Datasheet

Section 22 Flash Memory
Rev. 3.00 Sep. 28, 2009 Page 702 of 910
REJ09B0350-0300
22.8.1 Boot Mode
Boot mode executes programming/erasing of the user MAT and the user boot MAT by means of
the control command and program data transmitted from the externally connected host via the on-
chip SCI_1.
In boot mode, the tool for transmitting the control command and program data, and the program
data must be prepared in the host. The serial communication mode is set to asynchronous mode.
The system configuration in boot mode is shown in figure 22.6. Interrupts are ignored in boot
mode. Configure the user system so that interrupts do not occur.
RxD1
T
xD1
Software for
analyzing
control
commands
(on-chip)
Flash
memory
On-chip
RAM
SCI_1
This LSI
Host
Programming
tool and program
data
Control command,
program data
Response
Figure 22.6 System Configuration in Boot Mode
(1) Serial Interface Setting by Host
The SCI_1 is set to asynchronous mode, and the serial transmit/receive format is set to 8-bit data,
one stop bit, and no parity.
When a transition to boot mode is made, the boot program embedded in this LSI is initiated.
When the boot program is initiated, this LSI measures the low period of asynchronous serial
communication data (H'00) transmitted consecutively by the host, calculates the bit rate, and
adjusts the bit rate of the SCI_1 to match that of the host.
When bit rate adjustment is completed, this LSI transmits 1 byte of H'00 to the host as the bit
adjustment end sign. When the host receives this bit adjustment end sign normally, it transmits 1
byte of H'55 to this LSI. When reception is not executed normally, initiate boot mode again. The
bit rate may not be adjusted within the allowable range depending on the combination of the bit
rate of the host and the system clock frequency of this LSI. Therefore, the transfer bit rate of the
host and the system clock frequency of this LSI must be as shown in table 22.8.