Introduction:
A Liquid level indicator is designed to
indicate and though which people are aware about the level of liquid in
a tank by proper visualization or by proper indication by colored
LED's. The indication or visualization is observed for different tank
level. In this Project four levels are taken such as:
Level (0) : Initially Empty Tank.
Level (1) : Quarter Filled Liquid. 
Level (3) : Quarter3 Filled Liquid.
Level (4) : Fully filled.
After fully filled Buzzer become ON
Name Qty
AT89C51/S51/S52 1
LCD, LM016L 1
Resistor 10k 4
switch (optional), used in proteus
for testing .
Breadbord or PCB
Connecting Wires
Preset 1
Power Supply 5v 1
Connection's
i. Connect the 8 data lines of LCD to P2 AT89C51/S51/S52 Microcontroller.
ii. Connect the LCD control pins with microcontroller such as (RS-P1.0, RW-P1.1, EN-P1.2).
iii. In simulation i have connected switches to check the water level by closing the switches, while implementing in hardware don't use switch. you can connect simple resistor with a lead
which is drown in liquid. Or one can use BC547 with a resistor and a lead.
iv. connect crystal oscillator of 11.0592/12 Mhz with 33uf capacitor to 18 and 19th pin of 8051 which will provide a oscillation that drive the microcontroller IC.
v. connect 16 and 1 pin of LCD to ground and 15 and 2 pin to Vcc. (5V).
vi. connect a 10k Potentiometer to Pin 3 of LCD. the potentiometer is of three terminal .one of the above single terminal is connected to pin 3 and rest 2 pins are connected to Vcc and ground.
** One may connect Read/Write pin to 8051 pin or connect to ground unless reading busy flag.
Access this link below for Source code and Simulation
