-Time plays an important role in our daily activities, more particularly in sectional events or conference arena where there is need for accurate time management. This paper focuses on the development and implementation of an improved digital timer with audio-visual unit using (PIC16F887) microcontroller chip and other electronics component such as LCD, 7-segment display, LED and buzzer as an I/O device. Thus, the need for this device in our daily activities is to monitor the time scheduled for events, updating and alert the audience using an audio-visual approach. The proposed system allows apt time management and avoids time wastage during seminar presentations and the likes. It particularly helps presenters to be time conscious, thus, making them to naturally adjust such that the allotted time is enough to cover up their presentation. The digital timer and alarm system presented herewith is also of advantage to the physically challenged like the deaf and blind in monitoring their sectional activities and to be fully involved about the event situation. The system was designed in different modules, and all were interfaced together with firmware chip to simplify the mechanism's fault diagnoses and fault corrections.
INTRODUCTION
Watches or other timing devices are very important in tracking our daily activities. Timing control and alert system is significant in every aspect of our lives beyond just to tell what time of the day it is. The science of time began when humans started analyzing the patterns of light and darkness which lead to development of the calendar year and a clock based on 60-seconds/minute, 60-minutes/hour and 24hours/day. Clock has been designed in different architecture with functions to determine or solve many problems like day and night period, to control periodic events, to ring a bell every hour or minute, to open doors, run machinery and play music. Presently, humans are controlling actions within the environment in a programmed and predictable manner [1]. Therefore, keeping of time is basic for all control systems.
In every conferences chamber, public room, schools and other convention arena nowadays, timing is a very essential factor considered in the gathering for the coordination and managing of the event. Due to the level of technology nowadays, time is mostly measured electronically using clocks. All clocks measures time but different clocks have varying added functions or importance in their architecture.
This experimental timer and alarm system design in this paper is aimed at time control in regular symposium, in order to solve the usual problems of time delay or overlaps during presentations by sugar coated mouth presenter or people with too many materials, since overtime is an offense to the audience, particularly if there are parallel sessions. Well, this device brings the solution, since it contains timer with light indicator unit (Green, Yellow and Red) and alarm system to tell the presenter the actual time spent logically. Mechanical and electromechanical clocks are being modified and replaced by microcontroller-based digital clocks, this is due to the reduced cost, higher reliability, less power consumption, portability, wide variety of changeable functions by reprogramming the chip and adding new product features. In addition to these, it gives confidence to the experts and student in the area of embedded systems by (learn-while doing) undertaking certain simple in-house experiments with frequent practice on microcontroller-based electronics circuit design and simulation and the replacement of analog devices or components to achieve better performance operation and simple circuit [2].
II.
Several significant papers have been reviewed on the microcontroller-based timing system, which led to this improved digital seminar timer and alarm system development and implementation. The design of a microcontroller-based intelligent digital volume with timer was put forward by the authors in [3]. Their system design is a computer based timer with speaker volume controller, it cannot be used in the conference arena for timing and alarm purposes because of its complexity and difficult to operate since it uses serial communication port and setup. The authors in [4], designed a digital clock using microcontrollerbased system with seven-segment display to display time base on the program coding. The system could not display year, month or day and no alarm system. Also, it became relatively expensive due to the use of external decoder.
