Case Study of Embedded Systems

Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56
Case Study of Embedded Systems
Mr. Anand H. D.
1
Department of Electronics & Communication Engineering
Dr. Ambedkar Institute of Technology
Bengaluru-56

Digital Camera Embedded Systems in Automobile Smart Card Reader
How to Automated Meter Reading System
Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 2
SYLLABUS:
Digital camera
Embedded Systems in Automobile
Smart Card Reader
Automated Meter Reading System

Digital Camera
MCU
Clock Unit
Digital
Media
Processor
Flash Memory SD RAM
SD/CF/MMC
expansion slot
Analog
Front end
USB/IEEE 1394
interface
Touch screen
LCD control
TFT LCD
Display
User Interface
Buttons
Shutter &
Focus
control
CCD/CMOS
Image Sensor LENS
Battery Monitor
&
charge control
DS2770
Voltage
Regulator
LM7805
S/W
controlled
Battery
ON/OFF
Power Supply unit
R
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Components of digital
camera

Digital Camera
• Device for capturing and storing images in the form of digital data in place of conventional paper/film
based image storage.
• it contains lens and image sensors for capturing the image, LCD for displaying the captured image.
• uses interface buttons to control the operation of device and communication interface to connect it
with PC to transfer captured images.
• like normal film camera, it uses lens to focus the scene which will be captured as an image.
• in normal camera image is captured in a photo film, later developed to recreate image. In digital
camera image is captured electronically.
• Charge Coupled Device (CCD) or CMOS image sensors are used for capturing the image.
when exposed to light these sensors produce electrons which in turn generates analog voltage
signals. These analog signals are post processed (filtered, amplified and digitized) by an Analog Front
End (AFE) system
AFF ICs are available from various manufacturers like Texas instruments.
• the digitized data is fed to digital media processor, which implements various compression algorithms
like JPEG, TIFF etc. for compressing the raw image data.
Digital Media Processor may contain DMA to transfer compressed image directly to storage
memory.

Digital Camera
• digital camera is powered by rechargeable battery and monitoring and charging control is carried out
by a battery charge control and monitor IC which is under control of ‘System Control ‘unit .
• provision for interfacing storage memory devices like SD/CF/MMC cards are implemented. The
digital camera can be connected to PC through communication interface like USB, IEEE 1394 etc.
supported by device for image transfer.
• Now a days, a single chip SOC incorporating both image processor and 16/32 bit microprocessor in
single chip IC are available..
• Resolution of digital camera is expressed in terms of megapixels.
It represents pixels per inch of image sensing device. As no. of pixels increases, image quality also
increases.
• various system control tasks and image capturing and processing tasks for digital camera are
implemented using an embedded OS.
• the various system functions like shutter control and zooming control is performed by ‘System
Control ‘unit which is implemented using 16/32 bit microprocessor/microcontroller.

Digital Camera Embedded Systems in Automobile
Embedded System Application
Engine Control
System
Speed Control &
Break System
Personal & Car
Safety System
Seat & Pedal
Controls
ACHVWLT
Controller
Fuel
Injection
Control
Anti-lock breaking, automatic breaking, CMB,
Regenerative break system
Voice activation & commands
Route and Traffic monitor
system
Automobile status
monitoring & data logging
infotainment systems &
text to speech converter
Immobilizer unit
ACC Airbag
Vicinity Next
RKE SRC MHSAPM
Embedded Systems in Automobile

• Engine control: automatic control of fuel injection.
• Speed control and brake: are Automatic Cruise Control (ACC), anti-lock braking, automatic
braking and Regenerative braking.
• Safety Systems: for personal safety and car safety. Personal safety is by multiple and variable speed
airbags. Airbags are used for cushioning.
rapid inflation of the bag in case of collision followed by deflation.
Car safety is provided by Remote Key entry (RKE) and immobilizer unit.
 RKE system has embedded CPU and software to control door locks and immobilizer unit
immobilizes the car if unauthorized user attempts to drive the car away.
Security system includes alarms, vicinity alert and lane departure alert. CMB- Collision Mitigation
Brake System.
• Seat and pedal controls: includes Seat Restraint Controller (SRC) and Memory Heated Seat
Adjustable Pedal Module (MHSAPM).
• Car environment controllers: ACHVWLT Controller to control the Air Conditioning, Heater,
Ventilation, Windows, Light and temperature.
• Route and traffic monitors: done by GPS (Global positioning System), mapping, GPS guided
route programming and route planners.

