H8SSLASH2214 datasheet(628/936 Pages) RENESAS

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Section 15 ROM

Rev.4.00 Sep. 18, 2008 Page 568 of 872

REJ09B0189-0400

(2) 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 15.12. 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'FFC000

H'FFDFFF

H'FFE000

H'FFEFBF

Programming

control program area

(8 kbytes)

Boot program area

(4 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 also that the boot program

remains in this area of the on-chip RAM even after control branches to the programming

control program.

Figure 15.12 RAM Areas in Boot Mode

(3) 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 RxD2 pin. The reset should end with RxD2 high. After the reset ends, it takes

approximately 100 states before the chip is ready to measure the low-level period of the RxD2

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 RxD2 and TxD2 pins should be pulled up on the board.

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