Week 10 (Final Semester)

Title: Track checking and soldering

Objective:

• To troubleshoot the PCB traces
• To assembly the components
• To solders the component
• To master the soldering skill

Content:

It is important for the designer troubleshoots the PCB traces before assembly and solders the components. Two possible things might happen in the PCB traces: one is short circuit and the other one is open circuit. Short circuit means two PCB traces are touching to each other. This causes high current flows in the entire circuit and burn out some of the low rating components. Open circuit means there is no connection. When power is on, the PCB does not response. This might be the problem of open circuit. Short circuit can be troubleshoot by using PCB cutter to separate the two touching traces. Open circuit can be troubleshoot by using jumper wire to make the connection between two traces.

After all tracks are repaired, the component can be replace on PCB and start solder one by on using soldering iron and lead. The figure on the bottom is the component that need to be use when soldering

Soldering Iron

                                                                Lead

Analysis:

There are a few things that needs to be considered while soldering, the important thing is of course the safety precautions. These are the list of safety precaution that must follow when soldering

First a few safety precautions:

• Never touch the element or tip of the soldering iron.
  They are very hot (about 400°C) and will give you a nasty burn.
• Take great care to avoid touching the mains flex with the tip of the iron.
  The iron should have a heatproof flex for extra protection. An ordinary plastic flex will melt immediately if touched by a hot iron and there is a serious risk of burns and electric shock.
• Always return the soldering iron to its stand when not in use.
  Never put it down on your workbench, even for a moment!
• Work in a well-ventilated area.
  The smoke formed as you melt solder is mostly from the flux and quite irritating. Avoid breathing it by keeping you head to the side of, not above, your work.
• Wash your hands after using solder.
  Solder contains lead which is a poisonous metal.

Preparing the soldering iron:

• Place the soldering iron in its stand and plug in.
  The iron will take a few minutes to reach its operating temperature of about 400°C.
• Dampen the sponge in the stand.
  The best way to do this is to lift it out the stand and hold it under a cold tap for a moment, then squeeze to remove excess water. It should be damp, not dripping wet.
• Wait a few minutes for the soldering iron to warm up.
  You can check if it is ready by trying to melt a little solder on the tip.
• Wipe the tip of the iron on the damp sponge.
  This will clean the tip.
• Melt a little solder on the tip of the iron.
  This is called 'tinning' and it will help the heat to flow from the iron's tip to the joint. It only needs to be done when you plug in the iron, and occasionally while soldering if you need to wipe the tip clean on the sponge.

Ready to start soldering:

• Hold the soldering iron like a pen, near the base of the handle.
  Imagine you are going to write your name! Remember to never touch the hot element or tip.
• Touch the soldering iron onto the joint to be made.
  Make sure it touches both the component lead and the track. Hold the tip there for a few seconds and...
• Feed a little solder onto the joint.
  It should flow smoothly onto the lead and track to form a volcano shape as shown in the diagram. Apply the solder to the joint, not the iron.
• Remove the solder, then the iron, while keeping the joint still.
  Allow the joint a few seconds to cool before you move the circuit board.
• Inspect the joint closely.
  It should look shiny and have a 'volcano' shape. If not, you will need to reheat it and feed in a little more solder. This time ensure that both the lead and track are heated fully before applying solder.

Conclusion

Now the circuit is complete and after wiring it, the circuit is ready to use. Now, all need to be done is the hardware part of the project. The hardware will be prepared on the next week.

Week 9 (Final Semester)

Title: Drilling


Objective:

• To make a hole on PCB for the component to fit in
• To master the skill  on drilling the PCB

Content:

Drill size is important to make correct holes for the correct electronic components. Difference components have difference size of leads and hence need difference pad sizes and hole. Following figure shows the difference size of drill bits and following table shows the functions of each bit. 

Difference size of drill bits and their functions. 

