The application of microprocessors in electronic circuits can not only be done on one or two circuits. But this can be applied to various electronic circuits, one example is its application to the lighting system of the stack lamp of the building. In this discussion, we take the RSG-GAS building as an example. The lighting system of the RSG-GAS building stack lamp is one of the supporting systems used to provide lighting to the RSG-GAS building stack which is located above the RSG-GAS building with a height of ± 30 m from the ground. The types of disturbances that often occur in the lighting system of the RSG-GAS building stack include:
- The lights are not on.
- The Light Depending Resistor (LDR) and its electronic circuit were damaged so that the RSG-GAS building stack lighting system did not turn on.
- The method used to complete this design consists of five stages, namely making a system model, making a power supply circuit, making an RS232 Serial Port Interface circuit, making an AT89C51 microcontroller circuit, making a program listing, and assembly and function testing.
One of the efforts that can be made to overcome the above matters is to design a lighting system for RSG-GAS building stack lamps based on a microcontroller using main components and supporting components, including:
- LDR sensor as a system switch.
- Eight AC relays as load sensors and DC relays as light switches.
- As well as a Serial Port Interface circuit (RS232 converter) to connect the system (hardware) with the program (software) on the PC.
The design of this system prioritizes safety aspects and its use can last longer so that the results of this design are expected to function better and replace the previous lighting system.
A. Microcontroller
Microcontroller is one of the electronic components that contains a microprocessor circuit, memory (RAM/ROM) and I/O, the circuit is in the chip level or commonly called a single chip microcomputer. In the microcontroller there are already microprocessor components with interconnected internal buses. These components are RAM, ROM, timer, parallel and serial I/O components, and interrupt controller. Microcontroller is also a digital integrated circuit with large-scale LSI (Large Scale Integration) or very large VLSI (Very Large Scale Integration) integration with very high complexity and has the ability as a central processing unit CPU (Central Processing Unit).
One of the advantages of a microcontroller is that it has an interrupt system. As a control adjustment device, the microcontroller is often referred to as raising the response of external enthusiasm (interrupt) in real time. The device must perform a fast switching relationship, delaying one process when there is another execution response. The type of microcontroller that has the advantages as mentioned above is the AT89C51 microcontroller.
B. Relay
A relay is a switch controlled by current. The relay will work if there is an electrical signal input (voltage/current). Relay components include a coil, an iron core and an anchor. The coil that is supplied with electric current produces a magnetic field in the iron core, so that the anchor activates the relay contacts after the anchor is attracted to the iron core. The construction of the relay is as shown in Figure 1.
Figure 1. Relay Construction
The type of relay based on its working principle consists of 2 types, the first is Normally Open (NO) is a relay whose contacts are open when there is no current passing through the coil and closed when there is current and the second type is Normally Closed is a relay whose contacts are closed when there is no current passing through the coil and open when there is current. The advantage of using a relay generally lies in its switching settings, so that there is isolation between the low power supply circuit and the high load power supply that will be disconnected/connected. Relay losses generally occur due to the relatively slow response time when ON/OFF.
C. Design and Construction Method
Methods for completing this design include:
- System modeling
- Making a power supply circuit
- Creating an RS232 Serial Port Interface circuit
- Making the AT89C51 microcontroller circuit
- Creating a program listing
1. System Model Creation
Figure 2. Block Diagram of the Whole System Circuit Model
The power supply for the stack lamp lighting system circuit comes from PLN, namely 380 Volts (phase-phase) or 220 Volts (phase-neutral) with a frequency of 50 Hz and a non-interruptible power supply source (UPS). The working principle of this uninterruptible power supply system is that under normal conditions it supplies consumers while charging the battery. If the main PLN power supply is disrupted, the stack lamp lighting system is obtained from the UPS-AC that is already available in the RSG - GAS building.
2. Making a Power Supply Circuit
The components used in the power supply circuit consist of a transformer, rectifier, filter circuit, and regulator IC. The wave rectifier circuit used is a full-wave rectifier circuit using 4 diodes known as a diode bridge. The output of the rectifier circuit is a rectified sinusoidal wave as shown in Figure 3.
