COMPLETE DESCRIPTION
The Complete Description is divided into two Parts :
1. Component Details.
2. Working Principle.
1. The details of the major components used in the invention are as following:
Microcontroller
A microcontroller is a small computer on a single integrated circuit containing a
processor core, memory, and programmable input/output peripherals. Microcontrollers
are used in automatically controlled products and devices, such as automobile engine
control systems, implantable medical devices, remote controls, office machines,
appliances, power tools, toys and other embedded systems. By reducing the size and cost
compared to a design that uses a separate microprocessor, memory, and input/output
devices, microcontrollers make it economical to digitally control even more devices and
processes. Mixed signal microcontrollers are common, integrating analog components
needed to control non-digital electronic systems.
The rnicrocontrollers may use four-bit words and operate at clock rate frequencies as low
as 4kHz, for low power consumption (single-digit milliwatts or microwatts). The MicroController
used in this Invention operates on 11.0592 Mhz which is provided by the
Oscillator.
Oscillator
Even pulses generated by the oscillator enable harmonic and synchronous operation of all
circuits within the microcontroller; It is usually configured as to use quartz-crystal or
ceramics resonator for frequency stabilization. It can also operate without elements for
frequency stabilization (like RC oscillator). It is important to say that program
instructions are not executed at the rate imposed by the oscillator itself, but several times
slower. It happens because each instruction is executed in several steps.
Microcontroller 8051 (AT89c5~)
Pinout Description
IPO DELHI l0-12-2015.17:03
2
Pins 1-8: Port I Each of these pins can be configured as an input or an output.
Pin 9: ReSet: A logic one on thi~ pin disables the microcontroller and clears the contents
of most registers. In other words, the positive voltage on this pin resets the
microcontroller. By applying logic zero to this pin, the program starts execution from the
beginning.
Pins10-17: Port 3 Similar to port I, each ofthest: pins can serve as general input or
output. Besides, all of them have alternative functions:
Pin 10: RXD (Receive Data) Serial asynchronous communication input or Serial
synchronous communication output.
Pin 11: TXD (Transmit Data) Serial asynchronous communication output or Serial
synchronous communication clock output.
Pin 12: INTO Interrupt 0 input.
Pin 13: INTI Interrupt 1 input.
Pin 14: TO Counter 0 clock input.
Pin 15: TI Counter I clock input.
Pin 16: WR Write to external (additional) RAM.
Pin 17: RD Read from external RAM.
Pin 18, 19: X2, XI Internal oscillator input and output. A quartz crystal which specifies
operating frequency is connected to these pins. The Microcontroller operate at a
frequency of II.0592 MHz. ·
Pin 20: GND Ground.
Pin 21-28: Port· 2 If there is no intention to use external memory then these port pins are
configured as general inputs/outputs. In case external memory is used, the higher address
byte, i.e. addresses A8-AI5 will appear on this port. Even though memory with capacity
of 64Kb is not used, which means that not all eight port bits are used for its addressing,
the rest of them are not available as inputs/outputs.·
Pin 29: If external ROM. is used for storing program then a logic zero (0) appears on it
every time the rnicrocontroller reads a byte from memory.
Pin 30: ALE(Address Latch Enable) Prior to reading from external memory, the
microcontroller puts the lower address byte (AO-A 7) on PO and activates the ALE output.
After receiving signal from the ALE pin, the external register (usually 74HCT373 or . .
IPO DELHI 18-12-2015 17:03
3
74HCT375 add-on chip) memorizes the state of PO and uses it as a memory chip address.
Immediately after that, the ALU (Arithmetic and Logical Unit) pin is returned its
previous logic state and PO is now used as a Data Bus. As seen, port data multiplexing is
performed by means of only one additional integrated circuit. In other words, this port is
used for both data and address transmission.
Pin 31: EA(Erase All) By applying logic zero to this pin, P2 and P3 are used for data and
address transmission with no regard to whether there is internal memory or not. It means
that even there is a program written to the microcontroller, it will not be executed.
Instead, the program written to external ROM will be executed. Dy npplyiug lugil: one to
the EA pin, the microcontt:oller will use both memories, first internal then external (if
exists).
