h8s-2635 Renesas Electronics Corporation., h8s-2635 Datasheet - Page 883

• Manufacturer Part Number: h8s-2635
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

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 21B-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.
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.
Before branching to the programming control program (RAM area H'FFC000), the chip
terminates transmit and receive operations by the on-chip SCI (channel 1) (by clearing the RE
Section 21B ROM (H8S/2638 Group, H8S/2639 Group, H8S/2630 Group)
Figure 21B-9 RAM Areas in Boot Mode
Rev. 6.00 Feb 22, 2005 page 823 of 1484
REJ09B0103-0600