Datasheet

Section 20 Flash Memory (F-ZTAT Version)
Rev. 6.00 Mar. 18, 2010 Page 733 of 982
REJ09B0054-0600
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.
2. SCI should be set to asynchronous mode, and the transfer format as follows: 8-bit data, 1 stop
bit, and no parity.
3. When the boot program is initiated, the chip measures the low-level period of asynchronous
SCI communication data (H'00) transmitted continuously from the host. The chip then
calculates the bit rate of transmission from the host, and adjusts the SCI bit rate to match that
of the host. The reset should end with the RxD pin high. The RxD and TxD pins should be
pulled up on the board if necessary. After the reset is complete, it takes approximately 100
states before the chip is ready to measure the low-level period.
4. After matching the bit rates, the chip transmits one H'00 byte to the host to indicate the
completion of bit rate adjustment. The host should confirm that this adjustment end indication
(H'00) has been received normally, and transmit one H'55 byte to the chip. If reception could
not be performed normally, initiate boot mode again by a reset. Depending on the host’s
transfer bit rate and system clock frequency of this LSI, there will be a discrepancy between
the bit rates of the host and the chip. To operate the SCI properly, set the host’s transfer bit rate
and system clock frequency of this LSI within the ranges listed in table 20.5.
5. In boot mode, a part of the on-chip RAM area is used by the boot program. The area
H'FFC000 to H'FFDFFF is the area to which the programming control program is transferred
from the host. The boot program area cannot be used until the execution state in boot mode
switches to the programming control program.
6. Before branching to the programming control program, the chip terminates transfer operations
by SCI (by clearing the RE and TE bits in SCR to 0), however the adjusted bit rate value
remains set in BRR. Therefore, the programming control program can still use it for transfer of
write data or verify data with the host. The TxD pin is high. The contents of the CPU general
registers are undefined immediately after branching to the programming control program.
These registers must be initialized at the beginning of the programming control program, as the
stack pointer (SP), in particular, is used implicitly in subroutine calls, etc.
7. Boot mode can be cleared by driving the reset pin low, waiting at least 20 states, then setting
the FWE pin and mode pins, and executing reset release*. Boot mode is also cleared when a
WDT overflow occurs.
8. All interrupts are disabled during programming or erasing of the flash memory.
Note: * The input signals on the FWE and mode pins must satisfy the mode programming
setup time (t
MDS
= 200 ns) at the reset release timing.