The History About The Pic Microcontroller Information Technology Essay

Published: 2021-08-02 08:40:07
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PIC belongs to a family of modified Harvard architecture. Microcontrollers are made by Microchip Technology. It was derived from PIC1650 and developed by General Instrument's Microelectronics Division. The name PIC stands for "Peripheral Interface Controller". PICs are popular with both hobbyist and industrial developers. It is because of low cost, large user base, wide availability, extensive use of application, availability of development tools, and serial programming (and re-programming with flash memory) capability. They are commonly used in educational purpose due to their availability as 'pic logicator' software.
The PIC architecture has the following characteristics:
It has data spaces and separate code (Harvard architecture)
Fixed length instructions will be only in small number
Most of the instructions are single cycle execution (2 clock cycles, or 4 clock cycles in 8-bit models)
By using banking small amount of data space which is addressable can be extended. The data space is typically 256 bytes
Data space is mapped to port, peripheral registers and CPU
The use of accumulator (W0) as a source code is implied. So that it need not be encoded in opcode
Every RAM locations function as registers. It performs as source and/or destination of math and also other functions
A hardware stack is used for storing return addresses
The program counter is mapped into the data space and writable which is used to perform indirect jumps
There is no distinction between memory space and register space. This is due to the fact that RAM serves as both memory and registers. The RAM is generally just referred as register file or simply as registers.
PIC instructions fall into five classes:
Operation on working register (WREG) with 8-bit immediate ("literal") operand. E.g. movlw (move literal to WREG), andlw (AND literal with WREG). One instruction peculiar to the PIC is retlw, load immediate into WREG and return, which is used with computed branches to produce lookup tables.
Operation with WREG and indexed register. The result can be written to either the Working register (e.g. addwf reg,w). or the selected register (e.g. addwf reg,f).
Bit operations. These take a register number and a bit number, and perform one of 4 actions: set or clear a bit, and test and skip on set/clear. The latter are used to perform conditional branches. The usual ALU status flags are available in a numbered register so operations such as "branch on carry clear" are possible.
Control transfers. Other than the skip instructions previously mentioned, there are only two: goto and call.
A few miscellaneous zero-operand instructions, such as return from subroutine, and sleep to enter low-power mode.
The PIC architectures have these advantages:
Easy to learn the instruction set
RISC architecture
Contain built in oscillator
In circuit programming, in circuit debugging and PIC Kit units are available for less than $50
Inexpensive microcontrollers
It can be interface with interfaces like  I²C, SPI, USB, USART, PWM, LIN, CAN, PSP, and Ethernet
The PIC architectures have these limitations:
One accumulator
For accessing whole RAM register bank switching is needed
Operations and registers are not orthogonal
Some instructions can address RAM and/or immediate constants, while others can only use the accumulator
The PIC microcontroller used in this system is PIC16F877A. The pin diagram of PIC16F877A is shown in figure 4 below.
Peripheral Features
• Timer0: 8-bit timer/counter with 8-bit prescaler
• Timer1: 16-bit timer/counter with prescaler, can be incremented during Sleep via external
Crystal /clock
• Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler
• Two Capture, Compare, PWM modules
Capture is 16-bit, maximum resolution is 12.5 ns
Compare is 16-bit, maximum resolution is 200 ns
PWM maximum resolution is 10-bit
• Synchronous Serial Port (SSP) with SPI™ (Master mode) and I2C™ (Master/Slave)
• Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI) with 9-bit address detection
• Parallel Slave Port (PSP) – 8 bits wide with external RD, WR and CS controls (40/44-pin only)
• Brown-out detection circuitry for Brown-out Reset (BOR)
Analog Features:
• 10-bit, up to 8-channel Analog-to-Digital Converter (A/D)
• Brown-out Reset (BOR)
• Analog Comparator module with:
Two analog comparators
Programmable on-chip voltage reference (VREF) module
Programmable input multiplexing from device inputs and internal voltage reference
Comparator outputs are externally accessible
Special Microcontroller Features:
• 100,000 erase/write cycle Enhanced Flash program memory typical
• 1,000,000 erase/write cycle Data EEPROM memory typical
• Data EEPROM Retention > 40 years
• Self-reprogrammable under software control
• In-Circuit Serial Programming™ (ICSP™) via two pins
• Single-supply 5V In-Circuit Serial Programming
• Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation
• Programmable code protection
• Power saving Sleep mode
• Selectable oscillator options
• In-Circuit Debug (ICD) via two pins
CMOS Technology:
• Low-power, high-speed Flash/EEPROM technology
• Fully static design
• Wide operating voltage range (2.0V to 5.5V)
• Commercial and Industrial temperature ranges
• Low-power consumption
3.2.2 RFID READER
For communication purpose RFID readers use RF waves so that it should have one or more antenna. The antenna can be externally attached or can be housing in same module or it may be enclosed as RFID reader electronics. RFID technology use common frequency. Every RFID system that consists of RFID tag and antennas has particular physical characteristics which depend on certain frequency used in order to perform certain operation. To perform programming and integration, RFID readers have propriety method. RFID readers available in different form factors and can be determined by the following (i) the location i.e., environment in which the reader is designed to work, (ii) possibility of external interface like network, power, general purpose input/output (GPIO) and (iii) number of antennas can be supported.
