HD64F2638F20J Datasheet, PDF (925/1512 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2600 Series

H8S/2639, H8S/2638, H8S/2636,
H8S/2630, H8S/2635 Group
Section 21C ROM
(H8S/2635 Group)
On-Chip RAM Area Divisions in Boot Mode: In boot mode, the RAM area is divided into an
area used by the boot program and an area to which the programming control program is
transferred via the SCI, as shown in figure 21C-9. The boot program area cannot be used until the
execution state in boot mode switches to the programming control program transferred from the
host.
H'FFE000
Programming
control program area
(2 kbytes)
Boot program area
(1.9 kbytes)
H'FFE7FF
H'FFE800
H'FFEFBF
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 also that the boot program
remains in this area of the on-chip RAM even after control branches to the programming
control program.
Figure 21C-9 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.
REJ09B0103-0800 Rev. 8.00
May 28, 2010
Page 875 of 1458