I want to use a USB connection with the ATmega32u4, but there are 6 pins in the datasheet (http://www.atmel.com/Images/doc7766.pdf) associated with the USB. I don't know which ones connect to the generic USB connections. Can someone show me how they are setup?

  • \$\begingroup\$ Link above to the spec is not valid (apr 2016). What is best point to start read about own software with USB protocol? Precise: raw chip, not arduino. \$\endgroup\$ – Jacek Cz Apr 3 '16 at 20:07

Section 21, "USB controller", subsection 21.3, "Typical Application Implementation", of the datasheet shows methods of connecting the device along with associated components to USB in various bus- or self-powered configurations.

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  • \$\begingroup\$ Thank you! But can you tell me why the USB has five connections? What is the fifth one at the bottom of the diagram do? \$\endgroup\$ – Jdude2345 Jan 4 '15 at 0:03
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    \$\begingroup\$ electronics.stackexchange.com/questions/35462/… \$\endgroup\$ – Ignacio Vazquez-Abrams Jan 4 '15 at 0:07
  • \$\begingroup\$ NO in the diagram. On the Datasheet listed \$\endgroup\$ – Jdude2345 Jan 4 '15 at 0:08
  • \$\begingroup\$ If you are not talking about the OTG ID pin (which you can leave unconnected), then give the name of the signal you are asking about. \$\endgroup\$ – Chris Stratton Jan 4 '15 at 3:53

To connect this ATmega on USB, you should connect:
Pin 3 (D-) with a 22 Ohm resistor in serial connected at pin 2(D-) of USB
Pin 4 (D+) with a 22 Ohm resistor in serial connected at pin 3 (D+) of USB
pin 35 (GND) connected at pin 1 of (GND)USB
pin 34 (VCC) connected at pin 4 of (VCC)USB

enter image description here

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