r5f71374an80fpv Renesas Electronics Corporation., r5f71374an80fpv Datasheet - Page 969

• Manufacturer Part Number: r5f71374an80fpv
• Description: 32-bit Risc Microcomputer Superh?? Risc Engine Family
• Manufacturer: Renesas Electronics Corporation.

22.8
22.8.1
It is possible to switch between the user MAT and user boot MAT. However, the following
procedure is required because these MATs are allocated to address 0.
(Switching to the user boot MAT disables programming and erasing. Programming of the user
boot MAT must take place in boot mode or programmer mode.)
1. MAT switching by FMATS should always be executed from the on-chip RAM. The SH
2. To ensure that the MAT that has been switched to is accessible, execute four NOP instructions
3. If an interrupt occurs during switching, there is no guarantee of which memory MAT is being
4. After the MATs have been switched, take care because the interrupt vector table will also have
5. Memory sizes of the user MAT and user boot MAT are different. When accessing the user
microcomputer prefetches execution instructions. Therefore, a switchover during program
execution in the user MAT causes an instruction code in the user MAT to be prefetched or an
instruction in the newly selected user boot MAT to be prefetched, thus resulting in unstable
operation.
in on-chip RAM immediately after writing to FMATS of on-chip RAM (this prevents access to
the flash memory during MAT switching).
accessed.
Always mask the maskable interrupts before switching MATs. In addition, configuring the
system so that NMI interrupts do not occur during MAT switching is recommended.
been switched.
If the same interrupt processings are to be executed before and after MAT switching or
interrupt requests cannot be disabled, transfer the interrupt processing routine to on-chip RAM,
and use the VBR setting to place the interrupt vector table in on chip RAM. In this case, make
sure the VBR setting change does not conflict with the interrupt occurrence.
boot MAT, do not access addresses exceeding the 12-Kbyte memory space. If access goes
beyond the 12-Kbyte space, the values read are undefined.
Usage Notes
Switching between User MAT and User Boot MAT
Rev. 1.00 Sep. 21, 2007 Page 943 of 1124
Section 22 Flash Memory
REJ09B0402-0100