Data Sheet
Reset.BringthislineLOWtoresetthemicrocontroller.Typicallyusedtoadda
resetbuttontoshieldswhichblocktheoneontheboard.
Communication
TheMicrohasanumberoffacilitiesforcommunicatingwithacomputer,another
boardoftheArduino&Genuinofamily,orothermicrocontrollers.The32U4
providesUARTTTL(5V)serialcommunication,whichisavailableondigitalpins0
(RX)and1(TX).TheATmega32U4alsoallowsforserial(CDC)communication over
USBandappearsasavirtualcomporttosoftwareonthecomputer.Thechipalso
actsasafullspeedUSB2.0device,usingstandardUSBCOMdrivers.OnWindows,
a.inffileis required.TheArduinoSoftware(IDE)includesaserialmonitorwhich
allowssimpletextualdatatobesenttoandfromtheboard.TheRXandTXLEDson
theboardwillflashwhendataisbeingtransmittedviatheUSBconnectiontothe
computer(butnotforserialcommunicationonpins0 and1).
ASoftwareSeriallibraryallowsforserialcommunication onotherMicro'sdigital
pins.
https://www.arduino.cc/en/Reference/SoftwareSerial
TheATmega32U4alsosupportsI2C(TWI)andSPIcommunication.TheArduino
Software(IDE)includesaWirelibrarytosimplifyuseoftheI2Cbus;see
thedocumentationfordetails.ForSPIcommunication,usetheSPIlibrary.
https://www.arduino.cc/en/Reference/Wire
https://www.arduino.cc/en/Reference/SPI
TheMicroappearsasagenerickeyboardandmouse,andcanbeprogrammedto
controltheseinputdevicesusingtheKeyboardandMouseclasses.
PhysicalCharacteristics
ThemaximumlengthandwidthoftheMicroPCBare4.8cmand1.77cm
respectively,withtheUSBconnectorextendingbeyondtheformerdimension.The
layoutallowsforeasyplacementonasolderlessbreadboard..
Automatic(Software)ResetandBootloaderInitiation
Ratherthanrequiringaphysicalpressoftheresetbuttonbeforeanupload,the
Microboardisdesignedinawaythatallowsittoberesetbysoftwarerunningon
aconnectedcomputer.TheresetistriggeredwhentheMicro'svirtual(CDC)serial
/COMportisopenedat1200baudandthenclosed.Whenthishappens,the
processorwillreset,breakingtheUSBconnectiontothecomputer(meaningthat
thevirtualserial/COMportwilldisappear).Aftertheprocessorresets,the