| Component Type | Reference | Description | Quantity | Possible Sources and Notes |
| PCB | | ATmega Alarm Clock PCB | 1 | Order from OSH Park or your favorite PCB manufacturer using attached Gerber files. |
| Battery Holder | BT1 | Battery holder for CR2032 battery; Through Hole | 1 | Mouser 712-BAT-HLD-001-THM |
| Battery | BT1 | CR2032 lithium battery | 1 | Mouser 658-CR2032, or buy locally
Note: Due to shipping restrictions battery is not included in Mouser's project BOM. |
| Capacitor | C1 - C6 | 100 nF (0.1 uF) multilayer ceramic capacitor; 0603 SMT | 6 | Mouser 77-VJ0603Y104JXJPBC |
| Capacitor | C7, C8 | 47 pF multilayer ceramic capacitor; 0603 SMT | 2 | Mouser 77-VJ0603A470JXACBC |
| Capacitor | C9 | 10 uF, 10V multilayer ceramic capacitor, 0805 SMT | 1 | Mouser 77-VJ0805G106KXQTBC |
| LED | D1 | Green LED, 0603 SMT | 1 | Mouser 78-VLMTG1300-GS08 or 78-VLMG1300-GS08 |
| LED | D2 | Blue LED, 0603 SMT | 1 | Mouser 78-VLMB1300-GS08 |
| LED | D3 | Yellow LED, 0603 SMT | 1 | Mouser 78-VLMY1300-GS08 |
| LED | D4 | Red LED, 0603 SMT | 1 | Mouser 78-VLMS1300-GS08 |
| Standoffs | HOLE1 - HOLE 4 | 11 mm standoffs, 2.5 mm thread | 4 | Mouser 761-M1258-2545-AL |
| Screws | HOLE1 - HOLE 4 | 2.5 mm screw | 8 | Mouser 534-29301 |
| Connector | P1 | Mini USB Type B Socket, Through Hole | 1 | Mouser 710-651005136521 |
| Header | P2 | 8x2 female connector; straight; 2.54 mm lead spacing | 1 | Mouser 517-929975-01-08-RK |
| Header | P3 | 4 pin connector, 2 mm pitch, Through Hole | 1 | Mouser 538-35362-0450
Note: Optional, for connecting additional I2C devices |
| Header | P4 | 5x1 header; straight; 2.54 mm lead spacing | 1 | Mouser 855-M20-9990545
Note: Optional, for connecting additional devices, solder on the back side of the board, or attach wires directly to the PCB. |
| Header | P5 | 3x2 header, straight; 2.54 mm lead spacing | 1 | Mouser 855-M20-9980345
Note: Optional, used for ICSP |
| Transistor | Q1 | PMBT2222A, SOT-23 SMT | 1 | Mouser 771-PMBT2222A235 |
| Resistor | R1, R2 | 27 ohm resistor, 0603 SMT | 2 | Mouser 71-CRCW0603-27-E3 |
| Resistor | R3 - R6 | 1 kohm resistor, 0603 SMT | 4 | Mouser 71-CRCW0603-1.0K-E3 |
| Resistor | R7, R8 | 2.2 kohm resistor, 0603 SMT | 2 | Mouser 71-CRCW0603-2.2K-E3 |
| Resistor | R9 | 10 kohm resistor, 0603 SMT | 1 | Mouser 71-CRCW0603-10K-E3 |
| Resistor | R10 | 1 Mohm resistor, 0603 SMT | 1 | Mouser 71-CRCW06031M00FKEB |
| Trimming Potentiometer | RV1 | 10 kohm | 1 | Mouser 652-3362P-1-103LF
Note: Used to adjust LCD module contrast and viewing angle. In some cases might be replaced with a jumper to VCC or GND |
| Speaker | SP1 | 9 mm piezoelectric transducer | 1 | Mouser 497-TP094003-1 |
| Tactile Switch | SW1 - SW4 | Tactile switch; 6 mm; right angle | 4 | Mouser 653-B3F-3150 (projected), 653-B3F-3100 (flat) |
| Tactile Switch | SW5 | Tactile switch; 6 mm; straight | 1 | Mouser 653-B3F-1000 |
| Tactile Switch Key Top | SW1, SW2 | Round, Black | 2 | Mouser 653-B32-2010 |
| Tactile Switch Key Top | SW3, SW4 | D-type, Black | 2 | Mouser 653-B322110 |
| Integrated Circuit | U1 | Atmel ATmega328P Microcontroller, PDIP-28 | 1 | Mouser 556-ATMEGA328P-PU |
| Integrated Circuit | U2 | Maxim DS3231M RTC, SOIC-8 | 1 | Mouser 700-DS3231MZ+ |
| Integrated Circuit | U3 | FTDI FT231XS USB to serial interface, SSOP-20 | 1 | Mouser 895-FT231XS-R |
| IC Socket | U1 | IC socket 28-pin 300 mil | 1 | Mouser 517-4828-3004-CP |
| Quartz Crystal Resonator | X1 | 16 MHz ceramic resonator with integrated load capacitors | 1 | Mouser 81-CSTCE16M0V53-R0 |
