address 0005
16
) = “0” (without internal access wait state)
12.5 MHz or less when wait bit (bit 2 at address 0005
16
) = “1” (with internal access wait state)
Note 2: For CPU rewrite mode select bit to be set to “1”, the user needs to write a “0” and then a “1” to it in
succession. When it is not this procedure, it is not enacted in “1”. This is necessary to ensure that no
interrupt or DMA transfer will be executed during the interval.
Note 3: 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.
Note 4: “1” can be set. However, when this bit is “1”, user ROM area is accessed.
(Boot mode only)
Write “0” to user ROM area select bit (Note 4)
Write “0” to CPU rewrite mode select bit
(Boot mode only)
Set user ROM area select bit to “1”
Set CPU rewrite mode select bit to “1” (by
writing “0” and then “1” in succession)(Note 2)
*1
*1
Program in ROM
Program in RAM
Figure 1.30.2. CPU rewrite mode set/reset flowchart