Analysis:

There are certain things must be considered while drilling. The most importance thing is make sure the drill bits did not cuts the diagram on the PCB. It may unconnected the circuit of PCB. And make sure the size of the drill bits is proportional for the functions just like on the table.

Conclusion:

If the drill accidentally damage the diagram on the circuit, the circuit must be fix with the soldering iron to connect back what the damage that has been done. After successfully finish the drilling, the next thing to do is to track checking and soldering the component. 

Week 8 (Final Semester)

Title: PCB fabrication

Objective:

• To copy the diagram of the circuit on the PCB
• To master on how to fabric the PCB

Content:

PCB fabrication

1.    PCB Drawing: PCB drawing is designed using Protel DXP 2005. Once the PCB layout has been correctly design, it is now prints out the layout on the A4 size transparent OHP paper. Note that, two types of printers are allowed to print the PCB layout, one is laser printer and the other is carbon type of printer such as Photostat machine. Inkjet and dot matrix type of printer will not work.

2.    Prepare tools required:

þ Fluorescent light

þ UV PCB

þ Marker Pen

þ Blade

þ OHP transparent paper

þ Iron (III) chloride, FeCl₃ acid

þ Clean water

þ Thinner

þ Plastic Container

þ Laser printer

þ PCB cutter and trimmer

þ Soldering gun

þ Soldering lead

3.    PCB Cutting: Cut photo PCB size according to the film size.

4.    PCB Photo Etching: Expose the photo PCB in photo etching kit for 8-10minutes.

5.    PCB Developing: Wash the PCB using PCB developer (white powder) for 2 min.

6.    Acid Etching: Etching is a process that removes materials from such us unwanted copper from the PCB surface to achieve circuit design requirements. The etching process used in this project is called chemical etch or pattern etch.

Once the image printed on PCB copper board, now prepare the iron (III) chloride, FeCl₃ solution and ready to do the etching. Add in hot water (80C) and shake the water until you see unused part is ‘washed’ and left only the tracks. The etching process takes around 30 min.

 

7.    Thinner Washing:

This is a process to remove the black ink on the PCB board. The black ink has to remove in order to solder the components. The green coating on PCB can be removed by alcoholic solution and leaving only the PCB trace. After remove the black ink, the PCB is then send for cleaning using normal water.

Analysis:

This project has two circuit, the circuit can do at the same time at the step acid etching and thinner washing to elude the waste. The acid etching is quite dangerous task, so must take safety precaution while doing it such as wearing a glove to cover the hand and the mask to evade from smelling the acid. If the route of the diagram is accidently  cut off, use the soldering iron to connect it back.

Conclusion:

This part of task is really important because the circuit is the heart of the project to operate. Without the circuit, the project cannot operate. After the fabrication is finish, the next thing to for the next week is drilling

Week 7 (Final Semester)

Title: Burn the program into PIC

Objective:

• To download the PIC program to PIC microcontroller
• To master the step

Content:

Step to download the PIC program to PIC microcontroller

1.    Connect PIC programmer to computer via serial port / USB port.

2.    Insert PIC into the programmer socket

3.   Copy ‘Winpic800’ folder to Desktop.

4.    Look for Winpic800.exe in the folder.

 5. Double click Winpic800.exe to start the program.

6. Select the proper PIC name in the top right combo box

7.   Open the .hex file which you want to download into PIC e.g. if your .c filename is ‘abc.c’,    suppose you need to download ‘abc.hex’ into PIC.

Analysis:

For this project there are two PIC need to be burn. Even they are different PIC, the way to download the program on it still the same. 

Conclusion:

The step of downloading the PIC program to PIC microcontroller must be follow, or it will lead to another problem such as PIC dysfunction or even broken PIC. So, it must be done with care.

Week 6 (Final Semester)

Title: Testing the components

Objective:

• To evaluate whether the component function or dysfunction
• To evade any major problem related to the component 

Content:

For this week certain component were tested whether it got problem or not. Not all the test are recorded but here one of the component is being test

This is the video where the lock mechanism is being test. By using 12 volt battery the lock mechanism work fine, there is no dysfunction from this component.

