Datasheet

Section 22 ROM (Mask ROM Version, H8S/2148 F-ZTAT, H8S/2147N F-ZTAT, H8S/2144 F-ZTAT, and H8S/2142 F-ZTAT)
Rev. 4.00 Sep 27, 2006 page 659 of 1130
REJ09B0327-0400
On-Chip RAM Area Divisions in Boot Mode
In boot mode, the 128-byte area from H'(FF)FF00 to H'(FF)FF7F is reserved for use by the boot
program, as shown in figure 22.10. The area to which the programming control program is
transferred is H'(FF)E080 to H'(FF)EFFF (3968 bytes) in the 128-kbyte versions, or H'(FF)E880 to
H'(FF)EFFF (1920 bytes) in the 64-kbyte versions. The boot program area can be used when the
programming control program transferred into RAM enters the execution state. A stack area
should be set up as required.
H'(FF)E080
H'(FF)EFFF
Programming
control program
area
(3,968 bytes)
H'(FF)FF00
H'(FF)FF7F
Boot program
area
*
(128 bytes)
(a) 128-kbyte versions
H'(FF)E880
H'(FF)EFFF
Programming
control program
area
(1,920 bytes)
H'(FF)FF00
H'(FF)FF7F
Boot program
area
*
(128 bytes)
(b) 64-kbyte versions
Note: * The boot program area cannot be used until a transition is made to the execution state
for the programming control program transferred to RAM. Note that the boot program
remains stored in this area after a branch is made to the programming control program.
Figure 22.10 RAM Areas in Boot Mode
Notes on Use of User Mode
• When the chip comes out of reset in boot mode, it measures the low period of the input at the
SCI’s RxD1 pin. The reset should end with RxD1 high. After the reset ends, it takes about 100
states for the chip to get ready to measure the low period of the RxD1 input.
• In boot mode, if any data has been programmed into the flash memory (if all data is not 1), all
flash memory blocks are erased. Boot mode is for use when user program mode is unavailable,
such as the first time on-board programming is performed, or if the program activated in user
program mode is accidentally erased.