Week 9 – Solder Sensor/Control Board (week 1)

Now its time to focus on the part of the project that was absolutely vital to get working first time. So after the obvious soldering all components in etc, paying very careful attention to which way the components went in place, which were polarised and which were not polarised by looking at the datasheets on moodle that were given to us. Also had to pay attention to the photodiode which was reverse biased as this could cause problems down the line.

The photodiode is very small with tiny legs making it hard to distuingish where the anode and cathode is, to the datasheet folder!!

After some, well a lot of time spent trying to trawl through the datasheet I found out that the cathode end is the one with the little piece sticking out of the side of the leg, and I had to stick the cathode end into the positive terminal on the circuit as its reverse biased. Below is the datasheet where I figured out where the cathode is.

Photodiode

 

And below is my complete sensor and control board!!

Sensor Control Finished PCB

Week 8 – LCD Bench Test (week 2)

Now I know that the LCD board works (except for the half lit LED haha) , I can move on to test whether the actual LCD screen itself works and displays messages the way I want. Using the arduino software along with my Arduino UNO, I began to write my first piece of wiring language, here goes nothing!

I knew exactly what I needed to do because of my switch menu algorithm, this actually came in handy even tho I moaned a lot about it haha! Id start off with my Welcome Message, then onto my  Temperature value, humidity value, and light value all being displayed on screen one after another by the press of the mode select button on the actual board.

Arduino Code

// include the library code:
#include <LiquidCrystal.h>
#include <math.h>
LiquidCrystal lcd(12,11,5,4,3,2);

// *** Variable decalarations ***

const int switchPin = 8;
int sw_state = 0; //new value of the mode switch
int no_of_switch_presses =0; //number of presses of the mode switch
int val;// store val of mode switch
int old_val=0; //store the previous value of valof the mode switch
int FAN=6;//declaring fan pin
int ledon=13;//declarin led pin
float TC;//making TC a global variable so it can be read from the function
float LuxVal;//making the Lux Value a global variable so it can be read from the function

void setup()
{
pinMode(switchPin,INPUT); // Set as input for the mode switch
pinMode(ledon,HIGH);//putting the LED on the LCD board constantly on
lcd.begin(8,2);//setting the cursor for the LCD screen
}

void loop(){
// **** Mode Select ****

val = digitalRead(switchPin); // Read the mode switch
if ((val == LOW) && (old_val ==HIGH)) {
no_of_switch_presses = no_of_switch_presses +1;
//Update the number of switch presses and inplement soft switch debounce
delay(50); // 50ms debounce delay
}
old_val = val; //val is now old so store it

digitalWrite(ledon,HIGH);

// Display whichever dipslay mode has been selected
switch (no_of_switch_presses) {
case 0:
// *** Welcome Message ***

lcd.setCursor(0,0);//first half of the screen
lcd.print(“Damien’s”);

lcd.setCursor(0,1);//second half of the screen
lcd.print(“Project”);

 

// ** TEMPERATURE MODE **
TEMP();

lcd.setCursor(0,0);//first half of the screen
lcd.print(“Temp = “);
lcd.setCursor(0,1);//second half of the screen
delay(200);
lcd.print(TC);//printing the degree celsius value which is going to be called TC.
lcd.setCursor(5,1);//starting after the 5th position on the second half of the screen
lcd.print(“oC “); //degrees celsius

break; // end temperature case

// ** HUMIDITY MODE **
lcd.setCursor(0,0);//first half of the screen
lcd.print(“Humid Val”);

lcd.setCursor(0,1);//second half of the screen
lcd.print(” “);
// print the current humidity value:

break;// end humidity case

LIGHT();
// ** Light Level MODE **
lcd.setCursor(0,0);//first half of the screen
lcd.print(“Lux Val “);
lcd.setCursor(0,1);//second half of the screen
lcd.print(LuxVal);//printing the Lux value from the LIGHT function
delay(200);

break; // end light level case

Week 7 – LCD Bench Test (week 1)

This was one of the more simple weeks, because the LCD board had been given to us we knew there was no problems in the design of the board and the only problems we could run into is if I place a component in the wrong place, which did happen… 😦

I knew I was going to be using the multimeter as a continuity tester in a few weeks so I played around with it a bit on the LCD board just to get the feel for it, and knowing where had to be tested when looking at the PCB layout on the computer too. 

There was a few tests that we had to conduct but it was done easily enough. I had to do a continuity test to ensure that theres no fault in the track between two components, allowing current to flow down and complete the circuit. The power test is to ensure that im getting the correct voltages in the correct places, like IC sockets etc, although there was none on this board.

I did run into one problem, I put a 10k resistor in before the LED which caused it to light up, but very very low amount of light was coming from it, although you could just about see it which was good. I read the resistor backwards because these were 5 band resistors which provide greater accuracy whereas im used to using 3 band resistors.

Week 4 and 5 – Manufacture of Sensor and Control board and LCD Shield

This is the week where we started actually making our own PCB boards, if theres any faults with the board now, its our own fault as its our own design.. We didnt have to worry about the LCD board not working, as that was given to us so we knew it worked, I suppose I had to trust Ray on this one 😀

The Manufacture of the sensor and control board involved a number of steps. First of all, I had to print the artwork that would be put onto some one sided fibreglass PCB board, peeled the protective layer off the PCB, and then put it in the sealed UV light machine to print the artwork onto the physical board. When this was done, the board was then put into a number of tanks.

Tank 1:

Developing – this tank removes the UV sensitive chemicals from the board. This will leave something like a stencil on the board thats in the shape of my original design.

Tank 2:

Etching – This tank removes the copper wherever the ‘stencil’ isint protecting it. After this process is done, we can now see all the different electrical connections that make the circuit.

Tank 3:

Photoresist Stripping – The photo resist is now removed off the copper tracks that are on the board.

Tank 4:

Tinning – Because copper tracks are now visible, a protective layer has to be put on the copper tracks otherwise they would oxidise, making them unusable.

Board in process of being manufactured

 

Next was assembly of the boards, placing the components and soldering them into the correct spot for them. Because this was such a time consuming thing to do, it took both weeks 4 and 5 to do, but I didnt mind because I wanted it to work correctly the first time so did not want to rush it.

Week 6 – Algorithms!

Lets be honest, nobody likes algorithms, right??

This week I had to make 2 algorithms.

• LCD Switch Menu algorithm
• Temperature reading algorithm

The LCD Switch Menu one was easy enough and very straight forward, but the temperature reading ones were a bit more difficult.

My two algorithms are displayed below:

LCD Switch Menu Algorithm

Because the algorithm was so long, I snipped it in half and zoomed in on each so its easier to read.

Temperature reading Algorithm