Analysis:

Not all the component can test directly like PIC, it need to be burn and see the PIC work fine or has the problem working. So all that can do is just hoping the component like PIC works fine after the burning.

Conclusion:

This part of task is important to evade any major problem afterwards. This is the safety precaution that need to be take. Finish with this task, the next week will begin to burning the PIC 

Week 5 (Final Semester)

Title : Buying the component

Objective:

• To buy the components for the project
• To discover the suitable place to buy the components

Content:

This project mainly have two parts, which is the transmitter circuit parts and the receiver circuit parts. After write down all the components that need to be bought for the project, the Bizchip company has been chose as a components dealer because of the price and transportation. These are the components that has been bought from the dealer

For transmitter circuit

For receiver circuit

and the additional of remote control car and the lock mechanism that not including on the list.

Analysis:

There are discount that has been given from the dealer because of buying huge numbers of components. And the PIC and the RF sensor has two month warranty if there is some dysfunctional on these components

Conclusion:

All the component has been bought, the next step is to testing the component to make sure the component function.

Week 4 (Final Semester)

Title: Program designing

Objective:

• To design a program proportional with the flow chart of the project
• To master C compiler software
• To master C language

Content:

PCWH C-Compiler Software

PCWH powerful C-Compiler that developed by CCS Co. USA. The software is designed mainly for 8 bit chip microcontroller embedded system. It supports a wide range of PIC micro-controllers, including PIC10, PIC12, PIC14, PIC16, and PIC18. The software also has broad library functions at which programmer can access.

In general, the PCWH C-Compiler allows user:

• Write the C code using advanced code editor.
• By using "include" function, accessing or processing of code become even faster.
• Control the execution of the program at which the "error" will be reported when bugs are detected.

• Samples of program also provided in the helps file.

            To used the software creating a project, make sure a copy of PCWH available in the computer. User can download a 30 days trial copy from http://ccsinfo.com/ccsfreedemo.php. Follow steps by steps on the instruction during installation process and finally user will see an icon of PCWH appears on the desktop of the computer.

Steps to use PCWH C-Compiler

1.    Open PCW C-Compiler Start->All Programs->PIC-C->PIC C Compiler.

2.    ‘File’ -> ‘New’ to start a new file.

3.    Save the file as .c file, it is advisable to put the main file name within 8 chars length, extended file name must be .c, e.g. myprog1.c.

4.    Type / Edit your program.

5.    Save program before compile.

6.    Compile your program using F9.

7.    If any error occurs, please check your program and compile again. Otherwise you won’t get your .hex file.

    

For the project, by using this software, there are two program need to be design which is for the transmitter and the receiver. These two programs are necessary to make sure the project function smoothly. After countless trial and compiling, finally the programs works and ready to use.

Program for transmitter (PIC 16F876A)

#include <16f876A.h>       //use pic16f876a library

#use delay(clock=20000000) //set pic clock speed as 20mhz

#use rs232(baud=4800,xmit=PIN_C6,rcv=PIN_C7,PARITY=N) //set serial interfacing

#fuses hs,protect,nowdt,nolvp //default setting

#byte PORTA=5 //define PORT A address

#byte PORTB=6 //define PORT B address

#byte PORTC=7 //define PORT C address

void main()

{

   int i=0;

   //set i/o for each pin

   set_tris_a(0b00000000); 

   set_tris_b(0b00000000); 

   set_tris_c(0b10000000); 

   output_high(pin_c2); //on led

   delay_ms(1000);

   output_low(pin_c2);  //off led

   delay_ms(1000);

   do

   {

      output_high(pin_c2); //on led

      //send data out

      for(i=0;i<10;i++)

      {

         putc('(');

         putc('1');

         putc(')');

         delay_ms(10);

      }

      output_low(pin_c2);  //off led

      delay_ms(3000);

   }while(1);

}

Program for receiver (PIC 16F877A)