Another effort was made on microcontroller-based timing system in [5]. They came up with a 24 segment display for Bangla characters and numerals. Similarly, another effort was made by the authors in [6] towards developing a 10-segment display for Bangla digits, but their segments were not uniform, also, it had some controversy in portraying digits such as “1”, “2”, “3”, and “7” accurately. Furthermore, the work in [7] improved on the work of [5] and [6] by coming up with design of an 11-segment display for Bangla, Arabic and English numerals. This design gives a uniform results and it complements the effort of the previous authors without any segment intersections. Microcontroller based digital Bangla clock and calendar, which display Bangla digits on the 16x2 LCD was put forward by [8]. The author used ATmega8 microcontroller and basic language for the system coding and programming. The clock functions in dual mode of performance, it display digits in both English and Bangla language. No alarm unit incorporating with the system for the message notifications. The electric heating timer based system using Atmel AT89S52 microcontroller was developed by [9]. The system deals with the designing of biomedical related equipment for pain relief based on time dependent heat therapy, which performs count-down operation from 0000 – 9999 minutes with four 7-segment display showing the actual time left for the heat therapy. The system is functioning well in the area of application but lack of monitoring and alarm system when the time elapsed. Author in [10] discuss an approach for managing alarms and diagnosis in an automation management system and integrated information technology milieu, using WBEM/CIM approach technologies. Since, the integration of system management of enterprises and industrial automation become increasingly connected. Therefore, it requires alarms and diagnosis governed system. The shortcoming of the system does not involved timing and logical method of managing industries like light indicator and others.
In this paper, we intend to develop and implement a microcontroller based digital timer and alarm system to enable presenters strictly adhere with time specification and management in conference arena or events. The system consists of three major sections which will be discussed under system design and methodology. The device contains a digital clock, implemented with software codes which allow time to be set and reset, alarm system to alert user when the preset times elapse and indicating light which tell the time conditioning logically.
III.
The Microcontroller based improved digital timer and alarm system was design and implemented with the use of both hardware and software approaches for the design, development and implementation in modular programming. In our design, the software used in the program coding was MikroC Pro for PIC using micro C language. The circuit development was simulated, programmed and demonstrated using Proteus Virtual System Modeling 8.0 (PVSM) and PICKit3 debugger was employed in the process for the real life scenario programming of the microchip. Therefore, the hardware implementation of the microcontroller based improved digital clock and alarm system was carried out and tested on the breadboard before finally soldering on the veroboard.
The hardware design comprises of different module like the system controller unit where (PIC16F887) microcontroller was used for the system programming and performances. The input unit, this unit used combination of (4x4 keypad) for the timing digits input to the system for the processing. Therefore, the output units are divided into three parts: First, the implementation of a 16x2 (LCD) module, which display timing digit pressed for the system operation and time received message display as shown in the figure 9. Secondly, the 7-segment display was programmed to respond to any input time digits for the count-down timer. Thirdly, the (LED) indicator and buzzer, this was designed and arranged serially using time delay to respond to changes in an input timing by shown green light when input timing is fresh, then changed the state when the count-down timer is left with 5 seconds to the end and activate yellow LED, and finally changed the state of LED to RED light when the input timing elapsed. At this stage, the buzzer will be activated immediately and raised alarm to show the accuracy of the system. With all features attached to this system and its performances make it an improved digital clock and alarm system over the existing one as reported in the literature review. This will assists presenters to strictly adhere with time specification and management in the conference arena or events. It will also help the physically challenged people to be fully involved about the present situation of the event and to manage their daily time activities.
In achieving this system, it involves modular implementation of the different units separately before each of the module were linked together to function as a system unit. This give advantages of operating the system easily, and make the fault isolation and fault detection simple. The system was designed to be powered through 5V universal serial bus (USB) port; all components are connected to the common 5V line and grounded. The structural design of an improved digital seminar timer and alarm system is given in Fig. 1.
MCU (PIC16F887) LCD
The PIC 16F887 Microcontroller was used as an
intelligence device, which control and coordinate all the
activities carried out by the system development. This chip
belongs to a mid-range 8 bits architecture and 14
instructional word length of microchip, it consists of 40 pins
(
PIC16F887 has high performance RISC CPU with features of high operating speed; it works on 4-20MHz oscillator/clock input and 200ns instruction cycle [11]. It also contains three timer modules; Timer0, Timer1 and Timer2, where timer0 module was used for the timing in this work. The OPTION register is a readable and writable register which contains various bits to configure the Timer0/WDT prescaler, External INT interrupt, Timer0 and Weak pull-ups resistor on PORTB.
