ASSIGNMENT

• Add an output device to a microcontroller board you've designed and program it to do something

Preperation

This is week assignment is to make a microcontroller board which can be used to contol an output device. There are different type of output devices are available like LED, Speakers,LED arrays, RGB LED, LCD,OLED,Servo & steppr motors etc. I have decided to make a contol board to interface with LCD and OLED. Actually for my final project, i need to display the measurement values for that my intitial planning is to use LCD as the display but the size of it is big, So i am planning to make it on OLED display. I thought this week will try the two displays , gone through the basics of LCD and OLED displays and the datasheet.

Multi Interface Board(MI Board)

I planned to make display contol board, especially for LCD and OLED display based on Attiny44 Microcontroller, Later i planned to brought some free pins to connectors so that i can control some more devices and named my circuit as Multiinterface board. Using the board we can interface LCD, OLED, Servos directly & by adding another driving board we can interface steppers and spaekers. My board block schematic is shown below.

Design of MI board

The board design i have done based on Neil's LCD board. This week i tried Kicad software for designing the board because in the electronics design week i have tried Kicad and interested to do something for my assignments. Started my boards design in Kicad schematic editor, First i downloaded and added the Fab libraries into the kicad libraries Fab library. Download the file,unzip it and add the ".lib" file to through componenet libraries option from the preference menu , Also i have gone through some video tutorials on designing usig Kicad. We can place the componenets using "place component" option from the right side of the toolbar.

Actually as told earlier , My board is having some more circuits included a sensing circuit for the resistance value measurements and a voltage regulator circuit for standalone operation of the board. After placing all the componenets, connected the componenets each section and completed the schematic of my board. Next i have done the ERC checks and it showed some errors like opened connections etc., corrected those errors and the below showed image is the final schematic of my Multi Interface board.

Next is to add componenet footprints, Once the schmatic is over we can add the foot prints of the components by "Run Cvpcb" button on the top menu. I have added the following footprints to my board. After completing the step we can save the netlist and close the window. Again from the schematic editor generate the netlist using "Generate netlist" button and save into the directory.

Next step is to routing the layout of my pcb, We can select Run pcbnew button in the schematic editor for this. Once clicked the new window will come and we can import the netlist saved into the directory and open it. We have to first set the design rules from the "design rules" menu. My design rule setting for the multi control board is shown here.

Set the desgn rules and we can do manual routing. It's one of the hardest part i have faced in this week, eventhough i enjoyed it. completed the layout routing and is shown below. This is a single side pcb and the red lines are the traces and the yellow lines are dimension lines.

After the completion we can export the layout to ".SVG" format. First we need a file for milling the pcb and second one for cutting the board. The settings for the mill and cutout are shown below.

# Resistance Meter Program
#include 
LiquidCrystal lcd(5,4,3,2,1,0);

int analogPin= 6;
int raw= 0;
int Vin= 5;
float Vout= 0;
float R1= 10000;
float R2= 0;
float buffer= 0;

void setup()
{
lcd.begin(16, 2);
}

void loop()
{
raw= analogRead(analogPin);
if(raw)
{
buffer= raw * Vin;
Vout= (buffer)/1024.0;
buffer= (Vin/Vout) -1;
R2= R1 * buffer;

lcd.setCursor(0, 0);
lcd.print("Vout: ");
lcd.print(Vout);

lcd.setCursor(0, 1);
lcd.print("R2: ");
lcd.print(R2);
delay(1000);
}
}