• As I got clarity about operations and controls I understood what components I will require. List of components are as below.
• Very good tutorial on interfacing circuit is given here which I referred.

• Next thing I have to do is to make connections  and sketch general circuit diagram on paper.

•  
• Micro-controllers basically understands digital data as in form of 0 and 1 directly, if we need to interpret some non digital data, we required to convert analog data into digital, and that can be done by ADC module in MCU.
• Atmega 328 MCU have 8 ADC (6 in PDIP package) input channel.
• Apart from 8 ADC channels available on pins, there are also three internal channels that can be selected with multiplexer decoder. These are: temperature sensor-channel 8, band gap reference-1.1V and GND-0V.
• Detailed study documentation is done on ADC in Atmega 328P datasheet, from page number 305.

• The ADC needs a clock pulse to do its conversion. This clock generated by system clock by dividing it to get smaller frequency.
• At higher frequency the conversion is fast while a lower frequency the conversion is more accurate.
• So the Prescaler is provided to produces acceptable frequency for ADC from any system clock frequency.

• The ADC in ATmega32 has 8 channels that means one can take samples from eight different terminal.
• And can connect up to 8 different sensors and get their values separately.

• The registers related to any particular peripheral module(like ADC, Timer, USART etc.) provides the communication link between the CPU and that peripheral.
• One can configure the ADC according to need using these registers, and also get the conversion result using appropriate registers. The ADC has only four registers.
• ADC Multiplexer Selection Register – ADMUX : For selecting the reference voltage and the input channel.
• ADC Control and Status Register A – ADCSRA : As the name says it has the status of ADC and is also use for controlling it.
• The ADC Data Register – ADCL and ADCH : The final result of conversion.

Measuring temperature:

• Selecting the Temperature sensor channel by writing ADMUX.MUX[3:0] to '1000' enables the temperature sensor. The internal 1.1V voltage reference must
• also be selected for the ADC voltage reference source in the temperature sensor measurement

• Once I got to know about circuit flow and components I start making schematic in Eagle.
• Most of the general components listed above I have found from fab and sparkfun libraries.
• I have started to make connection by referring Satshakit, where I learned programmable pins, connection and placement with Atmega 328P.
• Once I understand programmable pins, I have connected it with respective pins of ISP and FTDI header.
• Secondly, thermistor has to be connected with analog pin of microcontroller. So, accordingly I connected thermistor to 23rd Pin of IC.
• 3 mosfets and its interfacing circuit I have connected with IC pin number 9,11 and 12.
• Accordingly I have connected rest of the components to make circuit.

• I have took board with enough size to accommodate to milling of 7*7 cm. I have made my board ready with double sided tape.
• For milling traces I have used 1/64th inch of  milling bit. For drilling holes 1/32th inch endmill and for cutting 1/16th inch of 2 flute endmill I have used.
• As my lab's model MDX-20 was very old and  bed alignment totally has been disturbed, I have milled almost 4 to 5 different boards to get right result.
• In modela half of area was aligned so it could mill small board such as FabISP, but it create milling problem in bigger bead. After lots of iteration to make it align with water-level guage I got almost right result of milling my board.

• For programming I have to connect my board with FabISP, by connecting all six programmable pins.
• Once connected, I want to program it to sense temperature by thermistor, this will require to read certain values by Rx and Tx pins of board.
• In order to find out right boud value I have write program to print hello. After certain trial and error I have got right value as 9600.
• Once done, I wrote program for 100k NTC thermistor and uploaded in board.
• Once program uploaded successfully, I have connected thermistor in 2 pin header.
• As thermistor runs on 5V, I need not to apply 12V supply.
• After connecting thermistor I have tested temperature value by soldering iron heat, which can be seen in below video that, values are increasing as temperature rises due to closeness of soldering iron.

• All the original Eagle design files, milling files, and programming files are attached here as package including program files.

INDIVIDUAL CONTRIBUTION TO GROUP WORK

• Input devices group work we have tested input sensor such as LDR and it's function generator analog graph on Oscilloscope.
• In this week, assignment was completely new to us so we all sit together and work in group how to measure value of input sensor on oscilloscope.