HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 529

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

This LSI has a boot function which is used to download, to the on-chip memory, the firmware
needed for the initial programming of the external flash memory. This function enables updating
programs and dumping contents after the flash memory has been mounted on the board. This
function eliminates the need to provide external address and data buses for the programming of the
flash memory when this LSI and the flash memory, in bare-chip form, are sealed in a single
package. This makes it possible to dramatically reduce the number of pins.
17.1
• Automatic downloading of the initial programming program from SCIF0
• Automatic bit-rate adjustment
• High-speed execution of the downloaded program in on-chip memory
• Execution of the downloaded program starts automatically on completion of downloading
Note: Since the boot function is configured as a single circuit module, it is one of the target
Figure 17.1 shows the block diagram of the boot function (BOOT). The I/O pins for the bus state
controller (BSC) (A23 to A0, D15 to D0, WE1 to WE0, CS0, and RD) are connected to the
external flash memory and the I/O pins for the SCIF0 (SCIF0_RxD and SCIF0_TxD) are
connected to the external host.
The operation of downloading, via the SCIF0, the initial programming program of the external
flash memory to the on-chip memory (U memory), starts after a power-on reset. This transfer
is synchronous and via the UART. This allows the downloading of any initial programming
program according to the type of the external flash memory that is connected. If the
specification defined in this section is conformed to, programs for purposes other than the
initial programming of the external flash memory may be downloaded. The size of the
program to be downloaded must be no more than 8,192 bytes and is otherwise freely
determined.
Automatic adjustment of the bit-rate at which the program is downloaded via the SCIF0 is
possible.
Since the program downloaded from the SCIF0 is expanded in the on-chip RAM, it is
executable at high speed.
After the specific program has been downloaded, processing automatically branches to the
start address (H'A55F0000) in the downloaded program. Execution thus automatically starts.
modules for power control by the module-standby function. The boot function is only
necessary for boot processing. If, therefore, power consumption needs to be reduced in
normal operation or in the sleep state, we recommend that the supply of the clock signal to
the boot-function module be stopped by setting the MSTP43 bit in STBCR4 to 1. For
details on the module-standby function, refer to section 13, Power-Down Modes.
Features
Section 17 Boot Function (BOOT)
Rev. 1.00, 02/04, page 491 of 804