Based on form factor RFID readers have the following categories (i) Stationary RFID Readers or Fixed Position RFID Readers like Industrial RFID Readers, Desktop RFID Readers (ii) Mobile RFID Readers like Handheld RFID Readers, Vehicle Mounted RFID Readers. RFIDs are used in various forms like RFID Printers, RFID Label Applicators, RFID Modules (RFID readers designed to be embedded in something) and RFID Reader Integrated Circuits (ICs).
3.2.3 ZIGBEE MODULE
ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802 standard for personal area networks. ZigBee devices are often used in mesh network form to transmit data over longer distances, passing data through intermediate devices to reach more distant ones. This allows ZigBee networks to be formed ad-hoc, with no centralized control or high-power transmitter/receiver able to reach all of the devices. Any ZigBee device can be tasked with running the network.
ZigBee is targeted at applications that require a low data rate, long battery life, and secure networking. ZigBee has a defined rate 250 kbit/s, best suited for periodic or intermittent data or a single signal transmission from a sensor or input device. Applications include wireless light switches, electrical meters with in-home-displays, traffic management systems, and other consumer and industrial equipment that requires short-range wireless transfer of data at relatively low rates. The technology defined by the ZigBee specification is intended to be simpler and less expensive than other WPANs, such as Bluetooth. ZigBee is a low-cost, low-power, wireless mesh network standard. The low cost allows the technology to be widely deployed in wireless control and monitoring applications. Low power-usage allows longer life with smaller batteries. Mesh networking provides high reliability and more extensive range. ZigBee chip vendors typically sell integrated radios and microcontrollers with between 60 KB and 256 KB flash memory. ZigBee operates in the industrial, scientific and medical (ISM) radio bands; 868 MHz in Europe, 915 MHz in the USA and Australia and 2.4 GHz in most jurisdictions worldwide. Data transmission rates vary from 20 to 250 kilobits/second. The ZigBee network layer natively supports both star and tree typical networks, and generic mesh networks. Every network must have one coordinator device, tasked with its creation, the control of its parameters and basic maintenance. Within star networks, the coordinator must be the central node. Both trees and meshes allows the use of ZigBee routers to extend communication at the network level.
ZigBee builds upon the physical layer and medium access control defined in IEEE standard 802.15.4 (2003 version) for low-rate WPANs. The specification goes on to complete the standard by adding four main components: network layer, application layer, ZigBee device objects (ZDOs) and manufacturer-defined application objects which allow for customization and favor total integration. Besides adding two high-level network layers to the underlying structure, the most significant improvement is the introduction of ZDOs. These are responsible for a number of tasks, which include keeping of device roles, management of requests to join a network, device discovery and security. ZigBee is not intended to support power line networking but to interface with it at least for smart metering and smart appliance purposes.
Because ZigBee nodes can go from sleep to active mode in 30 ms or less, the latency can be low and devices can be responsive, particularly compared to Bluetooth wake-up delays, which are typically around three seconds. Because ZigBee nodes can sleep most of the time, average power consumption can be low, resulting in long battery life. The ZigBee Alliance is a group of companies that maintain and publish the ZigBee standard. The term ZigBee is a registered trademark of this group, not a single technical standard. The Alliance publishes application profiles that allow multiple OEM vendors to create interoperable products. The relationship between IEEE 802.15.4 and ZigBee is similar to that between IEEE 802.11 and the Wi-Fi Alliance. The way that a message propagates through a ZigBee network depends on the network topology. However, in all topologies, the message usually needs to pass through one or more intermediate nodes before reaching its final destination.
