M16C26 Datasheet, PDF (193/239 Pages) Renesas Technology Corp – 16-BIT CMOS SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/20 SERIES

Udenvdeelropment
Preliminary Specifications Rev. 0.9
Specifications in this manual are tentative and subject to change.
CPU Rewrite Mode (Flash Memory Version)
M16C/26 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
commands.
In CPU rewrite mode (whether EW0 or EW1), make sure all software commands and data are written to
and read from even addresses (byte address Ao = 0) in 16 bit units. Make sure the write data is written in
16 bit units beginning with an even address. Writing in 16 bit units beginning with an odd address and
writing in 8 bit units are inhibited. When using 8-bit software commands, always be sure to write to even
addresses. Writing to odd addresses has no effect.
Use software commands to control program and erase operations. Whether program and erase opera-
tions have terminated normally or in error can be verified by reading the status register. Even when
reading the status register, set to even addresses in the user ROM area also.
EW1 mode (CPU rewrite mode)
In EW1 mode, operation is executed using the control program residing in the internal flash memory.
Unlike in EW0 mode, there is no need to transfer the control program to other than the internal flash
memory (e.g., internal RAM). However, make sure the control program is located in the 64-Kbyte user
block or 4-Kbyte data block.
For EW1 mode, set the EW0 mode select bit (address 01B716, bit 1) to 1 (by writing 0 and then 1 in
succession) and set the EW1 mode select bit (address 01B516, bit 6) to 1 (by writing 0 and then 1 in
succession). This places the microcomputer in EW1 mode, ready to accept software commands. Al-
though software commands operate the same way as in EW0 mode, there are following differences.
(1) Do not perform Block Erase or Program operations on control program execution blocks (blocks in
which the control program is located).
(2) Do not execute the Read Status Register command. (In EW1 mode, this command has no effect.)
After erase and program operations are completed during EW1 mode, the microcomputer is in read
array mode, and not in read status mode. (During EW0 mode, the microcomputer is in read status
mode after operations are completed.)
Therefore, to verify whether program or erase operations have terminated normally or in error, read the
flash memory control register 0. Be aware that during EW1 mode, the status register cannot be read.
During EW1 mode, the CPU remains in a hold state while executing erase and program operations. The
ports retain the status in which they were before commands were issued. (They do not go Hi-Z even while
executing erase or program operations.)
After erase or program operations are completed, the CPU restarts execution of the rest of the control
program.
While erase or program operations are underway in EW1 mode, make sure that no interrupts except
NMI, watchdog timer, and reset will be generated, and that no DMA transfers will be committed.
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