M30245 Datasheet, PDF (98/266 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M30245 Group
Vbus Detect
Vbus Detect
The Vbus Detect function will detect when the USB host is powered-up during USB self-powered operation. Self-
powered operation means the microcontroller has a power source external to the USB. This type of connection requires
the need to monitor when the USB host powers-up or powers-down. The other power mode, called Bus-powered
mode, means the microcontroller is powered directly from the USB Vbus connection. This type of connection does not
require the Vbus detect function because the microcontroller is actually powered from the USB so you know the USB
host is already powered-up.
The VbusDTCT pin is used for the Vbus detect function. When operating the USB in self-powered mode, connect the
Vbus line from the USB connector to the VbusDTCT pin. The Vbus detect function can be enabled or disabled in the USB
attach/detach register (bit 7 at address 001F16). Each time the USB host powers up or powers down, a Vbus detect
interrupt will be generated. This interrupt can be enabled or disable using the Vbus detect interrupt control register
(address 005C16). When a Vbus detect interrupt is received, the Vbus detect state bit located in the Port 9 data register
(bit 1 at address 03F116) should be read to determine if the Vbus is powered up or not.
Figure 1.67 is an example of the USB self-powered mode connection. Figure 1.68 shows the Vbus-related registers.
Vcc
To USB circuitry
Vbus
D+
D-
GND
VbusDTCT
D+
Vcc
UVcc
D-
Vss
M30245
Note: Not all necessary components are shown.
Figure 1.67. USB self-powered mode connection example
Address
Register name
~~ ^{001F16 USB Attach/Detach register}
~~ ^{005F16 Vbus detect interrupt control register}
03F1₁₆ Port P9
Acronym
~~USBAD
VBDIC
~~
P9
Figure 1.68. Vbus-related memory map
Rev.2.00 Oct 16, 2006 page 98 of 264
REJ03B0005-0200