Pin 32-39: Port 0 Similar to P2, if external memory is not used, these pins can be used as
general inputs/outputs. Otherwise, PO is configured as address output (AO-A 7) when the
ALE 'pin is driven high (1) or as data output (Data Bus) when the ALE pin is driven low
(0) .
. Pin 40: VCC (Voltage at the Common Collector) +5V power supply.
Input/Output Ports (1/0 Ports)
All 8051 microcontrollers have 4 VO ports each comprising 8 bits which can be
configured as inputs or outputs. Accordingly, in total of 32 input/output pins enabling the
microcontroller to be connected to peripheral devices are available for use. ·
Pin configuration, i.e. whether it is to be configured as an input (1) or an output (0),
depends on its logic state. In order to configure a microcontroller pin as an output, it is
· necessary to apply a logic· zero (0) to appropriate I/0 port bit. In this case, voltage level
on appropriate pin will be 0.
Similarly, in order to configure a microcontroller pin as an input, it is necessary to apply
·a logic one (1) to appropriate port. In this case, voltage level on appropriate pin will be
5V.
The PO port is characterized by two functions. If external memory is used then the lower
address byte (addresses AO-A7) is applied on it. Otherwise, all bits ofthis port are
configured as inputs/outputs. _
The other function is expressed when it is configured as an output. Unlike other ports
consisting of pins with built-in pull-up resistor connected by its end to 5 V power supply,
pins of this port have this resistor left out. This apparently small difference has its
consequences:
IPO DELHI 10-12-·2· 0· J"'!. 5 17:03
If any pin of this port is configured as an input then it acts as if it "floats". Such an input
has unlimited input resistance and indetermined potential.
Port 1
PI is a true I/0 port, because it doesn't have any alternative functions as is the case with
PO, but can be cofigured as general I/0 only. It has a pull-up resistor built-in and is
completely compatible with TTL {Transistor Transistor Logic) circuits.
Port2
P2 acts similarly to PO when external memory is used. Pins of this port occupy addresses
intended for external memory chip. This time it is about the higher address byte with
addresses A8-Al5. When no memory is added, this port can be used as a general
input/output port showing features similar to Pl.
·.Port 3
All port pins can be used as general I/0, but they also have an alternative function. In
order to use these alternative functions, a logic one (1) must be applied to appropriate bit
of the P3 register. In terns of hardware, this port is similar to PO, with t4e difference that
its pins have a pull-up resistor built-in.
The A T89c52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K
bytes of in-system programmable Flash memory. The device is manufactured 1;1sing
Atmel's high-density nonvolatile memory technology and is compatible with the industry-
standard 80C51 instruction set and pinout. The on-chip Flash allows the program
memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer.
By combining a versatile 8-bit CPU with in-system programmable Flash on
a monolithic chip, the Atmel A T89C52 is a powerful rnicrocontroller which provides a
highly-flexible and cost-effective solution to many embedded control. applications.
The AT89C52 provides the following standard features: 8K bytes ofFlash, 256 bytes
of RAM, 32 I/0 lines, Watc~dog timer, two data pointers, three 16-bit timer/counters, a
six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator,
and clock circuitry. In addition, the A T89C52 is designed with static logic for operation
IPO DELHI 10-12-2015 17:03
4
down to zero frequency aml supports two software selectable power saving modes.
The Idle Mode stops the CPU while allowing the. RAM, timer/counters, serial port, and
interrupt system to continue functioning. The Power-down mode saves lh~ RAM contents.
but freezes the oscillator, disabling all other chip Functions until the next interrupt
or hardware reset.
Transformer
A 12-0-12 Step Down Transformer is used in the Invention. This 12 Volt AC is rectified
to 12Volt DC with the help of a Full Wave Rectifier. The 12Volt DC is further. stepped
down to +5V DC by a 7805 IC Chip.
Relay
5
A re~ay is an electrically operated switch. Many relays use an electromagnet to
mechanically operate a switch, but other operating principles are also used, such as solidstate
relays. Relays are used where it is necessary to control a circuit by a low-power
signal (with complete electrical isolation between control and <;;ontrolled circuits).
