this project we use one dc motor for the lift. Few reed sensor to
monitor the lift
this lift when we start the lift then we use start switch. After
pressing a start switch stepper motor start and when it reaches to
the first floor then firstly we sense the floor by reed sensor. Reed
sensor is magnetic sensor, when magnet connected to the lift is
near by the reed sensor then reed sensor is activate and provide a
signal to the controller.
this PC is used to send the signal through optocouplers and relays
to PIC controller. Optocouplers are used to isolate the circuit.
This is the protection circuit which used to protect the PIC
the PIC controller is used to drive the stepper motor through
current amplification circuit. The step motor rotates and the lift
is shifted to first floor and then second and so on.
the ground floor we use reed sensors which are attached to the pic
position of the lift or floor number is displayed on the LCD. We use
16*2 lcd for showing the output..
a family of Harvard
architecture microcontrollers made
by Microchip Technology,
derived from the PIC1650originally developed by General Instrument's
Microelectronics Division. The name PIC initially referred to "Peripheral
popular with both industrial developers and hobbyists alike due to
their low cost, wide availability, large user base, extensive
collection of application notes, availability of low cost or free
development tools, and serial programming (and re-programming with
flash memory) capability.
announced on February 2008 the shipment of its six billionth PIC
powerful (200 nanosecond instruction execution) yet easy-to-program
(only 35 single word instructions) CMOS FLASH-based 8-bit
microcontroller packs Microchip's powerful PIC® architecture into
28-pin package and is upwards compatible with the PIC16C5X,
PIC12CXXX and PIC16C7X devices. The PIC16F73 features 5 channels of
8-bit Analog-to-Digital (A/D) converter with 2 additional timers, 2
capture/compare/PWM functions and the synchronous serial port can be
configured as either 3-wire Serial Peripheral Interface (SPI™) or
the 2-wire Inter-Integrated Circuit (I²C™) bus and a Universal
Asynchronous Receiver Transmitter (USART). All of these features
make it ideal for more advanced level A/D applications in
automotive, industrial, appliances and consumer applications.
To make the robots mobile we need to have motors
and the control circuitry that could control the motors. There are
different kinds of motors available for different application.
These are the motors that are commonly found in the toys
and the tape recorders. These motors change the direction of
rotation by changing the polarity. Most chips can't pass enough
current or voltage to spin a motor. Also, motors tend to be
electrically noisy (spikes) and can slam power back into the control
lines when the motor direction or speed is changed.
Specialized circuits (motor drivers) have been developed to supply
motors with power and to isolate the other ICs from electrical
problems. These circuits can be designed such that they can be
completely separate boards, reusable from project to project.
A very popular circuit for driving DC motors (ordinary or gearhead)
is called an H-bridge. It's called that because it looks like the
capital letter 'H' on classic schematics. The great ability of an
H-bridge circuit is that the motor can be driven forward or backward
at any speed, optionally using a completely independent power
This circuit known as the H-bridge
(named for its topological similarity to the letter "H") is commonly
used to drive motors. In this circuit two of four transistors are
selectively enabled to control current flow through a motor.
opposite pair of transistors (Transistor One and
Transistor Three) is enabled, allowing current to flow through the
motor. The other pair is disabled, and can be thought of as out of
By determining which pair of transistors is
enabled, current can be made to flow in either of the two directions
through the motor. Because permanent-magnet motors reverse their
direction of turn when the current flow is reversed, this circuit
allows bidirectional control of the motor.
It should be clear that one would never want to
enable Transistors One and Two or Transistors Three and Four
simultaneously. This would cause current to flow from Power + to
Power - through the transistors, and not the motors, at the maximum
current-handling capacity of either the power supply or the
transistors. This usually results in failure of the H-Bridge. To
prevent the possibility of this failure, enable circuitry as
depicted in Figure is typically used.
In this circuit, the internal inverters ensure
that the vertical pairs of transistors are never enabled
simultaneously. The Enable input
determines whether or not the whole circuit is operational. If this
input is false, then none of the transistors are enabled, and the
motor is free to coast to a stop.
By turning on the Enable input and
controlling the two Direction inputs, the motor can be made
to turn in either direction.
Note that if both direction inputs are the same state (either true
or false) and the circuit is enabled, both terminals will be brought
to the same voltage (Power + or Power - , respectively). This
operation will actively brake the motor, due to a property of motors
known as back emf, in which a motor that is turning
generates a voltage counter to its rotation. When both terminals of
the motor are brought to the same electrical potential, the back emf
causes resistance to the motor's rotation.
Stepper motors are special kind of
heavy duty motors having 2 or 4 coils. The motors will be stepping
each time when it get the pulse. As there are many coils in the
motors we need to energize the coils in a specific sequence for the
rotation of the motor. These motors are mostly used in heavy
machines. The figure shown below consists of a 4 coil stepper motor
and the arrow mark will rotate when the coils are energized in the
Unlike DC motors stepper motors can
be turned accurately for the given degrees.
Servo motors unlike the stepper motor
it has to be controlled by the timing signal. This motor has only
one coil. It is mostly used in robots for its lightweight and low
power consumption. The servo motors can also be accurately rotated
by the making the control signal of the servo motor high for a
specific time period. Actually the servo motor will be having 3
wires where 2 are for power supply and another one is for the
LCD (Liquid Crystal Display) screen is an electronic display module
and find a wide range of applications. A 16x2 LCD display is very
basic module and is very commonly used in various devices and
circuits. These modules are preferred over seven
segments and other multi
segment LEDs. The reasons
being: LCDs are economical; easily programmable; have no limitation
of displaying special & even custom
characters (unlike in
seven segments), animations and
A 16x2 LCD means it can display 16 characters per line and there are
2 such lines. In this LCD each character is displayed in 5x7 pixel
matrix. This LCD has two registers, namely, Command and Data.
Supply voltage; 5V (4.7V – 5.3V)
Contrast adjustment; through a variable resistor
Selects command register when low; and data register when high
Low to write to the register; High to read from the register
Sends data to data pins when a high to low pulse is given
8-bit data pins
Backlight VCC (5V)
Backlight Ground (0V)
Crystal 11.592 MHz- 1 nos.
On/off Switch- 1 nos.
Diodes IN 4001- 10 nos.
Optocoupler 817- 2nos.
Cap 10µf,0.1 µf,330µf
Transistors -547or 548
Resistances 330 Ω,8.2kΩ,30pf
IC7805 voltage Regulator
Infrared sensors set
Copper Clad board
CRO 20 Mhz
OrCAD for PCB designing
Proteus 7.6 Simulation