30-07-2012, 10:10 AM
DIGITAL FUEL METRE.
DIGITAL fuel metre.doc (Size: 1.17 MB / Downloads: 65)
INTRODUCTION
IN this project we show that how we convert the analogue fuel meter into digital fuel meter. IN every car there is one fuel tank and with the help of floating boll we check the position of fuel level and then small needle on the car panel show the total quantity of fuel by marking indication.
So to add some innovation in the automobile industry we convert the normal fuel meter into digital fuel meter. We use the same fuel tank and same floating bulb, but instead of needle we use digital display. In the digital display we use one LCD display with micro controller inside. Digital display always display the total amount of fuel and at the same time display the total milage coverage. in the second line shows the reserve fuel with warning alarm indication. If the fuel level goes below reserve fuel then warning alarm is on. If the fuel level is above the set value then lcd display a normal display. We change the setting of the set value with the help of the increment and decrement switch. Assume that if we set the value for 2 li then when fuel level is below the 2 li then only warning alarm is on.
In this project we attach one variable resistor/ potentiometer with the arm of floating boll. Boll always remain on top of the oil level. As the oil level increase boll going upwards, as the oil level down boll on backward. So movement of the boll vary the shaft of the potentiometer. As the potentiometer move resistor of the potentiometer meter is also vary. Output of this potentiometer is amplify by the amplifier circuit. Here in this project we use op-amp as a amplifier. Now output of the amplifier is connected to the input of the ADC. Here we use 0809 ADC. This ADC convert the analogue signal from the potentiometer into digital signal. ADC 0809 is a 8 bit adc, so it is suitable to our micro controller. To control this adc we control few controls of the adc by the controller in software . This adc is 0809 is a 8 bit adc 8 channel adc. We use only one channel of this adc. Output of the adc is connected to the micro controller. Here we use ic 89s51 controller having a 4 ports for input and output. We use one port as a input signal from adc . second port provide a control signal to the controller. One port of the controller is connected to the lcd display .
ANALOG GROUND AND DIGITAL GROUND.
These are the input pins providing the ground for both the analog signal and the digital signal. Analog ground is connected to the ground of the analog Vin while digital ground is connected to the ground of the Vcc pin. The reason that we have two ground pins is to isolate the analog Vin signal from transient voltages caused by digital switching of the output D0-d7, such isolation contributes to the accuracy of the digital data output. In our discussion, both are connected to the same ground; however, in the real world of data acquisition the analog and digital grounds and handled separately.
BASIC NOTES ON LCD
LCD DETAIL .
Frequently, an 8051 program must interact with the outside world using input and output devices that communicate directly with a human being. One of the most common devices attached to an 8051 is an LCD display. Some of the most common LCDs connected to the 8051 are 16x2 and 20x2 displays. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively.
Fortunately, a very popular standard exists which allows us to communicate with the vast majority of LCDs regardless of their manufacturer. The standard is referred to as HD44780U, which refers to the controller chip which receives data from an external source (in this case, the 8051) and communicates directly with the LCD.
HANDLING THE EN CONTROL LINE
As we mentioned above, the EN line is used to tell the LCD that you are ready for it to execute an instruction that you've prepared on the data bus and on the other control lines. Note that the EN line must be raised/lowered before/after each instruction sent to the LCD regardless of whether that instruction is read or write, text or instruction. In short, you must always manipulate EN when communicating with the LCD. EN is the LCD's way of knowing that you are talking to it. If you don't raise/lower EN, the LCD doesn't know you're talking to it on the other lines.