D12320VF25V Datasheet, PDF (779/1146 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 17 ROM
<User MAT>
<On-chip RAM>
Procedure for
switching to the
user boot MAT
Procedure for
switching to
the user MAT
<User boot MAT>
Procedure for switching to the user boot MAT
[1] Mask interrupts
[2] Write H'AA to the FMATS register.
[3] Execute 4 NOP instructions before
accessing the user boot MAT.
Procedure for switching to the user MAT
[1] Mask interrupts
[2] Write a value other than H'AA to the FMATS register.
[3] Execute 4 NOP instructions before or after accessing
the user MAT.
Figure 17.79 Switching between the User MAT and User Boot MAT
17.27.1 Usage Notes
1. Download time of on-chip program
The programming program that includes the initialization routine and the erasing program that
includes the initialization routine are each 2 kbytes or less. Accordingly, when the CPU clock
frequency is 25 MHz, the download for each program takes approximately 164 μs at
maximum.
2. Write to flash-memory related registers by DTC
While an instruction in on-chip RAM is being executed, the DTC can write to the SCO bit in
FCCS that is used for a download request or FMATS that is used for MAT switching. Make
sure that these registers are not accidentally written to, otherwise an on-chip program may be
downloaded and damage RAM or a MAT switchover may occur and the CPU get out of
control. Do not use DTC to program FLASH related registers.
3. Compatibility with programming/erasing program of conventional F-ZTAT H8S
microcomputer
A programming/erasing program for flash memory used in the conventional F-ZTAT H8S
microcomputer which does not support download of the on-chip program by a SCO transfer
request cannot run in this LSI.
Be sure to download the on-chip program to execute programming/erasing of flash memory in
this LSI.
Rev.7.00 Feb. 14, 2007 page 745 of 1108
REJ09B0089-0700