Datasheet

Section 22 Flash Memory
R01UH0309EJ0500 Rev. 5.00 Page 1167 of 1408
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
22.10 USB Boot Mode
USB boot mode executes programming/erasing of the user ROM by means of the control
command and program data transmitted from the externally connected host via the USB.
In USB boot mode, the tool for transmitting the control command and program data, and the
program data must be prepared in the host. The system configuration in USB boot mode is shown
in figure 22.8. Interrupts are ignored in USB boot mode. Configure the user system so that
interrupts do not occur.
Host or
self-power HUB
Programming tool
and program data
Software for
analyzing
control
commands
(on-chip)
This LSI
Flash
memory
On-chip
RAM
USB
P27 and P26
MD2 to MD0P20
01, 10, 11 (depending on the
input frequency)
011
P17
0: Self power setting
1: Bus power setting
VBUS
USB+
USB-
Rs
Data transmission/
reception
Rs
1.5 kΩ
Figure 22.8 System Configuration in USB Boot Mode