Internet of Things Based Control and Monitoring LCD Projector for Smart Class Room Concept

Abstrak Konsep Smart Class Room membutuhkan teknologi modern untuk mengontrol dan memonitor perangkat Liquid Cristal Display Projector. Desain teknologi ini dapat dicapai dengan menerapkan Internet of Things. LCD Projector dapat dikontrol secara remote melalui aplikasi mobile berbasiskan android. Research and Development merupakan metode yang tepat digunakan untuk menghasilkan prototipe. Hasil implementasi sistem memperlihatkan remote control melalui jaringan internet menggunakan firebase database realtime dapat dicapai dalam durasi waktu 3 detik. Jarak antara LCD Projector dengan perangkat sistem tertanam dapat berkomunikasi dengan baik hingga 2 meter menggunakan sensor Infra merah. Perubahan temperatur dan ambient intensitas cahaya dapat terdeteksi baik dalam waktu pengukuran 500mS. Deteksi arus memperlihatkan 4 mode status LCD : ON, OFF-Fan On, Stand by dan Off. Kata kunci: Smart Class Room, Internet of Things, Monitoring LCD, Deteksi Arus, Aplikasi Mobile Abstract The Smart Class Room concept requires modern technology to control and monitor Liquid Crystal Display Projector devices. This technology can be created by implementing the Internet of Things. The LCD Projector can be controlled remotely via an android-based mobile application. Research and Development is the right method to produce prototypes. The results of the implementation of the system show that remote control via the internet using a realtime firebase database can be achieved in 3 seconds. The distance between the LCD Projector and the embedded system device can communicate well up to 2 meters using the Infrared sensor. Changes in Temperature and Ambient Light intensity can be detected within 500mS measurement time. Current detection shows 4 LCD status modes: ON, OFF-Fan On, Stand by and Off.


1.
Introduction Smart classroom is a modernization concept in the world of education. In Indonesia, the smart classroom concept has begun to be developed. The smart classroom concept [1] requires automation of classroom support devices to optimize the teaching and learning process, reduce device maintenance costs and energy efficiency using internet of things technology approach [2].
Classroom technology shifted over time, starting with the blackboard and the use of chalk in the 1890s, shifting to whiteboards with marker ink, the use of overhead projectors (OHP), desktop computers and Liquid Crystal Display Projectors (LCD projectors), interactive whiteboards, smart phones and tablets [3] [4]. Through the application of this technology, the classroom teaching model has changed from the "blackboard and chalk" model to the "computer and LCD" model [5][6] [7]. Frequent use of LCD projectors results in increased damage to this device. The most common cause is user error.
People have implemented several strategies to reduce the operational failure rate on these devices. One of them is by permanently installing the LCD Projector in the classroom and attaching the device SOP. This method is still not effective. Permanently installed LCD without being equipped with a solid remote control causes permanent damage to the LCD Projector because the user uses the beam to operate the LCD Projector [8], so it is necessary to make a control mechanism and operational monitoring of the LCD Projector device. Internet of things technology can be used as a solution to design a control and monitoring system for LCD projector devices so that it can reduce the failure rate due to operational procedure errors.

Research Method / Proposed Method
The research method uses a Research and Development approach to produce a product. The object of research is the Control and Monitoring of LCD Projector Based on the Internet of Things for the Smart Class Concept. This study aims to determine the success rate of system product design using a simple internet of things architectural diagram approach as shown in Figure 1. If a problem is found in the system, whether it is due to user error, methods/procedures, communication systems, or measurement techniques, then the analysis step can be carried out in the brainstorming session.

Mobile Application
Embedded System Application

Literature Study
Liquid Cristal Display Projector (LCD Projector) works based on the refraction of light by LCD panels. In order to monitor LCD devices, we need to know the components of the LCD Projector technical specifications [9]. The first component is light intensity. The light intensity determines the brightness level of the LCD. Generally the brightness level ranges from 3000 to 4000 Ansi lumens [10]. The second component is the working temperature of the LCD projector. Working temperature Range from 40 to 55°C. The third is work power. The working power of the LCD Projector consists of : High (±269 Watt), Standard (±218 Watt), Low (±186 Watt) and on standby mode (±0.5Watt) [11]. And the fourth component is the remote LCD projector device. By using this remote device, a reengineering process can be carried out to obtain a remote communication protocol format between the remote device and the LCD Projector. Based on it, the LCD Projector Monitoring Status in On, Off and in Standby mode can be known.