In this work, 4x4 matrix keypad was used as a data input device for the system timing or logical configuration of the system operation. In the process of connection, the four button pins along the rows are connected with the four buttons pins across the column to reduce the input connection switches to 8 pins, which are directly connected to the microcontroller of the system. The four button pins along the column are configure to be inputs and grounded (GND), while all the four buttons across the rows are configure to be output as shown in the simulation circuit design in figure 9. The four input pins along the column are connected to the Port D (RD0-RD3) of the microcontroller and grounded, while the other output four pins across the row of the button are connected to the Port D (RD4-RD7) with 10k resistor for each connection pins. If one of the sixteen buttons is pressed, it connects a pair of pins together. This feature helps in detecting which button is pressed. The internal and external architecture of the keypad connection was shown in the figure 4 and figure 5 respectively.
A B C D 1 2 3 4
The first output device used in this system was 16x2
LCD (HD44780) parallel interface chipset, 16 pins
connection, easy to configure and program which commonly
used in the various simple and complex embedded systems
to exhibit output information. LCD (Liquid Crystal Display)
is an electronic module use to display alphanumeric data on
the screen, a 16x2 LCD denotes 16 columns and 2 rows
capable of displaying 16 characters per line/row and there
are two (
A seven segment display is the most common basic
electronic display device capable to demonstrate digits from
0-9 and beyond in a clearly digital form. It can be used in
many applications of electronics and embedded system
devices to display numeric information like in the digital
clocks, radio, microwave ovens, electronic meters etc. The
arrangement are laid out as a squared-off shown in the in
Figure 7, every LED is assigned a name from 'a' to 'h' and is
identified by its name. Seven LEDs 'a' to 'g' are used to
display the numerals while 'h' is used to display the
dot/decimal [12]. Common cathode type of seven-segment
display was used in this design, the pin 11 and 12 of the
device was connected to the Port A, pin (
In CC configuration, the negative terminals of all LEDs are connected to the common pins (low voltage) and common pin is connected to ground to glow a particular LED when its corresponding pin is given high logic to display a number.
The application of (LED) in this development system
was divided into two functions. First, it serves as an indicator
light, and also as control and monitoring timing system.
Three different color of LED was used for the control and
monitoring system (Green, Yellow and Red) which indicate
time begins, ready to stop and stop respectively. The LED
was connected to port E, pin (
From Figure 7, using voltage divider rule withVcc 9V , where RD is the resistance of the green LED, R1 is obtained thus:
VR1
Vcc R1
R1 RD R1Vcc VR1 (R1 RD ) R1 (Vcc VR1 ) VR1 RD R 1
VR R
1 D Vcc VR1
A buzzer is an audio signaling device, which may be mechanical, electro-mechanical, or piezoelectric. The wide areas of application of buzzers include: alarm devices like clock, timers and confirmation of user input such as a mouse click or keystroke [14]. The buzzer is connected with NPN transistor, wired with the third LED that indicating stop and connected to the port E, pin 10 of microcontroller. This device was configured and programmed to sounds whenever the preset time interval has elapsed or when red light is activated (STOP). Figure 8 depicts the wiring method of buzzer in our design. V.
SYSTEM FLOWCHART Therefore, RB which is the base resistor of the transistor is obtained as:
RB
IB VB VBE 10 0.7
The development and implementation of microcontrollerbased digital timer and alarm system was design and tested to ensure workability and reliability of its performance. The system can be programmed for timing purposes by connecting it to the laptop through a USB port for powerdriven, and simply press the ‘*’ key on the keypad to prepare the system for data input or timing code. Then press the ON/OFF key to enter the countdown time or event time. For the proper interaction, the digits pressed/entered are displayed on the LCD, when the user is done with timing range, the ‘#’ key is pressed and the system checks the time inputs. If it is a valid time, the message display on the LCD “TIME RECEIVED” or else display “INVALID TIME”. This required a user to enter a valid time.
