Synchronous Serial Communication!

Using an OLED screen is a very simple and easy way to get information out to a user. As part of this lab we had to communicate with this screen via I2C, which is a

Figure 1. Breadboard view of a potentiometer and an SSD1306 OLED screen attached to a Nano 33 IoT. The potentiometer is connected to pin A0. The screen’s SDA pin is connected to pin A4 and the SCL pin is connected to pin A5.

Using this example below, I was able to get the OLED screen to show me what the sensor value was reading. While we did this in a prior week using p5, this turned out to be a very visually pleasing method of showing off the same information.

/*
  Minimal example for SSD1306 OLED display
  manufacturer's site: <http://www.solomon-systech.com/en/product/advanced-display/oled-display-driver-ic/ssd1306/>
  datasheet: <https://www.crystalfontz.com/controllers/SolomonSystech/SSD1306/339/>
  library: <http://librarymanager/All#Adafruit_SSD1306>
  These displays are common and inexpensive online, and require only the
  I2C pins (SDA and SCL) from an Arduino. The Adafruit library works well with them.
  This example reads the millis() and ana analog sensor and displays both.
  It's written for a 128x64 display, but can be modified to fit a 128x32 display as well.
  Change the SCREEN_HEIGHT to change displays, and adjust font sizes and cursor locations
  to suit your application.
  created 4 Oct 2021
  by Tom Igoe
  based on the Adafruit_SSD1306 library examples
*/

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

const int SCREEN_WIDTH = 128; // OLED display width, in pixels
const int SCREEN_HEIGHT = 64; // OLED display height, in pixels

// initialize the display:
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT);

int xPos = 0;
void setup() {
  // initialize serial and wait 3 secs for serial monitor to open:
  Serial.begin(9600);
  if (!Serial) delay(3000);
  // first parameter of begin() sets voltage source.
  // SSD1306_SWITCHCAPVCC is for 3.3V
  // second parameter is I2C address, which is
  // 0x3C, or 3D for some 128x64 modules:
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("Display setup failed");
    while (true);
  }
  Serial.println("Display is good to go");
  // clear the display:
  display.clearDisplay();
}

void loop() {
  int sensorReading = analogRead(A0);
  int graphHeight = SCREEN_HEIGHT - map(sensorReading, 0, 1023, 0, SCREEN_HEIGHT);
  display.drawLine(xPos, SCREEN_HEIGHT, xPos, graphHeight, SSD1306_WHITE);
  xPos++;
  if (xPos > SCREEN_WIDTH) {
    xPos = 0;
    // clear the display:
    display.clearDisplay();
  }

  // push everything out to the screen:
  display.display();
}

OLED pot.mov

What was interesting about this video too is the shutter speed of the camera was slightly out of sync with the refresh rate of the LED and so we see this underlying pattern emerge on the screen itself!

The other part of this lab was playing around with SPI communication! For this I referred back to my fish project which made use of SPI via the