Summary of PIC16F84 Digital Clock / Silent Alarm
This article details "Silent Alarm," a digital clock project from 2006 using a Microchip PIC 16F84A microcontroller. Designed for gentle wake-ups, it features a vibration motor instead of sound and uses seven-segment displays for timekeeping. The author explains the simple circuit design and software logic, which ensures equal brightness across all displays and controls the alarm via a transistor-driven relay.
Parts used in the Silent Alarm:
- PIC 16F84A Microcontroller
- 7447 BCD to 7 Segment Decoder
- Four Seven Segment Displays
- Three 5 mm Red LEDs
- 2N2222 Transistor
- Relay
- Three Push Buttons
- Three 1K Ohm Resistors
- Vibration Motor
This is one of my earliest projects as a maker.
Actually, I’ve been doing so since I was a little child. And this one is from my early days in Embedded Software.
This is a digital clock project that I’ve working on since 2006. It’s calledSilent Alarm.
It’s one of my early projects implementing my favorite Microcontroller Microchip PIC 16F84A.
I wanted to make a silent alarm that awakens the human in gentle and quite way.
I wanted to try the vibration motor used in mobile phones.
Using Seven Segment Displays to display the time and alarm. And controlling vibration motor through a controlled by a transistor as a switch.
So here is the circuit to drive it.
Here is my Channel on Youtube:
AeroArduino
Step 1: Components and Circuit
Here is the driver circuit of the vibration motor. This is actually a real time digital clock that can be adjusted to alarm on a specific time of the day.
The circuit is so simple and straight forward.
Here are the required components:
- 1 PIC 16F84A Microcontroller
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, Jumia, Banggood, Aliexpress , eBay
- 1 7447 BCD to 7 Segment Decoder
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, Jumia, Banggood, Aliexpress, eBay
- 4 Seven Segment Displays
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, Jumia, Banggood, Aliexpress, eBay
- 3 5 mm Red LEDs
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, , , Banggood, Aliexpress, eBay
- 1 2N2222 Trasistor
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, Jumia, , Banggood, Aliexpress, eBay
- 1 Relay
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, , , Banggood, Aliexpress, eBay
- 3 Push Buttons
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, , , Banggood, Aliexpress, eBay
- 3 1K Ohm Resistors
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, , Banggood, Aliexpress, eBay
- Virbration Motor
Amazon US, Amazon DE, Amazon FR, Amazon UK, Amazon CA, Amazon ES, Amazon IT,
Souq, Jumia, Banggood, Aliexpress, eBay
Step 2: Software
I must admit it. I’ve been working with my brother on this project from a long time ago. Documentation is not of high quality that I barely remember how we wrote it.
But I still can remember some concepts. So I’ll try to get you to the point.
We’ve tried to make the assembly software run in exactly equal time-consuming branches in all conditions and on all displays.
We’ve managed to make all the 7 Segment Displays have the same brightness by making them illuminated by equal time through the program for the best user visual experience and it actually worked.
The Microcontroller worked as the main time keeper. It sends the BCD codes to the BCD Driver IC then it sends codes to the Seven Segment Displays.
The Microcontroller also controls the relay through a transistor to control the vibration motor to vibrate when the alarm rings.
That’s all. Thank you for reading.
Here are some of my latest books on Amazon.
Learn By Making
Backyard Wind Turbines
Source: PIC16F84 Digital Clock / Silent Alarm
- What is the main purpose of the Silent Alarm project?
The project aims to create a silent alarm that awakens humans gently and quietly. - Which microcontroller is used in this digital clock?
The project uses a Microchip PIC 16F84A microcontroller. - How does the system control the vibration motor?
The vibration motor is controlled by a transistor acting as a switch driven by a relay. - What component converts BCD codes to display signals?
A 7447 BCD to 7 Segment Decoder IC is used to convert codes for the displays. - How did the authors ensure uniform display brightness?
They programmed the microcontroller to illuminate all seven segment displays for an equal amount of time. - Can the alarm time be adjusted?
Yes, the real-time digital clock can be adjusted to alarm at a specific time of the day. - What type of switches are used to set the time?
Three push buttons are used for user interaction and settings.
