Section 25 Flash Memory
Rev. 1.00 Mar. 12, 2008 Page 986 of 1178
REJ09B0403-0100
25.6
Switching between User MAT and User Boot MAT
It is possible to alternate 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 should take place in boot mode or programmer mode.)
1. MAT switching by FMATS should always be executed from the on-chip RAM.
2. To ensure that the MAT that has been switched to is accessible, execute four NOP instructions
in the on-chip RAM immediately after writing to FMATS of the on-chip RAM (this prevents
access to the flash memory during MAT switching).
3. If an interrupt has occurred during switching, there is no guarantee of which memory MAT is
being accessed. Always mask the maskable interrupts before switching between MATs. In
addition, configure the system so that NMI interrupts do not occur during MAT switching.
4. After the 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 MAT switching,
transfer the interrupt-processing routines to the on-chip RAM and set the WEINTE bit in
FCCS 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 above the top of its 16-Kbyte memory space. If access
goes beyond the 16-Kbyte space, the values read are undefined.
<User MAT>
<On-chip RAM>
<User boot MAT>
Procedure for
switching to the
user boot MAT
Procedure for
switching to
the user MAT
Procedure for switching to the user boot MAT
(1) Mask interrupts
(2) Write H'AA to FMATS.
(3) Execute four 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 FMATS.
(3) Execute four NOP instructions before accessing
the user MAT.
Figure 25.19 Switching between the User MAT and User Boot MAT
Summary of Contents for H8S Family
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Page 70: ...Section 1 Overview Rev 1 00 Mar 12 2008 Page 22 of 1178 REJ09B0403 0100...
Page 108: ...Section 2 CPU Rev 1 00 Mar 12 2008 Page 60 of 1178 REJ09B0403 0100...
Page 116: ...Section 3 MCU Operating Modes Rev 1 00 Mar 12 2008 Page 68 of 1178 REJ09B0403 0100...
Page 152: ...Section 5 Interrupt Controller Rev 1 00 Mar 12 2008 Page 104 of 1178 REJ09B0403 0100...
Page 206: ...Section 6 Bus Controller BSC Rev 1 00 Mar 12 2008 Page 158 of 1178 REJ09B0403 0100...
Page 420: ...Section 9 14 Bit PWM Timer PWMX Rev 1 00 Mar 12 2008 Page 372 of 1178 REJ09B0403 0100...
Page 476: ...Section 12 Watchdog Timer WDT Rev 1 00 Mar 12 2008 Page 428 of 1178 REJ09B0403 0100...
Page 552: ...Section 14 CRC Operation Circuit CRC Rev 1 00 Mar 12 2008 Page 504 of 1178 REJ09B0403 0100...
Page 712: ...Section 18 I2 C Bus Interface IIC Rev 1 00 Mar 12 2008 Page 664 of 1178 REJ09B0403 0100...
Page 804: ...Section 19 LPC Interface LPC Rev 1 00 Mar 12 2008 Page 756 of 1178 REJ09B0403 0100...
Page 838: ...Section 20 Ethernet Controller EtherC Rev 1 00 Mar 12 2008 Page 790 of 1178 REJ09B0403 0100...
Page 964: ...Section 24 RAM Rev 1 00 Mar 12 2008 Page 916 of 1178 REJ09B0403 0100...
Page 1066: ...Section 25 Flash Memory Rev 1 00 Mar 12 2008 Page 1018 of 1178 REJ09B0403 0100...
Page 1098: ...Section 26 Boundary Scan JTAG Rev 1 00 Mar 12 2008 Page 1050 of 1178 REJ09B0403 0100...
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