heltec GPS

heltecGPS.ino

#include <Wire.h>  // Only needed for Arduino 1.6.5 and earlier
#include "SSD1306.h" // alias for `#include "SSD1306Wire.h"`
#define SDA    4
#define SCL   15
#define RST   16 //RST must be set by software
#define DISPLAY_HEIGHT 64
#define DISPLAY_WIDTH  128

SSD1306  display(0x3c, SDA, SCL, RST);
float speed_kmh = 0.0;
int satellites_num = 0;

// The TinyGPS++ object
#include <TinyGPS++.h>
TinyGPSPlus gps;


// Adapted from Adafruit_SSD1306
void drawRect(void) {
  for (int16_t i=0; i<DISPLAY_HEIGHT/2; i+=2) {
    display.drawRect(i, i, DISPLAY_WIDTH-2*i, DISPLAY_HEIGHT-2*i);
    display.display();
    delay(20);
  }
}


void setup() {
  // gps init
  Serial.begin(9600);
  
  // display init
  delay(200); 
  display.init();
//  display.flipScreenVertically();
  display.setFont(ArialMT_Plain_24);
  display.setTextAlignment(TEXT_ALIGN_CENTER);
  
  drawRect();
  display.display();
  delay(100);
  display.clear();
  display.drawString(64,15, "Hello!");
  display.display();
  delay(500);
  display.clear();
  display.display();
  updateDisplay();
}
bool onoff = false;

char * TimeToString(int h, int m, int s){
 static char str[12];
 sprintf(str, "%02d:%02d:%02d", h, m, s);
 return str;
}

char * FormatSpeed(){
  static char str[3];
  dtostrf(speed_kmh, 1, 1, str);
  if (speed_kmh < 10){
    sprintf(str, "0%s", str);
  }
  return str;
}

void updateDisplay(){
  display.clear();
  if (onoff) display.drawRect(1, 1, DISPLAY_WIDTH-2, DISPLAY_HEIGHT-2);
  
  display.setTextAlignment(TEXT_ALIGN_CENTER);
  display.setFont(ArialMT_Plain_16);
  display.drawString(64,3, "sats: " +String(satellites_num));

  
  display.drawString(64,42, TimeToString(gps.time.hour(), gps.time.minute(), gps.time.second()));
  
  display.setFont(ArialMT_Plain_24);
  display.drawString(64,15, FormatSpeed()+String("kph"));
  
  display.display();
  delay(20);
}

void loop() {
  
  while (Serial.available() > 0) {  
    if (gps.encode(Serial.read())){
      onoff = !onoff;
      satellites_num = gps.satellites.value();
      speed_kmh = gps.speed.kmph();
      updateDisplay();
    }
  }
}