• Automobile Status Monitoring: data loggers, driving assistance device management, steerable
headlights, windshield IR camera, windscreen heads up display, night vision assistance.
• System Interface for commands, voice activation and interfacing: soft programmable
buttons, voice commands, BT interfacing for handfree telephony and wireless Personal connectivity in
automobile, Wi-Fi internet connectivity, GSM/CDMA for mobile connectivity.
• Infotainment Systems: displayed text to speech connector, GPS based car location and surrounding
area maps, cached traffic reports for real time traffic monitoring, cassette players, VCD/DVD players
and handfree telephony using BT and GSM/CDMA
Discrete Components that are integrated to Central Sensing System
1. RTC and Watchdog timers
2. Real time control for electronic, electromechanical and mechanical system.
3. Adaptive Cruise Control: constant speed in cruise mode and decelerated when vehicle comes in
front at a distance less than safe and to accelerate again to cruise mode in adaptive mode.
4. Data Acquisition System:
(a.) for current date and time display, (b.) external temperature, (c.) internal temperature, (d.) total
distance covered, (e.)Road speed of vehicle in km/hr for ACC, speedometer and speed warning, (f.)
engine speed in RPM, (g.) coolant temperature, instances of its excess 115 degree

Celsius and consistency within 80-90 degree Celsius, (h.) illumination levels at display panels and
inside the vehicle, (i.) fuel levels (empty, R1, R2, R3, 1/4, 3/8, 1/2, 5/8, 3/4, 7/4 or full), (j.)oil
pressure, for oil pressure warning system, for engine speed above 3000 rpm (k.) presently engaged
gear information and (l.) front end car distance,
5. Front panel switches and display controls.
6. Port for alarm signal – beep and buzzer sound system, Pictogram.
7. Diagnostics computations: driving malfunctions statistics and analysis results for fast fault
diagnosis by mechanic.
8. Multimedia information.
9. Control Area Network interfaces.
10. Serial Communication Interfaces (SCI), transmitter, receiver.
Embedded systems used in car can be designed using ASICs, Microcontrollers, DSPs like 80x51,
68HC 11/12, PIC, C167, ADSP2106x, 68HCOx, MCORE, Star12, TMS470, Hitachi H852xxx
series and ARM 9 based ST9 series.

Oscillator
Unit
Microcontroller
AT89C51
Program Memory Data Memory
Communicati
on Module
RS-232/USB
Watchdog
Timer
Smart Card
Reader IC
Keypad
LCD & LED Interface
Battery Monitor
&
charge control
D52770
Voltage
Regulator
LM7805
S/W
controlled
Battery
ON/OFF
Power Supply unit
R
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Smart Card Reader System

• smart card is a credit card sized plastic card containing a memory or a ‘CPU and memory’.
memory is in order of a few bytes to a few kilo-bytes.
• smartcard follows a specific command sequence for data read/write operations.
• based on interface between smartcard and reader unit  contact type
 contactless
contact type requires physical contact between the reader and smartcard, follows 150-7816 standard.
contactless type doesn’t require physical contact between the reader and smartcard for data
communication.
communication occurs over air interface and uses radio-frequency waves for data
transmission. 13.56 Mhz  Radio frequency is commonly used
•We are going to design a battery operated contactless smartcard reader (Handheld Reader).
A rechargeable Li-Io battery (say 7V with capacity 1000 mAh) is used as power source for handheld.
The battery parameter monitoring and charging is controlled using a battery monitor and charge
control IC (like D52770 from Maxim Dallas Semiconductor)
The host processor can be an 8/16 bit microcontroller (like 8051/PIC)
The device power ON is controlled through a push bottom switch.

