Renesas H8S/2318 series, Hardware Manual

Page: 665 / 1121

Rev. 5.00, 12/03, page 635 of 1088
On-Chip RAM Area Divisions in Boot Mode: In boot mode, the 2-kbyte area from H'FFDC00
to H'FFE3FF is reserved for use by the boot program, as shown in figure 17-43. The area to which
the programming control program is transferred is H'FFE400 to H'FFFBFF. 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'FFDC00
H'FFE3FF
Programming
control program
area
(6 kbytes)
H'FFFBFF
Boot program
area
*
(2 kbytes)
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 17-43 RAM Areas in Boot Mode
Notes on Use of Boot Mode
•
When the chip comes out of reset in boot mode, it measures the low-level period of the input at
the SCI’s RxD1 pin. The reset should end with RxD1 high. After the reset ends, it takes
approximately 100 states before the chip is ready to measure the low-level period of the RxD1
pin.
•
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.
•
Interrupts cannot be used while the flash memory is being programmed or erased.
•
The RxD1 and TxD1 pins should be pulled up on the board.