Arduino sketch: osh-park-teensy-knob-oled

osh-park-teensy-knob-oled.ino

/*
  AnalogReadSerial modified to write to Adafruit i2c OLED display
  Reads an analog input on pin 0, prints the result to the serial monitor.
  Graphical representation is available using serial plotter (Tools > Serial Plotter menu)
  Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

  This example code is in the public domain.
*/

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

// If using software SPI (the default case):
#define OLED_MOSI   9
#define OLED_CLK   10
#define OLED_DC    11
#define OLED_CS    12
#define OLED_RESET 13
Adafruit_SSD1306 display(OLED_MOSI, OLED_CLK, OLED_DC, OLED_RESET, OLED_CS);


// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC);
 

}

// the loop routine runs over and over again forever:
void loop() {
  char buf[5];
  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  sensorValue = sensorValue & 0xFFF0;
  int mapValue = map(sensorValue, 0, 1008, 0, 128);
  int printValue = map(sensorValue, 0, 1008, 0, 1024);
  // print out the value you read:
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.setTextSize(4);
  sprintf(buf, "%04d", printValue);
  display.println(buf);
  display.fillRect(0, 32, mapValue, 32, 1);
  display.display();
  delay(10);        // delay in between reads for stability
}

Notes from Teensy 3.2 setup on Debianb 9 (Stretch) x86_64:
https://gist.github.com/pdp7/ba2622da1f9223c6f8cd