#include <16f877A.h> //use pic16f877a

#use delay(clock=20000000) //set pic speed 20mhz

#fuses hs,noprotect,nowdt,nolvp  //default setting

#use rs232(baud=4800, xmit=PIN_C6, rcv=PIN_C7, parity=N) //set serial interfacing

#byte PORTA=5 

#byte PORTB=6 

#byte PORTC=7 

#byte PORTD=8 

#byte PORTE=9 

int rx_temp1=0;

int rx_temp3=0;

int rcvdata;

int mystat=0;

//receive data from transmitter

#int_rda

void serial_isr()

{

   rx_temp1=getch();

   if(rx_temp1=='(')

   {

      rcvdata=getc();

      rx_temp3=getch();

      if(rx_temp3==')')

      {

         mystat=1;

      }

   }

   rx_temp1=0;

   rx_temp3=0;

}

void main()

{

   int id1sta=0;

   int id1count=0;

   set_tris_a(0b00000000);    //set i/o pin for port a

   set_tris_b(0b00000000);    //set i/o pin for port b

   set_tris_c(0b10011000);    //set i/o pin for port c

   set_tris_d(0b00000110);    //set i/o pin for port d

   set_tris_e(0b00000000);    //set i/o pin for port e

   //initialize interrupt

   enable_interrupts(int_rda);

   enable_interrupts(GLOBAL);

   output_low(pin_d5);  //stop motor1

   output_low(pin_d4);  //stop motor2

   output_low(pin_c5);  //lock door

   output_high(pin_c0);  //on blue led

   output_high(pin_c1);  //on white led1

   output_high(pin_c2);  //on white led2

   delay_ms(1000);

   output_low(pin_c0);  //off blue led

   output_low(pin_c1);  //off white led1

   output_low(pin_c2);  //off white led2

   delay_ms(1000);

   do

   {

      //if RF receiver received valid data

      if(mystat==1)

      {

         mystat=0;

         if(rcvdata=='1')  //if '1' received

         {

            id1sta=1;

            id1count=0;            

         }

      }

      else

      {

         if(id1count<6)    //if transmitter lost less than 3sec

         {

            id1count=id1count+1; //increase timer

         }

         else  //if 3sec reached

         {

            id1sta=0;            

         }

      }

      if(id1sta==1)  //if transmitter in range

      {

         output_high(pin_c5);  //unlock door

         output_high(pin_c0);  //on blue led

         delay_ms(250);

         output_low(pin_c0);   //off blue led

         delay_ms(250);

         if(input(pin_d1)==0) //if on white led button pressed

         {

            output_high(pin_c1);  //on white led1

            output_high(pin_c2);  //on white led2         

         }

         if(input(pin_d3)==0) //if off white led button pressed

         {

            output_low(pin_c1);  //off white led1

            output_low(pin_c2);  //off white led2               

         }

         if(input(pin_d2)==0) //if on motor button pressed

         {

            output_high(pin_d5);  //run motor1

            output_high(pin_d4);  //run motor2

         }

         if(input(pin_c4)==0) //if off motor button pressed

         {

            output_low(pin_d5);  //stop motor1

            output_low(pin_d4);  //stop motor2

         }

      }

      else  //if transmitter out of range

      {

         output_low(pin_c1);  //off white led1

         output_low(pin_c2);  //off white led2                     

         output_low(pin_c5);  //lock door

         output_low(pin_d5);  //stop motor1

         output_low(pin_d4);  //stop motor2

      }     

      delay_ms(500);

      

   }while(1);

}

Analysis:

The program on receiver circuit are longer than the program on the transmitter circuit because the transmitter job is only send a signal to the receiver when the transmitter is on the range, while the receiver  circuit do all the works such as running the motor, switch, led's.

Conclusion:

There are numbers of the software that can be use to design a program. C compiler has been use is because this software is quite simple and easy to use. And with program and circuit is already design, purchasing the component will be the next step of the project