The message therefore contains two destination addresses:
Address of the final destination
Address of the node which is the next "hop"
Zigbee devices are of three types: (i) ZigBee Coordinator (ZC): The most capable device, the Coordinator forms the root of the network tree and might bridge to other networks. There is exactly one ZigBee Coordinator in each network since it is the device that started the network originally (the ZigBee Light Link specification also allows operation without a ZigBee Coordinator, making it more usable for over-the-shelf home products). It stores information about the network, including acting as the Trust Center & repository for security keys, (ii) ZigBee Router (ZR): As well as running an application function, a Router can act as an intermediate router, passing on data from other devices and (iii) ZigBee End Device (ZED): Contains just enough functionality to talk to the parent node (either the Coordinator or a Router); it cannot relay data from other devices. This relationship allows the node to be asleep a significant amount of the time thereby giving long battery life. A ZED requires the least amount of memory, and therefore can be less expensive to manufacture than a ZR or ZC.
The ZigBee module used in this system is CC2500. The CC2500 is a low cost true single chip 2.4 GHz transceiver designed for very low power wireless applications. The circuit is intended for the ISM (Industrial, Scientific and Medical) and SRD (Short Range Device) frequency band at 2400-2483.5 MHz. The RF transceiver is integrated with a highly configurable baseband modem. The modem supports various modulation formats and has a configurable data rate up to 500 kbps. The communication range can be increased by enabling a Forward Error Correction option, which is integrated in the modem. CC2500 provides extensive hardware support for packet handling, data buffering, burst transmissions, clear channel assessment, link quality indication and wake-on-radio. The main operating parameters and the 64- byte transmit/receive FIFOs of CC2500 can be controlled via an SPI interface. In a typical system, the CC2500 will be used together with Wireless audio, Wireless keyboard and mouse. The CC2500 is a low cost true single chip 2.4 GHz transceiver designed for very low power wireless applications. The circuit is intended for the ISM (Industrial, Scientific and Medical) and SRD (Short Range Device) frequency band at 2400-2483.5MHz. The RF transceiver is integrated with a highly configurable baseband modem. The modem supports various modulation formats and has a configurable data rate up to 500 kbps. The communication range can be increased by enabling a Forward Error Correction option, which is integrated in the modem. CC2500 provides extensive hardware support for packet handling, data buffering, burst transmissions, clear channel assessment, link quality indication and wake-on-radio. The main operating parameters and the 64-byte transmit/receive FIFOs of CC2500 can be controlled via an SPI interface. In a typical system, the CC2500 will be used together with a microcontroller and a few additional passive components.
GSM MODULE
The network is structured into a number of discrete sections: (i) The Base Station Subsystem (the base stations and their controllers), (ii) The Network and Switching Subsystem (the part of the network most similar to a fixed network). This is sometimes also just called the core network.(iii) The GPRS Core Network (the optional part which allows packet based Internet connections). (iv)The Operations support system (OSS) for maintenance of the network.
GSM is a cellular network, which means that cell phones connect to it by searching for cells in the immediate vicinity. There are five different cell sizes in a GSM network—macro, micro, pico, femto and umbrella cells. The coverage area of each cell varies according to the implementation environment. Macro cells can be regarded as cells where the base station antenna is installed on a mast or a building above average roof top level. Micro cells are cells whose antenna height is under average roof top level; they are typically used in urban areas. Picocells are small cells whose coverage diameter is a few dozen metres; they are mainly used indoors. Femtocells are cells designed for use in residential or small business environments and connect to the service provider’s network via a broadband internet connection. Umbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells. Cell horizontal radius varies depending on antenna height, antenna gain and propagation conditions from a couple of hundred meters to several tens of kilometers. The longest distance the GSM specification supports in practical use is 35 kilometers (22 mi). There are also several implementations of the concept of an extended cell,[9] where the cell radius could be double or even more, depending on the antenna system, the type of terrain and the timing advance.
Indoor coverage is also supported by GSM and may be achieved by using an indoor picocell base station, or an indoor repeater with distributed indoor antennas fed through power splitters, to deliver the radio signals from an antenna outdoors to the separate indoor distributed antenna system. These are typically deployed when a lot of call capacity is needed indoors; for example, in shopping centers or airports. However, this is not a prerequisite, since indoor coverage is also provided by in-building penetration of the radio signals from any nearby cell. GSM networks operate in a number of different carrier frequency ranges (separated into GSM frequency ranges for 2G and UMTS frequency bands for 3G), with most 2G GSM networks operating in the 900 MHz or 1800 MHz bands. Where these bands were already allocated, the 850 MHz and 1900 MHz bands were used instead (for example in Canada and the United States). In rare cases the 400 and 450 MHz frequency bands are assigned in some countries because they were previously used for first-generation systems. Most 3G networks in Europe operate in the 2100 MHz frequency band.
