gavinlyonsrepo/timer_arduino_two

Countdown Timer: Range 1-99 minutes. Output time (mm:ss) to seven segment display and Audio to Buzzer. Input: Push button to start. Potentiometer used for time select.

Overview

• Name: timer_arduino_two
• Title: Micro-controller Countdown Timer
• Description: Countdown Timer: Range 1-99 minutes. Output time (mm:ss) to seven segment display and Audio to Buzzer. Input: Push button to start. Potentiometer used for time select.
• Author: Gavin Lyons
• URL: https://github.com/gavinlyonsrepo/timer_arduino_two

libraries used

None

Software Used

Arduino IDE 1.8.5

Eagle 9.3.0

Parts List

The schematic drawn in Eagle is in documents section.

You will need following parts.

ATmega328p micro-controller as per schematic or alternatively a Arduino uno/nano module.

Resistors: 20 ohms , 220 ohms, 660 ohms, 10K , 500ohms X 7, 1K X 4

Transistors 4 X 2N2222 NPN

One 4 digit seven segment module (SMA420564)

one 50 k potentiometer

one pushbutton

One on/off SPST switches

One piezo buzzer passive

One 16 Mhz crystal

One Lm317 voltage regulator

Capacitors. two x 22pF, three x 100nF , 1uF

Features

The user selects the countdown time (1-99 minutes) with the potentiometer then starts with the pushbutton. Time remaining is displayed on seven segment display. When finished the buzzer is activated and Zero displayed on 4 digit 7-segment display for a few minutes, The unit then shuts off display and buzzer.

LED Array Pin Layout

Pin Uno	Pin Atmega	7 Segment pin
D2	PD2	a
D3	PD3	b
D4	PD4	c
D5	PD5	d
D6	PD6	e
D7	PD7	f
D8	PB0	g
n/c	n/c	p
D10	PB2	d4
D11	PB3	d3
D12	PB4	d2
D13	PB5	d1

The 4-digit seven segment display (SMA420564 or SM420564) is a common-cathode display.
4 Digit 7 Segment Cathode Red LED Display 0.56" SM420564.

Schematic

Copyright

Copyright (C) 2019 Gavin Lyons see LICENSE.md in documentation section for more details