atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 282

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

22.10 Registers description
22.10.1
282
ATmega32U4
USB general registers
Figure 22-13. Plug-in Detection Input Block Diagram
The control logic of the VBUS pad outputs a signal regarding the VBUS voltage level:
• 7-1 – Reserved
These bits are reserved. Do not modify these bits.
• 0 – UVREGE: USB pad regulator Enable
Set to enable the USB pad regulator. Clear to disable the USB pad regulator.
• 7 – USBE: USB macro Enable Bit
Set to enable the USB controller. Clear to disable and reset the USB controller, to disable the
USB transceiver and to disable the USB controller clock inputs.
• 6 – Reserved
The value read from these bits is always 0. Do not set these bits.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
• The “Session_valid” signal is active high when the voltage on the UVBUS pad is higher or
• The VBUS status bit is set when “Session_valid” signal is active (VBUS > 1.4V).
• The VBUSTI flag is set each time the VBUS state changes.
• The USB peripheral cannot attach to the bus while VBUS bit is not set.
equal to 1.4V. If lower than 1.4V, the signal is not active.
VBUS
USBE
R/W
R/W
7
0
7
0
-
R/W
R/W
6
0
-
6
0
-
Pad logic
FRZCLK
R/W
VDD
VSS
R
5
0
5
1
-
OTGPADE
R/W
Session_valid
R/W
4
0
-
4
0
R
3
0
-
R
3
0
-
USBSTA.0
VBUS
R
2
0
-
R
2
0
-
R
R/W
1
0
-
1
0
-
UVREGE
VBUSTE
R/W
R/W
0
0
0
0
VBUSTI
USBINT.0
UHWCON
USBCON
7766A–AVR–03/08