Regardless of the frequency selected by an operator, it is divided into timeslots for individual phones to use. This allows eight full-rate or sixteen half-rate speech channels per radio frequency. These eight radio timeslots (or eight burst periods) are grouped into a TDMA frame. Half rate channels use alternate frames in the same timeslot. The channel data rate for all 8 channels is270.833 kbit/s, and the frame duration is 4.615 ms. The transmission power in the handset is limited to a maximum of 2 watts in GSM 850/900 and 1 watt in GSM 1800/1900. GSM has used a variety of voice codecs to squeeze 3.1 kHz audio into between 6.5 and 13 kbit/s. Originally, two codecs, named after the types of data channel they were allocated, were used, called Half Rate (6.5 kbit/s) and Full Rate (13 kbit/s). These used a system based upon linear predictive coding (LPC). In addition to being efficient with bitrates, these codecs also made it easier to identify more important parts of the audio, allowing the air interface layer to prioritize and better protect these parts of the signal.
GSM was further enhanced in 1997 with the Enhanced Full Rate (EFR) codec, a 12.2 kbit/s codec that uses a full rate channel. Finally, with the development of UMTS, EFR was refactored into a variable-rate codec called AMR-Narrowband, which is high quality and robust against interference when used on full rate channels, or less robust but still relatively high quality when used in good radio conditions on half-rate channels. One of the key features of GSM is the Subscriber Identity Module, commonly known as a SIM card. The SIM is a detachable smart card containing the user's subscription information and phone book. This allows the user to retain his or her information after switching handsets. Alternatively, the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM, or only a SIM issued by them; this practice is known as SIM locking.
This GSM Modem can accept any GSM network operator SIM card and act just like a mobile phone with its own unique phone number. Advantage of using this modem will be that you can use its RS232 port to communicate and develop embedded applications. Applications like SMS Control data transfer, remote control and logging can be developed easily. The modem can either be connected to PC serial port directly or to any microcontroller. It can be used to send and receive SMS or make/receive voice calls. It can also be used in GPRS mode to connect to internet and do many applications for data logging and control. In GPRS mode you can also connect to any remote FTP server and upload files for data logging. This GSM modem is a highly flexible plug and play quad band GSM modem for direct and easy integration to RS232 applications. Supports features like Voice, SMS, Data/Fax, GPRS and integrated TCP/IP stack. Some of the applications using GSM are as follows SMS based Remote Control and alerts, security applications, sensor Monitoring, GPRS Mode Remote Data Logging. GSM modem has the following features like highly reliable for 24x7 operations with matched antenna, status of modem indicated by LED, simple to use & low cost, Quad Band Modem supports all GSM operator SIM cards. The GSM modem is based GSM Module number SIM900D from Simcom. The new SIM900 is an ultra compact and reliable wireless module. This is a complete Quad-Band GSM/GPRS module in a SMT type and designed with a very powerful single-chip processor integrating AMR926EJ-S core allowing you to benefit from small dimensions and cost-effective solutions. Featuring an industry-standard interface, the SIM900D delivers GSM/GPRS 50/900/1800/1900MHz performance for voice, SMS, Data, and Fax in a small form f-factor and with low power consumption. With a tiny configuration of 33mm x 33mm x 3mm, SIM900D can fit almost all the space requirements in your M2M applications, especially for slim and compact demands of design.
