Now I have a lot of electric lighting control devices remotely using the remote to the media or infrared waves, but still rare equipment that can control the electric lights when they're at a distance by using the GSM provider facilities. So the design of an electric lamp control remote is trying to use SMS facility on mobile phones, which are expected to control and monitor electric light equipment remotely from any area of origin is still affordable GSM operator signal.

Hardware Box Diagram

Lighting control system with this SMS media, designed based on AT89S51 microcontroller based. Figure shows the block diagram of this instrument.

Block diagram of the system

Diagram shown in Fig overall system box. HP Siemens M35 is used as a SMS Gateway. HP with a microcontroller connected by using a data cable using RS232 serial communication. Types of communication used is UART model.

Microcontroller has a role as a base system. Microcontroller will read and communicate with HP, then control the light with the help of relay drivers, and to read sensors that have passed a comparator.

Drivers installed aims to control the lamp voltage acting on AC/220V. This is absolutely necessary because the microcontroller only works with TTL voltage levels and CMOS, and is unable to directly control the lights.

A phototransistor sensors are used to change the light conditions in the quantity of electricity. In order for an analog sensor that is able to be read by the microcontroller which is digital, so need to install a comparator. These comparators compare the charge for entering the sensor pin () op-amp with a reference voltage at pin (-) op-amp as dark or light and convert it into digital logic on its output pin. While the gate 74LS14 not have the ability to trigger a pulse on the data input and output of the IC sheet is already standard TTL that can be directly connected with microcontroller. Gate 74LS14 not also be used to reverse the situation so that the input voltage at high input value then the output will be low.

Microcontroller and mobile communication

To communicate between the microcontroller and mobile communication facilities required by the model serial UART speed to 19200bps HP Siemens M35 type. This speed will vary depending on the type of HP used. The voltage used is RS232. Meanwhile microcontroller only provides serial communication facilities UART TX pin, and Rx with RS232 voltage levels. This requires an adapter system that can change the TTL voltage levels to RS232 levels.

At HP Siemens M35 connector is for communicating with external devices. Usually this connector can be accessed by serial data cable. Generally, the data cable is equipped with a RS232 converter to the microcontroller requires an additional tool that the converter modules from TTL to RS232. Scheme presented in Fig serial communication circuit RS232.

RS232 communication

To meet the required standard RS232 communication converter IC MAX232. IC is manufactured by Maxim dallas semiconductor. In this IC system was equipped with a RS232 adapter that connects to live T1IN with pin pin TXD on P3.1 of microcontroller, and connects with R1IN pin RXD pin on P3.0 of the microcontroller.

On the HP before entering the terminal must be first converted into voltage levels that can be accessed by a Hand Phone. Generally, this conversion is automatically done by the data cable from Hand Phone is. Model data cable connection to the HP Siemens M35 described in Figure

Model data cable Hand Phone Siemens M35

Model presented in Figure data cable connection is compatible with the PC. Presented in Figure connections at HP Siemens M35. On this connector there are 2 pins as lines of communication. In connection Hand Phone Siemens M35, which pins should be connected in accordance with the function of each terminal. The functions of each device are presented in table

Fig Terminal port on the HP Siemens M35

Table Function HP Siemens M35 terminal

2SELF SERVICERecognition / Battery ChargerIn/Out
3LOADCharging VoltageIn
5DATA OUTData SendOut
6DATA INData ReceiveIn
7Z_CLKRecognition / Control Accesoris
8Z_DATARecognition / Control Accesoris
9MICGGround for MicrophoneIn
10MICMicrophone input
11AUDLoudspeaker outputOut
12AUDGGround for Loudspeaker

Sensor dan Komparator

In the SMS application system to control the lamp is close the loop. It needs to be installed for the light sensor to monitor the light produced by light. In addition, the light sensor will also provide notification of interruptions or signal to the microcontroller.

This sensor uses the main components phototransistor. Phototransistor is a light sensitive component that works as a transistor works. Phototransistor output amplifier strengthened by the comparison or commonly referred to as the comparator. Comparator output is inserted into a Schmitt trigger input before accessible to the microcontroller. The purpose of the Schmitt trigger is installed, so that the output voltage level in accordance with TTL voltage levels. Images presented image sensor light.

Picture Sensor Light

The workings of this series is if exposed to light the phototransistor will be closed or small bertahanan. So that at the foot of the comparator non-inverting input will be of low value or lower than the inverting input voltage. So that the comparator output voltage will be low. This voltage will then be a logic behind higher by inverting Schmitt trigger that will be a 74LS14 logic 1. If not exposed to light the phototransistor resistance value would be high, or a transistor circuit load. Inverting input so that the value will be higher than non-inverting input. This will cause the comparator output high and then reversed by a 74LS14 Schmitt trigger is low.

So when exposed to light, the sensor output will be high, and if not exposed to the light sensor output will be low. Potentiometer R2 serves to adjust the voltage of comparison or reference voltage.

Relay Driver and Load

Microcontroller can issue 0V and 5V voltage. But in reality this voltage can not be used directly to drive the load. This is because the current can pass by the legs of a very small microcontroller. It needs to be installed for devices that can strengthen the flow, so it can be used to move the load. This tool usually called by the driver.

Driver circuit usually consists of power transistors. But for the load voltage of 220V AC switches need to install electronic device that relays. Ironically microcontroller relays are not able to move directly, it needs to be installed for the transistor. In Figure presented a driver for AC 220V lamp with microcontroller control.

Driver Picture lights

In Figure 3.7 driver circuit, the transistor used to drive the transistor FCS9012 TIP 31. This is done because the current from the microcontroller is too small. Meanwhile transistor TIP 31 is used to drive relays. The workings of this series is, if given a low or 0V logic of microcontroller port, then the T1 PNP will work or connected to the base of the NPN T2 will berlogika high, so the T2 NPN will work or connect. So if T2 is connected to a relay 12 VDC supply voltage. After the relay ON, then at the point of NO (Normaly open) will close and will be connected to phase 220 VAC and a current will flow into the lamp so the lamp 1 lights 1.

Conversely if the microcontroller port issue logic high (1), this situation would make T1 PNP will not work because the PNP transistor is active low, so no current flows into the pin base NPN T2 and not make the relay work. With this output relay will be connected to NC (Normally Close), so that the lamp will not light 1 as not connected with the voltage phase 220 VAC. Resistors 1 and 2 of this resistor is limiting the base current for transistors, resistors besanya values can be sought by way of a mathematical way to see the value of each HFE transistor from the data sheet.
Bookmark and Share
My Zimbio
> TopOfBlogs .sg   TopOfBlogs