Figure 3. Power Supply Circuit
The AC voltage rectifier uses 4 diodes or is called a bridge diode with a full rectifier system, while to reduce ripple using 1000 μF (C1), 220 μF (C2), and 100 μF (C3) capacitors and the LM7805 IC as a regulator. On the other hand, capacitors C2 and C3 also function as ripple filters that may still occur, especially at high frequencies. The use of a transformer here functions as a voltage reducer. The use of a relay driver in this system design is to activate load 1 and load 2. In the relay circuit there is a transistor that functions as a switch. This transistor gets voltage from the microcontroller and will activate the relay. The collector voltage that drives the relay will not exist if there is no current to the base. The relay driver circuit is shown in Figure 4.
Figure 4. Relay Driver Circuit
The working principle of a transistor as a switch in general is that if there is no current or voltage passing through the base, the transistor does not work in the active region, so there is no emitter current. When there is voltage or current passing through the base, the transistor will work and current flows through the emitter which will activate the relay. Thus, if V1 is given a voltage level of "1", the transistor will work so that the relay will be active (ON), while if V1 is given a voltage level of "0", the transistor does not work so that the relay is not active (OFF).
3. Making an RS232 Serial Port Interface Circuit
To connect the stack lighting system circuit with a PC is through the RS232 serial port which is generally available on every PC. However, the RS232 standard has a different level with the TTL digital data format. Therefore, to connect the device to a PC, a converter circuit is needed that will adjust the TTL data to RS232 and vice versa. The converter circuit is shown in Figure 5.
Figure 5. RS232 Interface Circuit
4. Making the AT89C51 Microcontroller Circuit
This circuit is the center of data processing and device control. In this microcontroller circuit, there are two ports used to accommodate input or output data and are directly connected by the circuits. This circuit consists of an AT89C51 microcontroller, a 11.0592 MHz Crystal oscillator that functions to generate internal pulses, 2 33 pF capacitors that function to stabilize the frequency, a 10 μF capacitor and a 100 kΩ resistor that functions as a reset circuit before the program on the microcontroller is executed. The AT89C51 microcontroller circuit is shown in Figure 6.
Figure 6. AT89C51 Microcontroller Circuit
Data from the ADC enters port 0 (pin 32 - pin 39) then the data is processed and output to port 2 (pin 21 - pin 28). For port 1 (pin 0 - pin 7) is the input from the keypad, the data is processed and output back to port 2 then displayed with BCD to seven segment. So that the microcontroller can execute the program from the beginning of the program (address 00H) then the microcontroller will be reset automatically when the power supply is first turned on where for this automatic reset is done by C3 and R1 (Power On Reset). In this way the reset will take place automatically, however manual reset is still needed for certain circumstances such as to restart the program from the beginning without having to turn off the power supply. The working principle of this automatic reset is the process of charging and discharging C3 where the reset pin requires high logic. When the power supply is turned on, C3 starts to be charged while there is no voltage on the reset pin. After C3 is full, the voltage from C3 will ignite the reset pin high so that a reset occurs. When the power supply is turned off, C3 will be discharged through R1 so that when the power supply is turned back on, the charging process will occur again so that a reset occurs. The specifications of the AT89C51 microcontroller used are shown in Table 1.
Table 1. AT89C51 Microcontroller Specifications
5. Creating a Program Listing
The software used in this system uses the assembler language, Borland Delphi and Java programming languages. Borland Delphi is applied for the monitoring display and Java as an application that can send data to the database. The results obtained in this study include flowcharts, program listings, software, and hardware. The resulting flowchart consists of a flowchart for operating the tool, checking the lights and replacing the stack lights.
D. Assembly Results
The results of assembling the RSG-GAS building stack lighting system circuit, as shown in Figure 10.
