HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 536

• Manufacturer Part Number: HD6417660
• Description: Renesas 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

17.5
17.5.1
The boot function is operated by the firmware that is stored in the boot ROM and functions on big
endian. Therefore, when the BOOT_E pin is asserted to its low level by a power-on reset
(RESETP = low), the MD5 pin should be driven low (big endian mode). After the specific
program has been downloaded, the boot function is branched to the start address in the initial
programming program for the external flash memory downloaded in the on-chip memory (U-
memory). The initial programming program needs to be specified to operate on big endian. To
execute normal operation on little endian, pay attention to the code alignment when the flash
memory is initially programmed.
17.5.2
The transfer rate of SCIF which communicates with an external host when the boot function is
used has the limitation shown in table 17.2. Note that a proper value should be set for the transfer
rate in the program for the external host, such as "exflash".
Table 17.2 Clock frequency and data transfer rate of SCIF when boot function is used
Rev. 1.00, 02/04, page 498 of 804
CPG setting
Mode 5
Clock ratio
Iφ:Bφ:Pφ = 2:2:1
Mode 7
Clock ratio
Iφ:Bφ:Pφ = 1:1:1/2
Usage Note
Endian when Using Boot Function
Clock Frequency and Data Transfer Rate when Using Boot Function
Input clock frequency
10MHz or more
13MHz or more
16MHz or more
20MHz or more
26MHz or more
32MHz or more
SCIF transfer rate
9600bps
19200bps
38400bps
9600bps
19200bps
38400bps