Control Circuit Project Implementation - Assignment Example

?PROJECT IMPLEMENTATION Project implementation This chapter will address and contain the following information; Blockdiagram, Step by step explanation of the different parts of the circuit. The combination of the different parts into one single project, PCB design will cover issues of layout, track information, and the circuit’s EMI. The fault finding process of both customer and manufacturer will be addressed in the chapter with absolute clarity. Finally, the bill of materials and any other specific requirements will be addressed. To expound understanding of the system, the RF module will be employed covering the details of encoder and decoder. The main function of the encoders and decoders is to convert parallel data to series data. Design of the control circuit The function of the control circuit will be to give an alarm to indicate the departure of the child. The communication process that will be employed is the RF communication because it is the most accepted and affordable cost solution. In the RF module, both transmitter and receiver pairs are essential because the communication uses the principle of serial communication. The module of operation demands a component that converts the n-bit data to serial data. The RF module can, therefore, employ Serial encoders or decoders (HT12D and HT12E) to convert the data or task. RF communication block diagram The block diagram of the RF communication illustrated above employs the encoders/decoders that are TTL compatible. Therefore, the input levels are depicted in a TTL Logic level. To solve the problem, the TTL input must be changed into serial data input. To have a serial data input, an encoder must be used because; it can be read directly by the RF transmitter performing the amplitude Key shifting (ASK) modulation, and further transmitting the data via antenna. At the receiving end, modulated signal by the antenna is received; the RF Receiver carries out the filtering, demodulation and processing of the transmitted data. The data obtained at the end is a serial data that is converted to a TLL level logic data. The RF Module The module comprises of an RF receiver and transmitter. The two operate at a frequency of 434MHz. The transmitter obtains serial data from the encoder and transmits it using a wireless platform provided by the antenna attached to the pin 4 (data). The transmission speeds are between 1Kbps and 10Kbps. The RF receiver operated at the same frequency as the transmitter to obtain the data transmitted. In most cases, the RF module is used beside coupled with a pair of encoder HT12E and Decoder HT12D. The encoder is useful in encoding parallel data for transmission while the receiver send the required signal to the decoder for decoding. Features Range frequency of the TX: 433MHz Supply voltage of the TX: 3V ~ 6V Coverage in open space (standard Conditions): 100 Meters Receiver Frequency (RX): 433 MHz Operating voltage of RX: 5V Supply current of the RX: 3.5 mA RX IF Frequency: 1MHz Low Power consumption Easy Application HT12E and HT12D The decoder (HT12D) is ICs comprising a series of CMOS for remote control applications. The IC is paired with an encoder HT12E with the HT12D main role is the conversion of the serial input to parallel output. The HT12D decodes the serial addresses and data that are received by the RF receiver, which in turn sends the parallel data to the output pins after processing. For successful operation, the paired decoder and encoder must have the same number of address and data format selected. The serial data and address from matching encoder, received by the decoder, is transmitted by a carrier employing the RF transmission medium providing output to the output pins. Consequently, the HT12E encoder IC is also a series of CMOS specifically for Remote Control applications. The purpose of its use is interfacing the RF. The suitability of the encoder is restricted to 12 bit information consisting of N data bits and address bits. The encoder converts the parallel input from the switches into serial data output. The main work is to encode the 12 bit parallel data into serial data for transmission by the RF transmitter. The 12 bits created is divided in to four data bits and eight address bits. Transmitter circuit diagram Fig 3.1 The voltage of the power source for the transmitter is 6V From the figure above, it is evident that the address lines A0 is connected to Vcc. The line can be connects to the ground via earthing or to Vcc, but one principle that must be upheld is on the receiver end the same principle must be applied. The main reason for the connection is to make the connection between the transmitter and receiver using A0. In addition, external pull up resistors can be added to ensure the signals are not floating between logic gates. Consequently, a 1M? resistor must be placed between OSC1 and OSC2 pins. The transmitter Enable pin (pin 14) is an active low pin, thus as soon as the power connector is activated; it will be ready for data processing. Consequently, the output serial data output DOUT is sent to the RF transmitter module. The address pins (A0, pin 1) are vital and must be same as address in decoder for the circuit to operate effectively. In the circuit, reviewed the address pins are grounded. Fig 3.2 PCB design of a transmitter Fig 3.3 transmitter circuit after soldering components Testing For clarity and success, the transmitter circuit must be tested. The testing of the circuit is conducted using a spectrum analyzer. The analyzer enables the frequency of the transmission. The transmission frequency is 432MHz which is the desired frequency for the circuit. Receiver circuit diagram As stated the address pins (A0) is connected to Vcc same as in the transmitter circuit. The connection facilitates the receiving of the transmitted data. Whenever the receiver receives any data, pin 17 (VT) is enabled by connecting it to the LED then to the ground. Therefore, when the transmitter is away from the receiver, pin 17 will work through giving an alarm by lighting the LED to identify the person who has it. The RF receiver module receives serial data, which is fed directly to pin 14 (DIN). Two resistors of 47K? and 3.9K? are joined and connected between OSC1 and OSC2 making the total resistance 50.9K?. The resistor value obtained from the two resistors is twenty times less than the resistor value in transmitter. The HT12D output, (pins 10-13) achieve high state when the decoder is supplied and moves to low the moment matching data is received by the decoder. Fig 3.4 the PCB design of a receiver Fig 3.5 the receiver circuit after soldering components The outcome of the whole process was to build a transmitter and receiver system for monitoring movement. Conclusion and future developments The main focus and objectives of the work were designing and developing a set of video transmitter and data communication system circuits enabling mobile rescue robot to act as a search and rescue system. From the above explanation and design process, design and implementation process was achieved successfully. The study outcomes for the project were to develop an understanding of the transmitter circuit and illustrating the structure of building a transmitter. The learning outcome of the project is massive; personally, I have understood the design factors for effective and successful development of the receiver and transmitter systems. Additionally, the use of transistors in the design process has been understood. The use of spectrum analyzer helped in improving my experience in the evaluation and analysis of circuits. The Altium designer software was used in the development of the schematics of the design. The design needs improvement in the power side by allowing the use of battery charger regulator for solar panels. The system should use the solar panels to charge the 12 volt battery. The transmission range can be increased by using different kinds of transistors. Audio line can be developed by to improve the transmission and improve the video information transfer. I conclusion, the project was completed perfectly, but the identified areas of improvement will be able to improve the efficiency and promote the success of the data transmission process. Read More