Figure 12 shows the monitoring of the stack lighting system on the PC monitor consisting of the position of the lights in the North, East, South and West. Each of these positions has 2 lights that light up alternately (flipflop). The light indicators are divided into 2 types, namely Red and Green. The indicator light on the PC monitor lights up Green indicating that the light at the end of the stack is on, but if there is a stack light that is not on in one of these positions, the indicator light on the PC monitor will light up Red. All events of the on and off conditions will be stored in memory so that the nurse knows when the light is not on. The display of all light condition events will be easily known by the nurse looking at the display provided on the PC.
The initial step in operating the lighting system design is to connect all the elements of the tool and connect the tool to the computer on the RS232 connection (keyboard port), pressing the system power button. After the tool is on, the light sensor responds to the light intensity around it to then flow/disconnect the voltage and current from the PLN, then reduce the light intensity ≤ 30 lux to activate the system, power supply, 8 (eight) DC relays that will turn on 8 (eight) main lights, so that all the main lights are on properly.
If all the lights are not on, then the LDR sensor circuit must be checked to ensure the light received is ≥ 30 lux, or the LDR sensor is damaged. To condition the function of the AC relay connected to the main light, the main light must be off or disconnected, then the AC relay will automatically provide information on the condition of the main light to the microcontroller and give a command to the DC relay connected to the second light to activate the second light, if the second light is on properly, then the lighting system design can be said to be operating properly, while to condition the function of the AC relay connected to the second light, the second light must be off or disconnected, then the AC relay will provide information to the microcontroller to then send data to the PC monitor. The display on the PC monitor will show the condition of the lights continuously.
Conclusion
Based on the results of the functional tests that have been carried out, it can be concluded that:
- The design and construction of the RSG-GAS reactor building stack lighting system can function well so that it is expected to be used as an alternative to replace lighting system equipment that has been operating for a long time and the realization of its manufacture can be carried out in the electrical workshop at RSG-GAS.
- One of the capabilities of the design and construction of the RSG-GAS reactor building stack lighting system is that it can provide continuous and accurate information on the condition of the stack lights which can be monitored via the RSG-GAS building Main Control Room (RKU).
Bibliography
- Aninomous, Interatom, GmBH, “Electrical Safety Analysis Report of MPR-30”.
- Paulus Andi Nalwan, “Practical Guide to AT89C51 Microcontroller Interface and Programming Techniques”, Publisher PT Elex Media Komputindo Grup Gramedia, Jakarta.
- Owen Bishop, “Electronics Basics”, Erlangga Publisher, Jakarta
- Maxim +5V-Powered, Multi-Channel RS-232 Drivers/Receivers. Accessed from http://www.maxim-ic.com
- Teguh Sulistyo, 2006, "Design and Construction of RSG-GAS Reactor Core Lighting System", Seminar on Research and Management of Nuclear Equipment in Yogyakarta.
Microprocessor Applications in Robots
Robots are one of the microprocessor-based systems that are often used for very broad applications, for example, bolt-installing or car body painting robots in the manufacturing industry, fire source trackers in firefighting teams, material sample seekers in research on the moon, children's toys, and so on.
Figure 9.10: Robots in the Bodywork Industry
There are various types, depending on several factors, including:
- the number or types of tasks it can perform,
- the control system used,
- level of intelligence (able to learn, make decisions, carry out certain actions after experiencing learning, for example answering questions, etc.).
Try to point out one of the tools or toys around you that is a robot.
Figure 9.11: Basic Robot Control
The main tasks in robot control include:
- Adjustment of rotation and position of the shaft (speed and location)
- Interpolation path (e.g. linear or circular)
- Coordinate transformations (e.g. space coordinates in a joint)
- Communication with sensing devices, operators and programming tools
- Programming (e.g. saving and editing programs).
Figure 9.12: Coordinate Transformation
Among these jobs, coordinate transformation and interpolation path setting are jobs that require very fast calculation processes and logical decision making, because the results of these calculations are often continued or connected with the next calculation or compared with a value, so that the right path and smooth movement are obtained.