But if a valid time is entered, the time will be shown on the “7-Segment Display”, activating the green light and the time will start counting. When countdown time reaches 90% of the stipulated time, the Green LED goes off and activates yellow LED. Once the countdown time expired, the yellow LED goes off and activates Red LED as well as buzzer activated to sound in support of expiring time set. Start Input Time Is time valid?
Yes Count down on green
LED Has 90% of time elapsed?
Yes Put ON Yellow LED and count down Time Up?
Yes Put ON Red LED,
Sound Alarm
Stop
No
No
The design is an embedded microcontroller-based system, with LCD, LED, seven segment display, keypad, buzzer and others electronic components. It is divided into hardware and software parts. In the software part, the MicroC program on the controller core can initialize the parameters, configure the simulation and communicate with the hardware model.
If the time set for the system is 5 minutes in the clock, green light is activated and glow indicate the beginning of time, and counter will count by decreasing timer till it gets to 1 minute to the end of timing, after which the yellow LED will come up to tell about the timing. Finally, when it counts to exactly 5 minutes of the total timing, the red lights will be activate and turn ON, at the same time it triggers the alarm system; the buzzer immediately comes up and interrupts the presenter logically. Details implementation and testing of the digital timer and alarm system are shown in the figure 11. +5v
RV1 % 4 10k
LCD1 LM016L
VSS VDD VEE SR RW E 0D 1D 2D 3D 4D 5D 6D 7D 1 2 3 4 5 6 7 8 9 01 11 12 13 14 +5v +5v +5v
+5v R5 2k
Q4 v5+
R1 20k
R9 330 D1
LED-GREEN U1
COMPARATIVE STUDY WITH SIMILAR WORK IN
LITERATURE REVIEW
microcontroller based improved digital timer and alarm system put forward in this paper was evaluate by comparing with the existing similar work in the literature from the perspective of the components used, performances and their area of applications.
S/N
Victor et al. (2012) Mizanur et al. (2012) Design and development of microcontroller based digital bangle clock Microcontroller based intelligent digital volume controller with timer Microcontroller and LCD based digital Bangla Clock and calendar Arushi & Sakshi (2016)
This work presents the development and implementation of microcontroller-based improved digital timer and alarm system. It is applicable for monitoring time preset, avoid premature abortive time measures and enhance effective time usage by updating and alerting audience in the conference arena. The completed work was tested to ensure that the required task of timing, alerting and interrupting were all well done. This was established to improve on learning idea, enhanced research and technological improvement on embedded system design and development using microcontroller chip. The simulation, bread boarding, soldering and the final packaging of the device was also presented. Further research work may include using other
COMPARATIVE STUDY WITH SIMILAR WORK IN THE
REVIEW LITERATURE.
The author employed ATmega 32 microcontroller and 7segment display in their design to show the digits in both English and Bangla languages, but no LCD and alarm system The system was designed to control music system and volume level using Atmel 8051 microcontroller, 7segment display and others. Based on their focus, alarm system, LCD is not considered.
Atmel 8051 microcontroller, LCD, 7segment display was used in their design to display time and calendar in Banglar language. The system is not capable of alerting.
The authors used Atmel 8051 microcontroller, 7segment display and heating element for their design as time totalizer for dependent heat therapy. No alarm system inclusive in the designed should in case of monitoring. firmware technology like System-on-Chip (SoC), complex programmable logic device (CPLD) or field programmable gate array (FPGA), Arduino microcontroller etc to make the device efficient, portable compact, and more functions. from [12] “7-Segment Display”, http://www.engineersgarage.com/ segment-display.
retrieve from electronic-components/7[14] "Buzzer - definition of buzzer by The Free Dictionary".
Retrieved May 2015.