Hello everybody welcome back . Today I'm gonna tell how you can display temperature with bar graph on Graphic LCD using PIC microcontroller . The project is very simple to understand if you have concept of Graphic LCD .The program in this project is written in C and Assembly level language & the compiler used to write the C code is mikroC PRO for PIC V. 7.1.0 .You can download complete project (C and Asm file with proteus8 file ) from this link temperature on GLCd .
Graphical Liquid Crystal (GLCD)
Graphical lcds are different from the ordinary alphanumeric lcds, like 16x1 16x2 16x4 20x1 20x2 etc. They (ordinary) can print only characters or custom made characters. They have a fixed size for displaying a character normally 5x7 or 5x8 matrix. Where as in graphical lcd we have 128x64=8192 dots each dot can be lit up as our wish or we can make pixels with 8 dots ie. 8192/8=1024 pixels. We can design a character in a size which we need. More over we can make a picture on a graphical LCD as well. you can learn more about this LCD on this link Graphic LCD
LM35 Temperature Sensor
The LM35 temperature sensor is a semiconductor sensor. It is available in integrated circuit (IC) form. It has 3 pins and the IC is as shown below.
Working Principle of temperature sensor :
Since LM35 IC is semiconductor IC it is based on the principle that the voltage across a diode varies proportionally with the temperature i.e. if the temperature of the environment varies the current across the diode also varies due to which the voltage across base-emitter junction VBE also varies. The relation between the current and the temperature of the diode is stated below:
Where, VT is actual temperature dependent term which is given by:
VT = kT/q
Features of LM35:
- Calibrated directly in Celsius scale ( Centigrade)
- Linear +10 mV/0C scale factor
- 50C Ensured Accuracy (at 250C)
- Works for -550C to 1500C
- Operates in the range of 4V to 30V
- Less than 60µA design drain current
- Low impedance output, 0.1Ω for 1-mA load
- Low self heating, 0.80C in still air
C - code
The code is very easy to understand . First we have defined Control and DATA pins of graphical LCD to PIC microcontroller . Then after we have displayed some text using function Glcd_Write_Text("", ,,); .Since we cannot write box using Glcd_Write_Text(); function we have to make our own box using the function Glcd_Box(x,y,-x,-y,on/off). These box are made to respective temperature and the box is used to represent the temperature . Thats all concept behind this project .
If you have any question about this project please comment below , if you like this project please share this .