Arduino UNO Reference Design TM Reference Designs ARE PROVIDED "AS IS" AND "WITH ALL FAULTS". Arduino DISCLAIMS ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, REGARDING PRODUCTS, INCLUDING BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE USBVCC 1 GND 1 XT1R 4 3 1 EXP GND PAD 13 12 11 TXLED 10 RXLED 9 M8RXD 8 M8TXD 7 6 16MHz 2 1 Q2 2 5 RN1D 10K 4 1 UBOOT 2 USB boot En 1K 5 RN2D 4 C6 100n +5V XTAL2 2 4 6 ICSP GND ZIC1 1 10 9 21 20 22 7 8 RESET XTAL2 XTAL1 AREF AVCC AGND VCC GND (SCK)PB5 (MISO)PB4 (MOSI)PB3 (SS)PB2 (OC1)PB1 (ICP)PB0 (ADC5)PC5 (ADC4)PC4 (ADC3)PC3 (ADC2)PC2 (ADC1)PC1 (ADC0)PC0) (AIN1)PD7 (AIN0)PD6 (T1)PD5 (T0)PD4 (INT1)PD3 (INT0)PD2 (TXD)PD1 (RXD)PD0 GND TX YELLOW 1K 6 RN2C 3 XTAL1 1 16MHz XTAL2 R2 1M XTAL1 AREF +5V RX YELLOW 16MHz +5V 100n C5 DTR Y2 ATMEGA8U2-MU XT1 XT2 2 RESET GND ATMEGA8 M8RXD M8TXD GND 2 GROUND (CTS/HWB/AIN6/TO/INT7)PD7 (RTS/AIN5/INT6)PD6 (XCK/AIN4/PCINT12)PD5 (INT5/AIN3)PD4 (TXD1/INT3)PD3 (RXD1/AIN1/INT2)PD2 (AIN0/INT1)PD1 (OC0B/INT0)PD0 C9 22p C8 1u GND GND UCAP UVCC DD+ UGND 22 23 25 26 5 C10 22p 100n C7 VCC GND 27 31 30 29 28 VUCAP USBVCC RDRD+ UGND (INT4/ICP1/CLK0)PC7 (OC1A/PCINT8)PC6 (PCINT9/OC1B)PC5 (PCINT10)PC4 (AIN2/PCINT11)PC2 AVCC 21 20 19 18 17 MISO2 16 MOSI2 15 SCK2 14 C12 22p +5V 32 (PCINT7/OC0A/OC1C)PB7 (PCINT6)PB6 (PCINT5)PB5 RESET(PC1/DW) (T1/PCINT4)PB4 (PD0/MISO/PCINT3)PB3 (PDI/MOSI/PCINT2)PB2 XTAL2(PC0) (SCLK/PCINT1)PB1 (SS/PCINT0)PB0 XTAL1 RESET-EN 1 3 5 8 1 2 5 10K 6 RN1C 3 XT1 16MHz RD+ USHIELD BLM21 2 Y1 R3 27R 22R 5 RN3D 4 R1 RD- 1M GND 22R 8 RN3A 1 Q1 Z1 PGB1010604 Z2 DD+ XT2 PGB1010604 XUSB UGND 1 2 3 4 L1 P$2 P$1 P$2 P$1 USB X2 RESET2 USBVCC 500mA C11 22p F1 1 U3 +5V GND ICSP 3 4 RESET TS42 ICSP1 24 GND GND +5V 4 GND GND PC2 C2 47u 100n 1K 7 RN4B 2 1K 8 RN4A 1 19 18 17 16 15 14 SS IO9 IO8 28 27 26 25 24 23 AD5 AD4 AD3 AD2 AD1 AD0 13 12 11 6 5 4 3 2 IO7 IO6 IO5 IO4 IO3 IO2 IO1 IO0 GREEN ON 5 RN4D 1K 3 GND 6 RN4C 1K 2 +5V ICSP GND GND 1K VIN 1 2 3 4 5 6 1K RN2B +3V3 GND 2 4 6 GND +5V 2 POWER RESET GND 1 3 5 ADJ +5V C3 1u 4 7 GND NC/FB VO VI 5 +3V3 YELLOW L OUT EN 1 2 IN RN2A T1 FDN304V 3 3 1 PWRIN +5V + D1 M7 PC1 47u +5V 1 MC33269ST-5.0T3 IC2 GND MC33269D-5.0 VIN 2 1 GATE_CMD +5V 3 3 GND GND 4 2 GND GND LM358D + 4 C1 100n IN OUT 7 6 LM358D IC1 U1B 5 1 2 10K 8 RN1A 1 8 U1A 3 2 CMP +3V3 3 1 7 2 +5V RN1B 10K Arduino may make changes to specifications and product descriptions at any time, without notice. The Customer must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Arduino reserves these for future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them. The product information on the Web Site or Materials is subject to change without notice. Do not finalize a design with this information. VIN C4 100n AREF GND SCK MISO MOSI SS 8 7 6 5 4 3 2 1 13 12 11 10 9 8 IOH 6 5 4 3 2 1 2 3 IOL 6 RN3C 22R AD 8 7 6 5 4 3 2 1 7 RN3B 22R 7 6 5 4 3 2 1 0