LCD
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 so on. 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. The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD.16x2 LCD is used in this proposed system. It is used to display temperature and power parameters. Its features are
5 x 8 dots with cursor
Built-in controller (KS 0066 or Equivalent)
+ 5V power supply (Also available for + 3V)
1/16 duty cycle
B/L to be driven by pin 1, pin 2 or pin 15, pin 16 or A.K (LED)
N.V. optional for + 3V power supply
3.2.6 ALARM
Alarm is set to indicate abnormal condition caused due to overload, high temperature or any mismatch between master and slave tags. A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarm devices, timers and confirmation of user input such as a mouse click or keystroke. Early devices were based on an electromechanical system identical to an electric bell without the metal gong. Similarly, a relay may be connected to interrupt its own actuating current, causing the contacts to buzz. Often these units were anchored to a wall or ceiling to use it as a sounding board. The word "buzzer" comes from the rasping noise that electromechanical buzzers made. A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal source, driven with a piezoelectric audio amplifier. Sounds commonly used to indicate that a button has been pressed are a click, a ring or a beep. Its uses are:
Annunciator panels
Electronic metronomes
Game shows
Microwave ovens and other household appliances
Sporting events such as basketball games
Electrical alarms
3.3 SMART NODE
3.3.1 TEMPERATURE MODULE
Its main characteristics are:
The output voltage is proportional to temperature
It directly calibrate in degree Celsius
It has a guaranteed accuracy
Operates between 4 and 30V supply
Low output impedance
Low cost
It does not require additional circuitry to calibrate externally
It can be easily integrated in a control circuit
Due to its low power current that occurs very low heating
It is encapsulated in different types, the most commoTO70-92 is used by low power transistor
The LM35 can be applied easily in the same way as other integrated-circuit temperature sensors. It can be glued or cemented to a surface and its temperature will be within about 0.01°C of the surface temperature. This presumes that the ambient air temperature is almost the same as the surface temperature; if the air temperature were much higher or lower than the surface temperature, the actual temperature of the LM35 die would be at an intermediate temperature between the surface temperature and the air temperature. This is especially true for the TO-92 plastic package, where the copper leads are the principal thermal path to carry heat into the device, so its temperature might be closer to the air temperature than to the surface temperature. To minimize this problem, be sure that the wiring to the LM35, as it leaves the device, is held at the same temperature as the surface of interest. The easiest way to do this is to cover up these wires with a bead of epoxy which will insure that the leads and wires are all at the same temperature as the surface, and that the LM35 die’s temperature will not be affected by the air temperature.
3.3.2 RELAY AND DRIVER CIRCUIT
This relay and driver circuit constitutes to form control module. Relay status depends on control instruction from microcontroller. The switching ON/OFF operation in relay used to control the power at the outlet. A relay is an electro-magnetic switch which is useful if you want to use a low voltage circuit to switch on and off a light bulb (or anything else) connected to the 220v mains supply. The current needed to operate the relay coil is more than can be supplied by most chips (op. amps etc), so a transistor is usually needed. Use BC109C or similar. A resistor of about 4k7 will probably be alright. The diode is needed to short circuit the high voltage "back emf" induced when current flowing through the coil is suddenly switched off. Relays are components which allow a low-power circuit to switch a relatively high current on and off, or to control signals that must be electrically isolated from the controlling circuit itself. Newcomers to electronics sometimes want to use a relay for this type of application, but are unsure about the details of doing so. Here is a quick rundown. To make a relay operate, you have to pass a suitable pull-in and holding current (DC) through its energizing coil.
And generally relay coils are designed to operate from a particular supply voltage. In each case the coil has a resistance which will draw the right pull-in and holding currents when it is connected to that supply voltage. So the basic idea is to choose a relay with a coil designed to operate from the supply voltage you.re using for your control circuit (and with contacts capable of switching the currents you want to control), and then provide a suitable relay driver circuit so that your low-power circuitry can control the current through the relay coil. Typically this will be somewhere between 25mA and 70mA. Often your relay driver can be very simple, using little more than an NPN or PNP transistor to control the coil current. All your low-power circuitry has to do is provide enough base current to turn the transistor on and off. LEDs are used to indicate the condition of the system. Green LED used to indicate normal condition and Red LED used to indicate abnormal condition.
3.3.3 POWER MEASUREMENT MODULE
The power measurement module is used to calculate current and voltage reading. The power measurement module is primarily used for the power measuring IC, with an error margin of 0.1%, and matching the request of IEC61036/IEC60687, IEC62053-21, and IEC62053-22. This IC incorporates two second-order, 16-bit ADCs; all the signal processing required performing active and apparent energy measurements, line-voltage period measurements, and root-mean-square (rms) calculations on the voltage and current channels. It can provide a serial interface (SPI) to read data.
Its features are:
Micro controller based design
3 Phase 4 wire AC Voltage Monitoring
AC current measurement (external CT)
Frequency measurement
Apparent & Real Power measurement (KVA & KW)
Power factor measurement
Energy measurement (KWh)
Simple push button for calibration & menu navigation
Install as Power Sensor, or as Power Meter
RS-485 port for Remote Monitoring

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