Methodology:

Hardware details

• Microcontroller

The main criteria in selecting a microcontroller are given below in the order of importance :

A. System Requirements: To develop code for 4-bit architectures is harder and handling 4-bit instructions and data widths can limit arithmetic capabilities. Most of the embedded applications are implemented using 8-bit microcontroller as the technology has been around a long time and huge number of controllers is available in the market. They are used from low cost, low speed 4-bit micro replacement to device which deliver tens of MIPS, such as Atmel’s AVR series which achieves a 50 ns instruction cycle time when clocked from a 20 MHz crystal.

B. Memory Architecture: Three different types of memory play an important role in the selection process are (a) program memory i.e. Flash, OTP, ROM and ROM less components, (b) Data memory i.e. on-chip SRAM or external SDRAM and (c) Nonvolatile Memory i.e. EEPROM or Flash. Whether the memory is on-chip or off-chip and how much the size is required may be a key factor defines cost of building the system and speed of operation. For an example Atmel AVR family include Flash memory of 1KB to 128KB, on chip SRAM for data storage and for the storage of configuration information and serial numbers a few bytes of EEPROM are reserved. These golden features make the AVR family more popular in different applications. Flash gives the flexibility to make code changes and provides facility to use In-System-Programmed. Atmel 89C51 and Mega AVR families have the segmented Flash blocks which allows reprogram one segment under control of another segment, without removing the power.

C. Availability: Before going to implement the system, the availability of the device should be checked. The criteria in choosing microcontroller is its ready availability in needed quantities both now and future. If sufficient quantities are available with bright future then no need to be worried about the failure of the project.

D. Size: The size of the IC can be reduced by reducing the number of I/O pins of the microcontroller. Thus physical space required to implement the system is also reduced. So, physical size of IC may well be critical factor for specific applications.

E. Compatibility: The function of a system can be changed or upgraded by changing the software or replacing one IC with another one without incurring heavy additional cost. The new one will be pin compatible as well as function compatible. Atmel’s megaAVR offers our widest selection of devices in terms of memories, pin counts and peripherals, enabling reuse of code and knowledge across projects.

F. Functionality Testing: To check the function of the implemented system correctly the function of the MCU should be checked within the test circuit designed earlier before going to develop the overall system.

G. Power Management: More power means more heat dissipation which leads to wastage of energy. Power consumed by the system determines the lifetime of the battery. Due to reduction in size of the devices the size of the components are reduced and their placement within the design is very compact. This phenomenon makes the devices to be sensitive to the heat dissipated from the MCU and the other peripherals connected with it. In case of Atmel AVR devices Flash based microcontroller can be operated at the voltages down to 1.8V.

H. Manufacturer’s Track Record: Manufacturers should ensure the stability, good performance, better throughput, Reliability; better Serviceability, software support, correctness, wide and timely availability of their products. The products of Atmel are reliable and have a good performance. They have very good software support of AVR Studio Development Environment and are stable in nature.

I. Manufacturer’s Support: The manufacturers should have some facilities like a help line, toll free number, fax number, after-sales support, sufficient knowledgeable and helpful expertise support personnel who will give a prompt reply or they will follow through in a regular manner when they promise to do something.

J. Availability of Development Support: Here the key consideration includes Assembler, Debugger, a code efficient C compiler, emulator, technical support. Trend towards programming in high level language like C is increasing day by day. This language allows using of some portability of code and libraries. This provides more practical consideration using different microcontroller family. Choosing the appropriate Hardware and software development tools is also important while selecting MCU. An integrated development environment (IDE) facilitates the development efforts by providing the project management tools. IDE enables to create source files and their organization in to a project, creation of database for many devices. AVR Studio is very interactive, user friendly, has awesome UI and unlike other compilers, it is totally free of cost.

K. Cost: This is the most important factor. If the system is to be implemented within the limit of the budget calculated earlier the cost of each and every component (selected MCU along with supporting ICs) used to build the system should be minimized tactfully to fulfill the requirements. On chip features will trade with inventory and assembly cost of using extra supporting external components. They can also cut development time and effort by providing a ready integrated solution .

