Week 11: Networking and Communications

Planted April 14, 2026

Overview

For this week, I focused on I2C communication using a small OLED display. This week was generally about networking 101 and was easy going since I had the fundamentals down

I2C is a two-wire communication protocol used to connect low-speed devices (sensors, displays, etc.) to microcontrollers:

SDA (Serial Data) carries data
SCL (Serial Clock) synchronizes timing

I used a GME12864-7B OLED, the version I didn’t use in the production week

Group Assignment

Connections

VCC -> 5V
GND -> GND
SCL -> GPIO 6
SDA -> GPIO 7

Problem

I had trouble getting the screen to work at first. That was mainly caused by the library I used which was SSD1306’s library. Hence I decided to switch to the U8g2 library which is more universal for i2c oled’s and the problem was fixed.

Connection test image

First I ran a connection test! It worked

#include <Wire.h>
#include <U8g2lib.h>

U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0);

static const unsigned char starfleet_bmp[] PROGMEM = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* ... trimmed for readability ... */ 0x00, 0x00
};

void setup() {
  Wire.begin(6, 7);
  u8g2.begin();
}

void loop() {
  u8g2.clearBuffer();
  u8g2.drawXBMP(0, 0, 128, 64, starfleet_bmp);
  u8g2.sendBuffer();
}

Node usage, displaying a star trek logo

Next to make captain Picard proud I displayed the Star Trek next generation logo on the node.

#include <Wire.h>
#include <U8g2lib.h>

U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0);

#define LOGO_W 16
#define LOGO_H 16

static const unsigned char logo_bmp[] PROGMEM = {
  0x10, 0x00, 0x30, 0x00, 0x28, 0x00, 0x7c, 0x00,
  0x54, 0x00, 0xd6, 0x00, 0xbe, 0x00, 0xba, 0x01,
  0x82, 0x01, 0xf3, 0x01, 0x9b, 0x01, 0x0d, 0x01,
  0x07, 0x03, 0x03, 0x02, 0x01, 0x00, 0x00, 0x00
};

#define NUM_LOGOS 5

struct Logo {
  float x, y;
  float dx, dy;
};

Logo logos[NUM_LOGOS];

void setup() {
  Wire.begin(6, 7);
  u8g2.begin();

  randomSeed(analogRead(0));

  for (int i = 0; i < NUM_LOGOS; i++) {
    logos[i].x = random(0, 128 - LOGO_W);
    logos[i].y = random(0, 64 - LOGO_H);
    logos[i].dx = (random(10, 25) / 10.0) * (random(2) ? 1 : -1);
    logos[i].dy = (random(8, 20) / 10.0) * (random(2) ? 1 : -1);
  }
}

void loop() {
  u8g2.clearBuffer();

  for (int i = 0; i < NUM_LOGOS; i++) {
    u8g2.drawXBMP((int)logos[i].x, (int)logos[i].y, LOGO_W, LOGO_H, logo_bmp);

    logos[i].x += logos[i].dx;
    logos[i].y += logos[i].dy;

    if (logos[i].x <= 0 || logos[i].x >= 128 - LOGO_W) {
      logos[i].dx = -logos[i].dx;
      logos[i].x = constrain(logos[i].x, 0, 128 - LOGO_W);
    }
    if (logos[i].y <= 0 || logos[i].y >= 64 - LOGO_H) {
      logos[i].dy = -logos[i].dy;
      logos[i].y = constrain(logos[i].y, 0, 64 - LOGO_H);
    }
  }

  u8g2.sendBuffer();
  delay(30);
}

Floating star trek logos

Finally, to have some more fun and to make amends with vibe coding version one I made some floating star trek logo’s. Live Long and Prosper!

#include <Wire.h>
#include <U8g2lib.h>

U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0);

static const unsigned char starfleet_bmp[] PROGMEM = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf8, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xbc, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x9c, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1e, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x67, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x67, 0x3c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x63, 0x3c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x63, 0x78, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x61, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x61, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0xe0, 0xe0, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0xe0, 0xe0, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0xf0, 0xc0, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x78, 0xf0, 0xc0, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x38, 0xf0, 0x80, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3c, 0xf0, 0x80, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3c, 0xf0, 0x81, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1c, 0xf0, 0x01, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1e, 0xf0, 0x01, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1e, 0xfe, 0x07, 0x0e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xce, 0xff, 0x3f, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x8f, 0xff, 0x1f, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0xfc, 0x07, 0x1c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xf8, 0x01, 0x3c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0x98, 0x03, 0x3c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x07, 0x0c, 0x03, 0x38, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x03, 0x0c, 0x03, 0x78, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x03, 0x00, 0x00, 0x78, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x03, 0x00, 0x00, 0x78, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x03, 0x00, 0x10, 0x70, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x01, 0x00, 0x7e, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x01, 0x80, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x01, 0xc0, 0xff, 0xe1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x01, 0xf0, 0xe7, 0xe3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x01, 0xf8, 0xc1, 0xe3, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x00, 0xfc, 0x80, 0xe7, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x00, 0x3e, 0x00, 0xef, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x00, 0x1f, 0x00, 0xdf, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0xc0, 0x0f, 0x00, 0xde, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0xe0, 0x07, 0x00, 0xfc, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0xf0, 0x01, 0x00, 0xf8, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0xf8, 0x00, 0x00, 0xf8, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x7c, 0x00, 0x00, 0xf0, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x3c, 0x00, 0x00, 0xe0, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x1e, 0x00, 0x00, 0xe0, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x1f, 0x00, 0x00, 0xc0, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x0f, 0x00, 0x00, 0x80, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x07, 0x00, 0x00, 0x80, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x03, 0x00, 0x00, 0x00, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x01, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

void setup() {
  Wire.begin(6, 7);
  u8g2.begin();
}

void loop() {
  u8g2.clearBuffer();
  u8g2.drawXBMP(0, 0, 128, 64, starfleet_bmp);
  u8g2.sendBuffer();
}

Overall it was an OK week!