HD6433644R datasheet(145/549 Pages) RENESAS

145 / 549 page

Section 6 ROM

Rev. 6.00 Sep 12, 2006 page 125 of 526

REJ09B0326-0600

Boot mode can be exited by driving the reset pin low, then releasing 12 V application to the

TEST pin and FVPP pin at least 10 system clock cycles later, and setting the TEST pin to VSS to

release the reset.

However, external pin settings must not be changed during boot mode execution.

Note that the boot mode state is not maintained if 12 V application to the TEST pin is released

while in boot mode.

Also, if a watchdog timer reset occurs in this boot mode state, the built-in boot program will be

restarted without clearing the MCU’s internal mode state.

7. If the TEST pin input level is changed (e.g. from 0 V to 5 V to 12 V) during a reset (while a

low level is being input at the

RES pin), port states will change as a result of the change of

MCU operating mode. Therefore, care must be taken to make pin settings to prevent these pins

from becoming output signal pins during a reset, and to prevent collision with signals outside

the MCU.

8. Regarding 12 V application to the FVPP and TEST pins, insure that peak overshoot does not

exceed the maximum rating of 13 V.

Also, be sure to connect bypass capacitors to the FVPP and TEST pins.

Note: * For further information on VPP application, release, and cut-off, see note 5 in section

6.9, Flash Memory Programming and Erasing Precautions.

6.6.2

User Program Mode

When set to user program mode, the H8/3644F, H8/3643F, or H8/3642AF can program and erase

its flash memory by executing a user program. Therefore, on-board reprogramming of the on-chip

flash memory can be carried out by providing on-board means of supplying VPP and programming

data, and storing an on-board reprogramming program in part of the program area.

User program mode is selected by applying 12 V to the FVPP pin when flash memory is not being

accessed, during a reset or after confirming that a reset has been performed properly (after the

reset is released).

The flash memory cannot be read while being programmed or erased, so the on-board

reprogramming program or flash memory reprogramming routine should be transferred to the

RAM area, and on-board reprogramming executed in that area.

HD6433644R Datasheet(PDF) 145 Page - Renesas Technology Corp