Switching Between User Mat And User Boot Mat - Renesas H8SX/1520 Series Hardware Manual

17.11

Switching between User MAT and User Boot MAT

It is possible to switch between the user MAT and user boot MAT. However, the following
procedure is required because the start addresses of these MATs are allocated to the same address.
Switching to the user boot MAT disables programming and erasing. Programming of the user boot
MAT should take place in boot mode or programmer mode.
1. Memory MAT switching by FMATS should always be executed from the on-chip RAM.
2. When accessing the memory MAT immediately after switching the memory MATs by
FMATS from the on-chip RAM, similarly execute the NOP instruction in the on-chip RAM
for eight times (this prevents access to the flash memory during memory MAT switching).
3. If an interrupt request has occurred during memory MAT switching, there is no guarantee of
which memory MAT is accessed. Always mask the maskable interrupts before switching
memory MATs. In addition, configure the system so that NMI interrupts do not occur during
memory MAT switching.
4. After the memory MATs have been switched, take care because the interrupt vector table will
also have been switched. If interrupt processing is to be the same before and after memory
MAT switching, transfer the interrupt processing routines to the on-chip RAM and specify
VBR to place the interrupt vector table in the on-chip RAM.
5. Memory sizes of the user MAT and user boot MAT are different. When accessing the user
boot MAT, do not access addresses which exceed the 10-kbyte memory space. If an access is
equal to or greater than 10 kbytes, the read values are undefined.
<User MAT>
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<On-chip RAM>
Procedure for
switching to
user boot MAT
Procedure for
switching to
user MAT
Procedure for switching to the user boot MAT
1. Inhibit interrupts (mask).
2. Write H'AA to FMATS*.
3. Before access to the user boot MAT, execute the NOP instruction for eight times.
Procedure for switching to the user MAT
1. Inhibit interrupts (mask).
2. Write other than H'AA to FMATS*.
3. Before access to the user MAT, execute the NOP instruction for eight times.
Note: * Set the FLSHE bit in the system control register (SYSCR) to 1
when making access to FMATS.
Figure 17.20 Switching between User MAT and User Boot MAT
Section 17 Flash Memory (0.18-(m F-ZTAT Version)
<User boot MAT>
Rev. 3.00 Mar. 14, 2006 Page 629 of 804
REJ09B0104-0300