A single chip contactless smartcard read/write IC contains CPU (control logic) read/write memory,
analog circuits (for data modulation and demodulation), transceiver unit for RF data transmission &
reception, antenna driver circuitry.
For handled reader to communicate with desktop machine, a communication channel using either
USB or RS-232C is implemented in the reader.
The I/O unit of system includes a matrix keypad for user inputs and a graphical/alphanumeric LCD
for visual indications.
LEDs are used for various indications like ‘charging’, ‘battery low’, ‘Busy/Error’ etc.
The oscillator and reset circuitry generates necessary clock and reset signals for the proper operation
of the host processor and smart card read/write IC.
Watchdog timer unit provides the necessary clock and reset to the system in case of system
misbehavior.
sometime Watchdog Timer comes as a part or separately interface. Watchdog interrupt is connected
to one of the interrupt lines of processor.

Most of Microcontroller contain built in data memory and program memory. If on-chip memories are
not sufficient for application, external memory chips can be used.
Firmware requirements are:
1. Startup task
2. Battery monitoring & charge controlling tasks
3. Card read/write operation task
4. Communication task
5. Keyboard scanning task
6. LCD update
7. Watchdog timer expire event.

Startup task and Keyboard scanning task can be implemented either as a polling task or as Interrupt
driven task.
The Startup task implements necessary start-up operations like setting microprocessor interrupts,
configure the ports of host processor, initialize the smartcard reader IC etc.
The Battery monitoring & charge controlling tasks reads various registers of battery monitor IC,
checks the presence of charger and initiates a charge command, terminates charging when the
battery is full, produce warning signal when battery voltage is below a threshold value and switch
off the unit if the battery voltage falls below critical threshold voltage value. This task is assigned
the highest priority to avoid data corruption in case of power down.
The Card read/write operation task is responsible for implementing communication sequence for data
read/write operation with the card. The sequence varies with standards (ISO/IEC 1443 A/B,
ISO/IEC 1593 etc. supported by read/write IC

The typical read/write operations is as follow:
1. Initiates ‘Request’ command for checking the presence of cards in the vicinity of reader. If card
present, it responds to reader with ‘Answer to request (ATR)’.
2. After receiving ATR, reader sends a command to capture the serial number of all cards present in
the field. Most of ICs implement special algorithms to capture & decide serial no. of all cards
present in the field.
3. Reader selects the serial number of a card and sends a command to select the specified card. The
card whose serial number matches with the one sent by reader responds to the reader while all other
cards in the field enters sleep state. Communication channel is established between reader and card.
4. Reader authenticates the card with encrypted key. Different mechanisms are used by different
family of cards and readers for implementing authentication.
5. Reader sends read/write command to card along with details of the memory area which the reader
wants to access. Memory of card is segmented into different sectors and each sector may further
divided into blocks. Each block holds a fixed no. of data types.

The Keyboard scanning task scans the keyboard and identifies the key pressed and perform operation
corresponding to the key press. This can be implemented as a task or Interrupt Service Routine if
keyboard hardware supports interrupt generation.
The LCD update task updates the LCD with new data. This task can be invoked by other task like
keyboard task, battery monitoring task, card read/write task and communication task for displaying
various information.
The communication task handles reader communication with host PC. Communication interface can be
either RS-232 or USB, This tasks can also be implemented as ISR.
 Most processor supports serial interrupt for handling serial data transmission using UART & RS-
232. If USB interface is used then interrupt line of USB is connected to interrupt line of processor.
 watchdog Timer expiration ISR handles the actions corresponding to Watchdog Timer event.
 Firmware can be implemented as super-loop model or using an RTOS scheduler like OS-II or RTX-
51 or VxWorks for scheduling task.

Voltage
Sensor
Current
Sensor
ADC
Micro-
controller
LCD
LCD
Interface
Wired AMR Interface
(Power Line Communication)
Power Line Modem
Serial Interface
SerialInterface
Wireless AMR Interface
RF
Transceiver
matching
circuit
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Single Chip
(Energy meter IC)
Automated Meter
Reading (AMR) System

• automates the utility metering (like electricity, water and gas consumption)
• it replaces the existing manual meter reading operation
•AMR transfers meter reading data automatically to a central station or operator for billing and usage
monitoring purpose
•Data is transferred over a wireless communication channel or a wired communication medium
•RF transceivers, GPRS based communication over GSM network are example for wireless AMR data
transfer
Power Line Communication (PLC) is electricity metering for wired AMR data transfer, it uses power
carrying lines for data communication
•AMR system consists of AMR Data Transmission unit which is interfaced with utility meter and a
remote AMR Data Receiver unit which collects the data for billing and usage monitoring
•Data transmission interface can be built as an integral part of utility meter or can be built as an add-on
module for existing utility meters.

