StmPong

1   Description

A Simple Multiplayer Game Console to play Ping-Pong. The STM is connected to an OLED display to track the movements of the ball which utilizes concepts of I2C and Timers. The communication between the two devices is established using ESP8266 which communicates with the STM using UART. The ESP8266 solely handles Wi-Fi connectivity to synchronize OLED displays, ensuring both consoles show identical game states. One ESP8266 will act as an access point and the other will connect to this acting as a client. The button status and Game state will be communicated between the to STM using this connection.

2   Components Required

• Stm32discovery board
• Esp01 module
• SSD1306 OLED display
• Buzzer
• Game console PCB
• Push Buttons
• MOSFET
• 3 x 10k Resistors

3   Functional Block Diagram

4   Connection Table

OLED	STM32
VCC	3.3 V
SDA	PB11(SDA)
SCL	PB13 (SCL)
GND	GND

ESP01	STM32
VCC	3.3 V
ESP_RX	PC4(USART3_TX)
ESP_TX	PC5(USART3_RX)
ENABLE	3.3V
GND	GND

BUZZER	STM32
+ive	PB2
-ive	GND

Buttons	STM32
Button 1	PA4
Button 2	PA5
Button 3	PA6
Button 4	PA7

5   Built-in Peripherals

Peripheral	Function
USART3	It's used to communicate STM32 with PC
USART1	It's used for communication between STM32 and ESP01
I2C	It's used to interface STM32 with OLED
EXTI	Interrupts triggered on button clicks
Timers	Timer is set at 30 HZ setting the refresh rate of the OLED to 30 fps and used to synchronise all the activities in the oled with the stm board

6   Milestones

	Milestones Achieved
Milestone 1	A custom PCB will be designed to hold the OLED display, ESP8266 and the buttons. This PCB Design will be shown as Milestone 1 and will be fabricated once it is reviewed by the TA.
Milestone 2	Interfacing the OLED display using I2C and displaying a simple object to make sure the display connection is properly established. Interfacing ESP8266 with STM32 and establishing a simple connection between two STMs. Making sure a switch from one STM toggles the LED on the second STM to make sure the connection is established. Interfacing all the buttons using interrupts.
Milestone 3	Creating the required ball motion in the oled display. Making the paddle move when the button is pressed accordingly. Creating a simple menu to connect to another device and start the game.
Milestone 4	Completed the game in single-player mode.

7   Implementation

The first step towards the implementation of the project was to interface all the external and internal peripherals associated with the project.

1. The first and hardest part of this phase was interfacing the SSD1306 OLED. We interfaced it using I2C but intially, there were lots of confusion on finding the right addresses since the hardware and datasheet contained different WHO_AM_I addresses. But eventually we figured that out and once we got the addresses right, it was all about writing the logics for the game.
2. The next peripheral we interfaced was the ESP01. Interfacing the ESP module was straight-forward. We read/wrote data using UART. We designed a package which contained all the data to be transmitted (i.e.)position of the ball and paddle, synchronisation timer and all other data required for the game.
3. The other peripherals we implemented were EXTI(triggered by button pushes), Timers(to synchronise ball and paddle movements to button pushes) and GPIOs(buttons and buzzer).
4. To connect all the external peripherals with the STM32 Discovery board, we designed a PCB to house all the components with the board. Once the board was fabricated, we assembled and soldered all the components.
   

8   Challenges faced during implementation

• The OLED's refresh rate was 30 fps but the default firmware of ESP01 had a lower transmission rate which caused data loss, hindering the establishment of WiFi Communication between two consoles.
• The OLED interfacing was challenging to implement.
• The esp01 and oled combined were not able to draw sufficient current to work simultaneously.
• The Buzzer didn't draw enough current from GPIO pins to trigger.

Contributors

Tharnath Bagirathan
Philip Gabriel Johnson
Siddharth Kaushal Manga