SH7280 Datasheet, PDF (1453/1726 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine family

Section 26 Flash Memory
1. The boot program embedded in this LSI is initiated on transition to USB boot mode. On
initiation of the USB boot program in this LSI, enumeration with the host proceeds.
When enumeration has been completed, transmit one byte with the value H'55 from the
host. If normal reception of this byte is not possible, re-boot into boot mode.
2. Inquiry information on the size, configuration, first address, state of support etc. for the
user mat is transmitted to the host.
3. Once the inquiry process is complete, the whole user mat is automatically erased.
4. A transition to waiting for programming or erasure follows automatic erasure of the user
mat. A transition to waiting for the data to be programmed follows reception of a
programming command. Erasure proceeds in the same way. Commands other than those
for programming and erasure are for sum checking and blank checking (checking of
erasure), reading from memory, and acquiring the current state information.
(3) Points to note regarding execution in USB boot mode
• A 48-MHz clock signal must be supplied to the USB module. Set the frequency of the external
clock or clock oscillator so that the dedicated USB clock (Uφ) runs at 48-MHz. For details,
refer to section 4, Clock Pulse Generator (CPG).
• Make the PC0 setting to select supply of the USB clock.
PC0 = 0: USBEXTAL and USBXTAL are used.
PC0 = 1: The system clock is used.
• When PC0 = 0, connect a 48-MHz oscillator across the USBEXTAL and USBXTAL pins.
• When PC0 = 1, connect USBEXTAL to the 0 level and leave USBXTAL open, and connect a
12-MHz oscillator across the EXTAL and XTAL pins.
• Use the PBIO pin for the D+ pull-up-control connection.
• To provide stabilization of the power supply during the programming and erasure of flash
memory, do not connect a cable via the password hub.
• If the USB cable is disconnected during the programming and erasure of flash memory, there
is a worst-case possibility of permanent destruction of the LSI circuit, so be particularly careful
on this point.
• In bus-power mode, transitions to software-standby mode as a low-power-consumption mode
do not proceed even if the USB enters suspension mode.
Rev. 1.00 Jun. 26, 2008 Page 1423 of 1692
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