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5. This LSI terminates transmit and receive operations by the on-chip SCI(channel 1) (by clearing
the RE and TE bits in serial control register (SCR)) before branching to the user program.
However, the adjusted bit rate is held in the bit rate register (BRR). At this time, the TXD
is in the high level output state (P9DDR P9
Before branching to the user program the value of the general registers in the CPU are also
undefined. Therefore, the general registers must be initialized immediately after control
branches to the user program. Since the stack pointer (SP) is implicitly used during subroutine
call, etc., a stack area must be specified for use by the user program.
There are no other internal I/O registers in which the initial value is changed.
6. Transition to the boot mode executes a reset-start of this LSI after setting the MD
FWE pins according to the mode setting conditions shown in table 18.5.
At this time, this LSI latches the status of the mode pin inside the microcomputer to maintain
the boot mode status at the reset clear (startup with Low→ High) timing *
To clear boot mode, it is necessary to drive the FWE pin low during the reset, and then execute
reset release *
1
. The following points must be noted:
Before making a transition from the boot mode to the regular mode, the microcomputer
boot mode must be reset by reset input via the RES pin. At this time, the RES pin must be
hold at low level for at least 20 system clock. *
Do not change the input levels at the mode pins (MD
boot mode. When making a mode transition, first enter the reset state by inputting a low
level to the RES pin. When a watchdog timer reset was generated in the boot mode, the
microcomputer mode is not reset and the on-chip boot program is restarted regardless of
the state of the mode pin.
Do not input low level to the FWE pin while the boot program is executing and when
programming/erasing flash memory. *
7. If the mode pin and FWE pin input levels are changed from 0 V to V
during a reset (while a low level is being input to the RES pin), the microcomputer's operating
mode will change.
Therefore, since the state of the address dual port and bus control output signals (CSn, RD,
HWR, LWR) changes, use of these pins as output signals during reset must be disabled outside
the microcomputer.
DDR=1, P9DR P9
1
1
3
to MD
2
2
Rev. 3.00 Mar 21, 2006 page 579 of 814
Section 18 ROM
DR=1).
to MD
0
1
.
) or the FWE pin while in
0
or from V
to 0V
CC
CC
REJ09B0302-0300
pin
1
and
2
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