Result and Discussion 4.1 System Overview
The LCD projector control and monitoring system was developed to create a smart classroom concept. Users can monitor and control the LCD Projector through an application on a smartphone as shown in Figure 2. LCD status updates are sent in real time when the smartphone system and application are connected via the internet. Transfer data from smartphone applications and embedded system applications using realtime firebase database services. This service allows two-way communication. The embedded system performs data acquisition from sensor readings and sends it to the firebase realtime database continuously so that users via smartphones can monitor the status of the LCD. Users can use the remote

Results of Hardware System Design and Implementation
The embedded system digital signal receiver circuit ( Figure 3) is used in the reengineering process. The analog remote control signal emitted by a product of a certain type and brand (based on an infrared signal) is captured for further translation into a string of binary numbers that have a specific meaning. The data obtained is then translated and retransmitted using a series of infrared signal senders ( Figure 5). Tests on the reengineering process that have been carried out have resulted in mapping the digital number form of the LCD Projector product with the PJ-xx Serial Number. The signal code in hexa decimal form obtained from the raw data of the signal receiving circuit is used as input data and transmitted back to control the LCD projector using a series of embedded LCD control systems. The LCD control embedded system is a set of electronic circuits used to control and monitor the LCD. This circuit mainly consists of an ESP 8266 microcontroller as a signal processor that supports internet network communication via a wifi connection. The temperature sensor uses the DHT11 Series with a measuring sensitivity of 1 °C. The light intensity sensor uses the BH1750, 16 bit serial output module. The BH1750 supports I2C BUS interface with a filter that reduces noise at a frequency of 50/60HZ. Calibration is carried out to determine the error rate of sensor measurement readings by comparing the sensor measurement results with a light intensity measuring instrument. By comparing the measurement results as shown in Table 1, it can be seen that the standard deviation value is 0.98 and the standard error is 0.28.

Results of Software Design and Implementation
Software applications are developed in two different application services. The first application was developed for end users via a mobile application as shown in Figure 8a. The application runs on the Android operating system, developed using the Java programming language with the Android Studio IDE. The appearance of the application interface design follows the actual LCD remote device model. This makes the application easy to use due to the experience of users who are used to using remote devices that are already available. Firebase Database Realtime as one of the two-way data interconnect API's is used as a two-way data transmission service. This service allows real-time data updates (Figure 8b). Embedded system software applications are built using the C programming language, which runs on the Real-time Operating System (RTOS) Software development Kit kernel. The service model uses a time scheduler for sensor measurement task management as shown in Figure 9. Main Program is in a state of listener receive data from firebase update. The interrupt service routine timer flags the sensor to perform measurements and perform measurement data acquisition periodically. Sensor measurement results are sent to Firebase Dabase Realtime periodically within 1 minute (Example in Figure 10). When the Listener receives a remote control command via the firebase updater receive data the app prioritizes the task and delays sensor measurement. The embedded system application provides a response in the form of data updates while updating sensor measurement data in the database.

System Integration Results
System integration ( Figure 11) testing is conducted to determine the overall system performance. The remote control of the embedded system can work well with a test distance of 2 meters. The system is capable of transmitting updated measurement data from the mobile application to the embedded system application and vice versa within a test time period of 3 seconds so that some features that require execution time of less than 3 seconds cannot run properly. The change in the ambient light intensity value when the LCD is first activated takes 83 seconds from an ambient value of 28 lux to stabilize at an intensity of 320 lux ( Figure 12). Changes in the intensity value are strongly influenced by the measurement distance from the light source and the light intensity of the environment. The temperature increased from the measured environmental temperature of 28 degrees Celsius with a peak value of 51 degrees Celsius with a time of 4 minutes 7 seconds, and decreased to the optimal working temperature of the LCD Projector 45.2 degrees Celsius (Figure13a). Figure 13b shows that the LCD projector temperature has decreased. A very sharp decrease occurs when an active LCD projector fan cools the LCD which enters the OFF state. At the optimum temperature of 35 degrees Celsius the LCD FAN stops cooling the LCD and the current to the LCD can be cut off. The results of the observation of current detection show a change in the value of the microcontroller ADC voltage reading. At the position of the system detects the peak to peak amplitude showing results from 0 volts to 1 volt. In the valley, there is a signal that is cut off as a result of the midpoint offset value being at a lower value. The peak value is at 1 Volt. When the LCD Projector is turned off, the LCD Projector current signal detection changes where the working current from the fan is controlled on-off by the system. From the results of the detection of temperature changes, it can be seen that the fan is active from off mode within 1 minute. Figure 14.a shows the results of current detection when the LCD Projector is on. It appears that a signal with a frequency of 50 HZ is detected with a peak value of 1 Volt and a valley value of 0.1 volts. This is the offset of the maximum value of the current detected using the ADC reading. When the LCD Projector OFF status (Figure 14. b) it appears that there is a difference in wave amplitude. This is because the fan control on the LCD projector is still active to cool the bulb. This signal change is still well detected. After the LCD Projector Fan Off, the LCD Projector enters Stand-by status (Figure 14. c). In Stand-by condition, the LCD projector is detected to still consume current with peak wave amplitude at 0.53 Volt and 0.47 Volt at valley wave. In this condition the LCD Projector current can be safely disconnected from the voltage source using a relay (Figure 14. d).

Figure 14. Current LCD Detection
In standby condition, the LCD still consumes power, so the source current needs to be disconnected. Current observations take about 1 hour 10 minutes to cool the LCD projector at room temperature.

Conclusion
The results of the system implementation have met the system design requirements. The LCD Projector Control System using embedded system devices can be carried out up to a distance of 2 meters. The remote controller and system can update data remotely within 3 seconds via the internet. The response time to changes in temperature and environmental light intensity looks very good in the test time duration of 500mS. Current detection to determine LCD