19.3.1
Boot Mode
To use boot mode, a user program for programming and erasing the flash memory must be
provided in advance on the host machine (which may be a personal computer). Serial
communication interface channel 1 is used in asynchronous mode. If the H8/3334YF is placed in
boot mode, after it comes out of reset, a built-in boot program is activated. This program starts by
measuring the low period of data transmitted from the host and setting the bit rate register (BRR)
accordingly. The H8/3334YF’s built-in serial communication interface (SCI) can then be used to
download the user program from the host machine. The user program is stored in on-chip RAM.
After the program has been stored, execution branches to address H'FBE0 in the on-chip RAM,
and the program stored on RAM is executed to program and erase the flash memory. Figure 19.4
shows the boot-mode execution procedure.
H8/3334YF
Receive data to be programmed
RxD1
SCI
TxD1
HOST
Transmit verification data
Figure 19.3 Boot-Mode System Configuration
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RENESAS [ RENESAS TECHNOLOGY CORP ]