A type of relay that can handle the high power required to directly control an electric
motor or other loads is called a contactor.
An electro-magnetic Contactor is used in this invention.
2. Working Principle:
Heating and Air-Conditioning Unit of Air-Conditioned Coaches of Railways is Called
Roof Mounted Package Unit (hereinafter referred to as RMPU). There are two modes of
running the RMPU . One is the Automatic mode and the other one is Manual Mode. In
automatic mode there is a thermal cut-off to control the temperature inside AirConditioned
Coaches of Railways. As s~on as the temperature reaches the desired value,
the Thermal cut-off comes ~nto play and theRoofMounted Package Unit is switched off.
Whenever the themal cut-off system becomes faulty and Roof Mounted Package Unit
stops functioning, it is put into Manual mode of operation. In Manual mode, however,
there is no provision of any cut-off, whatsoever of any kind. So the R-oof Mounted
· Package Unit keeps on functioning to its full capacity as long as the Roof Mounted
Package Unit is running in manual mode. Due to this continuous working of Roof
Mounted Package Unit, there is a wastage of energy. Also, since the temperature inside
IPO DELHI
l· 0-12-2015. 17 :·o 3
6
the Railway Coach becomes too low, the reduced temperature leads to discomfort to
passengers. The invention leads to a provision for a Time-Based cut-off. The
Microcontroller is programmable as per need of the topography and climate of the region
in which the train is plying. Asper present status, the invention leads to switching "On"
and "Off' ofthe Roof Mounted Package Unit as stated below:
I. "On" for One hour and then "Off' for the next 5 minutes.
2. "On" for one hour and then "Off' for the next 5 minutes.
3. "On" for 50 Minutes and then "Off' for the next 5 minutes.
4. "On" for 45 Minutes and then "Off' for the next I 0 minutes.
5. ~'On" for 40 Minutes and then "Off' for the next IO minutes.
6. "On" for 30 Minutes and theri "Off' for the next I 0 minutes.
After this cycle, if the cooling in Air-Conditioned Coaches of Railways drops, there is a
Re-set button. Pressing the reset button will start the entire operation from the beginning.
The 220 Volts AC mains supply is fed to a I2-0-12 Transformer which steps down the
voltage to -12 Volts AC. This I2 Volts AC is converted to 12 Volts DC using a full wave ·
rectifier. 5 Volts is required for operation of Micro-Controller. This 5 Volts supply
required for MicroController is given by a 7805 IC which steps down 12 Volts DC
supply to 5 Volts DC supply. The Operating frequency required for operation of Micro
Controller is 11.05982 MHz which is supplied by an Oscillator. The microcontroller
controls the opening and closing of an electromagnetic relay. This electromagnetic relay
controls the opening and closing of the Contactor. The contactor is connected in series
with the 3-Phase supply line of Heating and Air-Conditioning Unit (Called Roof.
Mounted Package Unit) of Air-Conditioned Coaches of Railways. The microcontroller is
programmable as per need.
The connections between various components and at the various ports of Microcontroiler
is shown at the Figure at Annexure-I and Annexure-2.

CLAIMS.
Having described my Invention, I claim
1. A micro-processor controlled Integrated Electronic circuit to control .the time period of
Switch-On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is run in Manual Mode of
Operation, comprising of: ·
(a) A Step-down Transformer.
(b) A Full Wave Rectifier.
(c) A 7805 IC to further step down 12Volts DC supply to 5 Volt DC supply.
(d) A programmable Microcontroller to control the time period of opening and closing of
Relay.
(e) An Oscillator to provide frequency of 11.0592 MHz for operation of the
Microcontroller.
(f) An Electromagnetic relay to operate a Contactor.
(g) A contactor to open and close 3-Phase circuit of Heating and Air-Conditioning Unit (
Called Roof Mounted Package Unit) of Air-Conditioned Coaches ofRailways.
