Datasheet ATmega328/P - Summary (Microchip) - 10

Figure 5-2. 28-pin MLF Top View
Power 1) Ground Programming/debug 3/PCINT1 Digital Analog Crystal/CLK PD2 (INT0/PCINT18) PD1 (TXD/PCINT17) PD0 (RXD/PCINT16) PC6 (RESET/PCINT14) PC5 (ADC5/SCL/PCINT13) PC4 (ADC4/SDA/PCINT12) PC3 (ADC 28 27 26 25 24 23 22 (PCINT19/OC2B/INT1) PD3 1 PC2 (ADC2/PCINT10) 21 (PCINT20/XCK/T0) PD4 2 PC1 (ADC1/PCINT9) 20 VCC 3 19 PC0 (ADC0/PCINT8) GND 4 18 GND (PCINT6/XTAL1/TOSC1) PB6 5 17 AREF (PCINT7/XTAL2/TOSC2) PB7 6 16 AVCC (PCINT21/OC0B/T1) PD5 7 15 PB5 (SCK/PCINT5) 8 9 10 11 12 13 14 Bottom pad should be soldered to ground PD6 PB3 (PCINT23/AIN1) PD7 (PCINT1/OC1A) PB1 (PCINT4/MISO) PB4 (PCINT2/SS/OC1B) PB2 (PCINT0/CLKO/ICP1) PB0 (PCINT22/OC0A/AIN0) (PCINT3/OC2A/MOSI) Atmel ATmega328/P [DATASHEET] 10 Atmel-42735B-328/P_Datasheet_Summary-11/2016 Document Outline Introduction Feature Table of Contents 1. Description 2. Configuration Summary 3. Ordering Information 3.1. ATmega328 3.2. ATmega328P 4. Block Diagram 5. Pin Configurations 5.1. Pin-out 5.2. Pin Descriptions 5.2.1. VCC 5.2.2. GND 5.2.3. Port B (PB[7:0]) XTAL1/XTAL2/TOSC1/TOSC2 5.2.4. Port C (PC[5:0]) 5.2.5. PC6/RESET 5.2.6. Port D (PD[7:0]) 5.2.7. AVCC 5.2.8. AREF 5.2.9. ADC[7:6] (TQFP and VFQFN Package Only) 6. I/O Multiplexing 7. Resources 8. Data Retention 9. About Code Examples 10. Capacitive Touch Sensing 10.1. QTouch Library 11. Packaging Information 11.1. 32-pin 32A 11.2. 32-pin 32M1-A 11.3. 28-pin 28M1 11.4. 28-pin 28P3