I2C (Inter-Integrated Circuit)

I2C (Inter-Integrated Circuit)#

Discover the I2C communication protocol and learn how to communicate with I2C devices using the DualMCU ONE board. This section will cover I2C bus setup and communication with I2C peripherals.

I2C

Fig. 30 I2C Pins#

I2C Overview#

I2C (Inter-Integrated Circuit) is a synchronous, multi-master, multi-slave, packet-switched, single-ended, serial communication bus. It is commonly used to connect low-speed peripherals to processors and microcontrollers. The DualMCU ONE development board features I2C communication capabilities, allowing you to interface with a wide range of I2C devices.

Pinout Details#

Below is the pinout table for the I2C connections on the DualMCU ONE, detailing the corresponding GPIO connections for both the ESP32 and RP2040 microcontrollers.

Table 6 I2C Pinout#

PIN

GPIO ESP32

GPIO RP2040

SCLK

22

5 / 21 / 23

SDA

21

4 / 20 / 22

Scanning for I2C Devices#

To scan for I2C devices connected to the bus, you can use the following code snippet:

import machine

i2c = machine.SoftI2C(0, scl=machine.Pin(5), sda=machine.Pin(4))
devices = i2c.scan()

for device in devices:
    print("Device found at address: {}".format(hex(device)))

SSD1306 Display#

ssd1306 display

Fig. 31 SSD1306 Display#

The display 128x64 pixel monochrome OLED display equipped with an SSD1306 controller is connected using a JST 1.25mm 4-pin connector. The following table provides the pinout details for the display connection.

Table 7 SSD1306 Display Pinout#

Pin

Connection

1

GND

2

VCC

3

SDA

4

SCL

Library Support#

MicroPython#

The dualmcu.py library for MicroPython on ESP32 & RP2040 is compatible with the SSD1306 display controller.

Installation

  1. Open Thonny.

  2. Navigate to Tools -> Manage Packages.

  3. Search for dualmcu and click Install.

for more information, Check the section

Alternatively, download the library from dualmcu.py.

Microcontroller Configuration

SoftI2C(scl, sda, *, freq=400000, timeout=50000)

Change the following line depending on your microcontroller:

For ESP32:

>>> i2c = machine.SoftI2C(freq=400000, timeout=50000, sda=machine.Pin(21), scl=machine.Pin(22))

For RP2040:

>>> i2c = machine.SoftI2C(freq=400000, timeout=50000, sda=machine.Pin(4), scl=machine.Pin(5))

Example Code

import machine
from dualmcu import *

i2c = machine.SoftI2C( scl=machine.Pin(22), sda=machine.Pin(21))

oled = SSD1306_I2C(128, 64, i2c)

oled.fill(1)
oled.show()

oled.fill(0)
oled.show()
oled.text('UNIT', 50, 10)
oled.text('ELECTRONICS', 25, 20)

oled.show()

This code initializes the display, fills the screen with different colors, and displays text.

sda=machine.Pin(*) and scl=machine.Pin(*) should be replaced with the appropriate GPIO pins for your setup.

This version clarifies the structure, pin configurations, library usage, installation instructions, and example code for your project. Adjust the placeholders marked with * in your actual code based on your specific GPIO pin assignments.

C++

The Adafruit_SSD1306 library for Arduino is compatible with the SSD1306 display controller.

Installation

  1. Open the Arduino IDE.

  2. Navigate to Tools -> Manage Libraries.

  3. Search for Adafruit_SSD1306 and click Install.

Description code

The provided Arduino sketch is designed to interface an RP2040 microcontroller with an SSD1306 OLED display using the I2C communication protocol. It begins by including the necessary libraries for controlling the display and initializing serial communication for debugging purposes. The sketch defines constants for the display dimensions and I2C pins (SDA on GPIO 4 and SCL on GPIO 5) and initializes an Adafruit SSD1306 object.

Example Code

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED display TWI (I2C) interface
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_WIDTH   128 // OLED display width, in pixels
#define SCREEN_HEIGHT  64  // OLED display height, in pixels
#define SDA_PIN        4   // SDA pin
#define SCL_PIN        5   // SCL pin

// Declare an instance of the class (specify width and height)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void setup() {
  Serial.begin(9600);

  // Initialize I2C
  Wire.setSDA(4);
  Wire.setSCL(5);
  Wire.begin();
  // Start the OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3C for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }

  // Clear the buffer
  display.clearDisplay();

  // Set text size and color
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);
  display.println(F("UNIT ELECTRONICS!"));
  display.display();  // Show initial text
  delay(4000);        // Pause for 2 seconds
}

void loop() {
  // Increase a counter
  static int counter = 0;

  // Clear the display buffer
  display.clearDisplay();
  display.setCursor(0, 10); // Position cursor for new text
  display.setTextSize(2);   // Larger text size

  // Display the counter
  display.print(F("Count: "));
  display.println(counter);

  // Refresh the display to show the new count
  display.display();

  // Increment the counter
  counter++;

  // Wait for half a second
  delay(500);
}
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