Board Design and soldering

Initially I designed my board using an ATTiny 44 mincrocontroller. I connected a 4 pin header to be used for connecting to the I2C module. In ATTiny 44, the SDA and SCL pins are on pin number 7 and 9 (PA6 and PA4) respectively. These pins are also used for connecting the MOSI and SCK for AVRISPSMD programmer header connection. Since, I am using AVRISPSMD programmer header for programming my board, I used a slide switch to switch the functionality of the pins as require. Aside from that, I added 2 LED (one as power LED, and one test LED to check if my board is workig). I printed the board, soldered all the conponents and connected my board to the I2C_LCD module.



When programming the board for LCD display, I needed to download a separate library for I2C_LCD module named LiquidCrystal I2C. I downloaded the library from the arduino site https://www.arduino.cc/reference/en/libraries/liquidcrystal-i2c/.
Then I started with the programming but I found that the wire.h library which is available in the Arduino IDe doesn't work for AVR Tiny microcontrollers and I need to add a seperate library called TinywireM.h. I downloaded this library from this site https://www.arduino.cc/reference/en/libraries/tinywirem/ . I then loaded the code to display a text and after many trials and failures, I finally succeeded in compiling and loadiung the program to my board. However, the display was nowhere to be seen. I thought maybe the LCD was broken, so to test it, I connected the LCD to arduino UNO board and loaded the same program, and WOALA!! it worked. So then, I consulted with my local instructor and he shared that similar issues were faced by other students who were using ATTiny 44 for as a microcontroller. Thus, I had to created an entirely new board for the week.

Since the ATTiny44 microcontroller failed to work for me, I started to design my board using ATMega328p. I choose this specific microcontroller because I am using the same for my final project board. Similar to how I designed my earier board, I added the following components to my board;

1. One 4-pin header for I2C module;
2. One 2*3 pin header for my AVRISPSMD programmer;
3. One 6-pin header for FTDI connector;
4. One 20Mhz resonator;
5. One RESET switch;
6. 2 LEDS(one for power and one for testing)
7. One capacitor

I used MITMods to created the .rml file for my board design and then milled using Roland SRM-20 machine. I then soldered the components and checked the connection using multimeter.

Final soldered board

Programming

After I was done with checking all the connections, I tested my board with a simple blink porgram. The test was successful so, I began with connecting my board to the I2C_LCD module and programming the board to display a simple text. However, I encountered an issue. Initially when I used the ATTiny44 microcontroller board, I had to replace the wire.h library with TinywireM.h library. I had to undo this to make the program functional for the ATMega328p board. Thus, I deleted the TinywireM.h library and replaced it with wire.h library in the arduino library folder.

Next, I tried to load a simple display program to my board but I found that I had to find find the address of the I2C module. To do that I selected the I2C scanner program under the example provided in the Arduino IDE.

I compiled and loaded the program and checked the out put on the serial monitor under the tools option. The Address for the I2C was 0x27.

I added the I2C address in the program for displaying a text.

I loaded the porgram and it finally worked.