•  Features of Atmega 16:

Ø High-performance, Low-power AVR® 8-bit Microcontroller

Ø Advanced RISC Architecture

– 131 Powerful Instructions – Most Single-clock Cycle Execution

– 32 x 8 General Purpose Working Registers

– Fully Static Operation

– Up to 16 MIPS Throughput at 16 MHz

– On-chip 2-cycle Multiplier

Ø Nonvolatile Program and Data Memories

– 16K Bytes of In-System Self-Programmable Flash

Endurance: 10,000 Write/Erase Cycles

– Optional Boot Code Section with Independent Lock BitsIn-System Programming by On-chip Boot Program

True Read-While-Write Operation

– 512 Bytes EEPROM

Endurance: 100,000 Write/Erase Cycles

– 1K Byte Internal SRAM

– Programming Lock for Software Security

Ø Peripheral Features

– Two 8-bit Timer/Counters with Separate Prescalers and Compare Modes

– One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture Mode

– Four PWM Channels

– 8-channel, 10-bit ADC

8 Single-ended Channels

– Programmable Serial USART

Ø I/O and Packages

– 32 Programmable I/O Lines

– 40-pin PDIP, 44-lead TQFP, and 44-pad QFN/MLF

Ø Operating Voltages

– 2.7 - 5.5V for ATmega16L

Ø Power Consumption @ 1 MHz, 3V, and 25°C for ATmega16L

– Active: 1.1 mA

– Idle Mode: 0.35 mA

– Power-down Mode: < 1 μA

 Specifications of Touché Sensor:

1. Input Signal: Max. 5 Vpp, Variable Frequency Sinusoidal Signal with Frequency Range from 0Hz-6MHz.

2. Number of Electrodes: 1

One is signal source and other is signal sink. Both of them should be placed at different location for reliable operation.

3. Output Signal: Max. 5 Vp, Analog in nature and thus, requires Analog to Digital Converter of 10-bit, 5V, and the reference voltage should be 5V.

•  Software Details:

 ATMEL’s AVR Studio:

Atmel® Studio 6 is the integrated development platform (IDP) for developing and debugging Atmel ARM® Cortex™-M processor-based and Atmel AVR® microcontroller applications. The Atmel Studio 6 IDP gives a seamless and easy-to-use environment to write, build and debug your applications written in C/C++ or assembly code. Atmel Studio 6 supports all 8- and 32-bit AVR; the new SoC wireless family; SAM3, SAM4 and SAM D20 microcontrollers; and connects seamlessly to Atmel debuggers and development kits. Additionally, the IDP now includes two new features designed to further enhance your productivity: Atmel Gallery is an online apps store built in to Studio 6, allowing you to purchase both in-house and third-party development tools and embedded software. Atmel Spaces is a collaborative workspace where you can securely share embedded design and track progress of projects with your peers .

 Key Features:

1. Support for 300+ Atmel AVR and SAM3, SAM4 and SAM D20 devices

2. Atmel Software Framework

a. Vast source code library including drivers, communication stacks, graphic services and touch functionality. ASF enables customers to focus on application differentiation, and accelerates design time.

b. More than 1,600 project examples with source code.

c. ASF Explorer for selecting and integrating ASF components into your own design.

3. Atmel Gallery

a. Online apps store for development tools and embedded software from Atmel and third parties.

b. Easy and secure purchasing process from the Atmel Studio 6 platform.

4. Integrated editor with visual assist

a. Write code faster with visual assist code completion tools.

5. New project wizard

a. Easily create a new project from scratch or from a large library of example designs.

6. In-system programming and debugging

a. Provides a seamless interface to all of Atmel's in-circuit programmers and debuggers.

7. Full debug views

a. Creates a transparent view into CPU and peripherals, enabling easy code development and debugging.

8. Full chip simulation

a. Delivers an accurate model of CPU, interrupts and peripherals.

b. Support for external stimuli.

9. Atmel Spaces

a. Cloud-based collaborative workspace for securely sharing embedded design and track progress of projects with your peers .