i2c custom driver

Final project for the Operating Systems 2018/2019 course of prof. Giorgio Grisetti held at Sapienza.

GitHub repo

What

Implementation of custom i2c drivers for Master/Slave the communication between an Arduino and a generic i2c device.

We coded two versions:

1. i2c/basic: i2c communication standard primitives. To test these drivers, two Master/Slave test mains were made between two different ATMegas (code available in the examples/[master/slave] folder).

2. i2c/interrupt: i2c driver made with Interrupt and used in the upper layer comunication.h to enable Multi-Slave communication.

In addition, the driver for a LCD device was realized using the underlying comunication.h layer. The driver allows:

• managing different displays (tested 16x2 and 20x4)
• screen shifting
• custom character creation

As an example of how the serial communication and i2c driver works, we made a video game “loosely inspired” by Pacman.

Master/Slave - 1 : 1	Master/Slave - 1 : n
	my_lcd_i2c
	comunication
i2c/basic	i2c/interrupt

How

Initially, to fully understand how the protocol works, we implemented the Basic version. Later, we realized the version with interrupts and with Multi-slave support (thus with address separation at both hardware and software levels).

We encountered many difficulties in the implementation of nonstandard communication in every piece of hardware, in particular:

• Arduino: reading by disabling interrupts in non-blocking mode
• PC: Opening UART properly and defining primitives for communication
• Display: understanding of low-level screen operation, particularly shift

N.B. The screen is not totally refreshed each time (due to time issues) and a full shift is made to the display. However, the display does not keep an absolute reference of the columns, but changes them with each shift. (Ex. column 3 moves with each shift.)

How to Run

First, compile:

• pc_server
• arduino client and then: ```s cd avr/arduino_client make make arduino_client.hex

cd ../../pc_server make ./i2c_videogame 0 # 0 se device su ttyACMO, 1 se ttyACM1 ```

Now the fun begins

How the game works

The game core is located on Arduino, while user input is handled by the PC keyboard. The communication between Arduino and PC is done via serial port.

Here are the various steps of the game:

1 - At startup the PC waits for the Arduino to be ready; once synchronized the words start will appear on both screens.

2 - Via keyboard the Player data (name and desired difficulty) is entered.

3 - Arduino is independent of the pc, so the game continues even if no keys are pressed on the keyboard. At each refresh step it sends a life or death message to the pc to communicate the status of the game.

4 - When the player dies the score is printed on both screens and Arduino remains waiting for a new game.

Authors

• Francesco Colasante
• Luca Gioffrè
• Gianmarco D’Alessandro
• Alessandro Accardo