~< ,o'l~
IPO. DELHI 10-12-2015 17:03
2
CLAIMS
2. A micro-processor controlled Integrated Electronic circuit to control the time period of
Switch-On position ofHeating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is run in Manual Mode of
Operation as recited in Claim 1, wherein input voltage is 2?.0 Volts AC(Aitemating
Current) Mains supply. ·
I P 0 DELHI .'\1\ 8· - 1 -) - 2· 0· 1 5 1 7 :· 0 3
3 .
CLAIMS
3. A micro-processor controlled Integrated Electronic circuit to control the time period of
Switch-On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is run in Manual Mode of
Operation as recited in Claim 1, wherein the input 220 Volts AC mains supply is stepped
down to 12. Volts AC using a 12-0-12 Step down Transformer.
IP 0 DEL H I . 10· - 1·2 - ~t. o· 1s 1.7:03
4
CLAIMS
4. A micro-processor controlled Integrated Electronic circuit to control the time period of
Switch~On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is run in Manual Mode of
Operation as recited in Claim 1, wherein the 12 Volts AC supply is converted to 12 Volts
DC supply using a Full Wave Rectifier.
IPO DELHI 10-12~2015· 17:03
5
·cLAIMS
5: A micro-processor controlled Integrated Electronic circuit to control the time period of
Switch-On position ofHeating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is run in Manual Mode of
Operation as recited in Claim 1, wherein the 12 Volts or. supply is further stepped down
to 5 Yolts De supply using a 7805 IC.
r
IPO DELHI 10-12~2015 17 :03;:
. I
I
6
CLAIMS
6. A micro-processor controlled Integrated Electronic circuit to control the time period of
Switch-On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package _Unit) is run in Manual Mode of
Operation as recited in Claim 1, wherein the programmable Microcontroller ( AT89C52)
operates on 5 Volts DC supply.·
IPO DELHI 10-12-2015 17:03
7
CLAIMS
7. A micro-processor controlled Integrated Electronic circuit to control the time period of
Switch-On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches ofRailways when the Heating and Air~
Conditioning Unit (Called Roof Mounted Package Unit) is run in Manual Mode of ·
Operation as recited in Claim 1, wherein a-Programmable Microcontroller ( AT89C::'i?,) is
115~d to operate an cl0ctwmagnedc relay. ·
HI 1 0 - 1·2 - 2 0 1 5 1 7 : 0 3 ... IPO OE.L ·
8
CLAIMS.
8. A micro:..processor controlled Integrated Electronic circuit to control the time period of
Switch-On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is nm in Manual Mode of
Operation as recited in Claim 1, wherein the Microcontroller is programmable and can
open or clo~er~lay circuit for definite intervals of time as per. the program.
~)
IPO DELHI 18-12-2015 17:03
9
CLAIMS
9. A micro-processor controlled Integrated Electronic circuit to control the time period of
Switch-On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches ofRailways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is ·run in Manual Mode of
Operati9n as recited in Claim 1, wherein an Oscillator supplies the operating frequency of
. 1 L0592 Mllz re4uired for the operation of the AT89C52 Microcontroller. ·
I I p 0 DELHI 1 0 ._ 1 2 - 2 0 ~ 5. 1 7 : 0 3
~ . .A .yj'l')
\U I'
10
CLAIMS
10. A micro-processor controlled Integratt:d Electronic Circuit to control the time period
of Switch-On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is iun in Manual Mode of
Operation as recited in Claim 1, wherein an electromagnetic relay is used to "Switch ON"
and/or "Switch OFF" a contactor, for the time period as per the· instructions given to the
electromagnetic relay by the A T89C52 Microcontroller.
IPO DELHI 10-12-2015 17:03
11
CLAIMS
11. A micro-processor controlled Integrated Electronic circuit to control the time period
of Switch-On position of Heating and Air-Conditioning Unit (Called Roof Mounted
Package Unit) of Air-Conditioned Coaches of Railways when the Heating and AirConditioning
Unit (Called Roof Mounted Package Unit) is run in Manual Mode of
Operation as recited in Claim 1, wherein a contactor, as per the <;>pening and closing of
the electromagnetic relay; opens and/or closes the 3-Phase Supply line for Switching
·"ON" the Heating and Air-Conditioning Unit (Called Roof Mounted Package Unit) of
Air-Conditioned Coaches of Railways.