• Application Specific Standard Product (ASSP) ICs integrating both utility metering capability and
AMR Interface is available for building a utility meter with integrated AMR interface.
•AMR enabled utility meter can be built using a low cost micro-controller with an AMR interface.
•It contains an energy metering unit and a wireless/wired Automated Meter Reading (AMR) interface.
energy metering unit records the electricity consumption.
•A single chip energy meter IC forms the heart of energy metering unit. It contains a high performance
microcontroller unit, integrated ADCs and LCD controller unit etc.
•The instantaneous power consumption in a electric circuit is given by P=VI where V = instantaneous
Voltage and I = Instantaneous Current.
I is measured using current sensor circuit which essentially consists of a current sensing resistor and
an instrumentation amplifier for signal conditioning. The conditioned current signal is fed to energy
metering IC.
•ADC present in energy metering IC digitizes the instantaneous current value.

• The voltage sensing element senses instantaneous voltage and it is fed to energy metering IC for
digitizing.
•Microcontroller present in energy metering IC computes instantaneous power, the average power and
stores it in EEPROM memory.
It also displays parameter like instantaneous current, voltage, electricity consumed in KWh units on
LCD
•The MSP430 chip from Texas Instruments is typical example of a single chip energy metering IC.
•AMR interface to energy meter can be provided through RF interface or PLC module
RF interface is best suited for short range automated reading application like handheld device based
recording of energy consumption
The meter reading official carries the handheld device.
•The specific energy meter whose reading is to be recorded cn be selected by sending unique meter
identification number (meter id) of the meter and then initiating automated meter reading operation.

• RF interface consists of RF transceiver and impedance matching circuit and an antenna for RF data
transfer
•Impedance matching circuit consists of capacitor, resistors and inductors and it tunes the circuit for
required frequency.
•RF transceiver is responsible for RF data modulation and demodulation
•Antenna is a metallic coil for transmitting and receiving RF data
•The interface between energy metering unit and RF module is implemented through serial interface
like SPI, I2C etc..
•The firmware running in the microcontroller of single chip energy meter IC controls the
communication with RF module.
•PLC based AMR makes use of power line modem for interfacing power lines with energy metering
unit for data communication.
The PLC modem provides bi-directional, half duplex, data communication over the mains.

PLC modem is interfaced with microcontroller in energy metering IC through serial Interface like
UART, SPI etc.
Texas instruments ‘F28x’ controller platform provides a Cost Effective means to implement PLC
technology
•GPRS based communication over GSM is also used
•The firmware requirements for building AMR enabled energy meter can be divided into following
tasks:
1. Startup task
2. Automatic meter data transfer task
3. Energy consumption recording task
4. LCD update task
The startup task deals with initialization of various port pins, interrupts, stack pointers etc. for
microcontroller, initialization of RF interface, LCD

The automatic meter data transfer task records energy consumption. Energy metering SOC contain
dedicated Hardware units for calculating energy consumption based on I and V values and will be
available in some dedicated registers, this task can read this values, update EEPROM periodically c
The energy consumption recording task can be implemented as a periodic task as a command driven
operation in which meter reading is sent up on receiving a command from host system.
for command driven implementation, a set of command interfaces are defined for
communication between AMR enabled meter and host.
each AMR enabled meter holds a unique meter id and firmware can be implemented in such a
way that AMR module responds only when meter ID sent matches with that stored in EEPROM
The LCD update task updates LCD when a change in display meter occurs.
can be implemented as super loop with interrupts or as RTOS like microcontroller/OS-II.

Reference
Shibu K V, “Introduction to Embedded
Systems”, First Edition, Tata McGraw Hill
Education Private Limited, 2009

Prepared by Prof. Anand H D,Dept. of ECE,
Dr. AIT, Bengaluru-56
25

Case Study of Embedded Systems

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