PointofSale.ino

/**
 *  Flux Capacitor PoS Terminal - a point of sale terminal which can accept bitcoin via lightning network
 *  
 *
 *  Epaper PIN MAP: [VCC - 3.3V, GND - GND, SDI - GPIO23, SCLK - GPIO18, 
 *                   CS - GPIO5, D/C - GPIO17, Reset - GPIO16, Busy - GPIO4]
 *                   
 *  Keypad Matrix PIN MAP: [GPIO12 - GPIO35]
 *
 *  LED PIN MAP: [POS (long leg) - GPIO15, NEG (short leg) - GND]
 *
 */

 
#include <WiFiClientSecure.h>

#include <ArduinoJson.h> //Use version 5.3.0!
#include <GxEPD2_BW.h>
#include <qrcode.h>
#include <string.h>

#include <Keypad.h>

#include <Fonts/FreeSansBold18pt7b.h>
#include <Fonts/FreeSansBold9pt7b.h>
#include <Fonts/FreeSansBold12pt7b.h>


GxEPD2_BW<GxEPD2_154, GxEPD2_154::HEIGHT> display(GxEPD2_154(/*CS=5*/ SS, /*DC=*/ 17, /*RST=*/ 16, /*BUSY=*/ 4));

char wifiSSID[] = "YOUR-WIFI";
char wifiPASS[] = "YOUR-WIFI-PASS";

const char* host = "api.opennode.co";
const int httpsPort = 443;
String amount = ""; 
String apikey = "YOUR-API-KEY-FROM-OPENNODE-GOES-HERE";
String description = "FLUX"; //invoice description
String hints = "false"; 
String on_currency = "BTCGBP"; //change to your currency ie BTCUSD, BTCEUR, etc
String price;

String data_lightning_invoice_payreq = "";
String data_status = "unpaid";
String data_id = "";
int counta = 0;


//Set other Arduino Strings used
String setoffour = "";
String right = "";
String third = "";
String fourth = "";
String tempfourhex = "";
String line = "";
String line2 = "";
String doublelines = "";
String finalhex = "";
String hexvalues = "";
String result = "";
String PAYMENT = ""; 
String PAYMENTPAID = "true"; 
String response;

//Buffers for Arduino String conversions
char fourbuf[5];
char fourbuff[5];
int tamp = 0;

//Char for holding the QR byte array
unsigned char PROGMEM singlehex[4209];

//Char dictionary for conversion from 1s and 0s
char ref[2][16][5]={
{"0000","0001","0010","0011","0100","0101","0110","0111","1000","1001","1010","1011","1100","1101","1110","1111"},
{"0",   "1",   "2",   "3",   "4",   "5",   "6",   "7",   "8",   "9",   "a",   "b",   "c",   "d",   "e",   "f"}
};

//Set keypad
const byte rows = 4; //four rows
const byte cols = 3; //three columns
char keys[rows][cols] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
byte rowPins[rows] = {12, 14, 27, 26}; //connect to the row pinouts of the keypad
byte colPins[cols] = {25, 33, 32}; //connect to the column pinouts of the keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, rows, cols );
int checker = 0;
char maxdig[20];



void setup() {

display.init(115200);

  display.firstPage();
  do
  {
  display.setRotation(1);  
  display.fillScreen(GxEPD_WHITE);
  display.setFont(&FreeSansBold12pt7b);
  display.setTextColor(GxEPD_BLACK);
  display.setCursor(0, 80);
  display.println("Loading :)");
  }
  while (display.nextPage());{
  }

  
Serial.begin(115200); 
           
  WiFi.begin(wifiSSID, wifiPASS);   
  while (WiFi.status() != WL_CONNECTED) {
     Serial.println("connecting");
     delay(100);
     }
     
  Serial.println("connected");

  pinMode(19, OUTPUT);

  ONprice();

}

void loop() {
  
memset(maxdig, 0, 20);
checker = 20;
int counta = 0;

hexvalues = "";


while (*maxdig == 0){
 keypadamount();
 amount = String(maxdig);
}

fetchpayment(amount);

  qrmmaker(data_lightning_invoice_payreq);

     for (int i = 0;  i < line.length(); i+=4){      
        int tmp = i; 
        setoffour = line.substring(tmp, tmp+4); 
       
             for (int z = 0; z < 16; z++){
               if (setoffour == ref[0][z]){
                hexvalues += ref[1][z];
               }
             }
      }

  line = "";

//for loop to build the epaper friendly char singlehex byte array image of the QR
  for (int i = 0;  i < 4209; i++){
     int tmp = i;   
     int pmt = tmp*2; 
     result = "0x" + hexvalues.substring(pmt, pmt+2) + ",";
     singlehex[tmp] = (unsigned char)strtol(hexvalues.substring(pmt, pmt+2).c_str(), NULL, 16);
  }

  

  display.firstPage();
  do
  {
  display.setPartialWindow(0, 0, 200, 200);
  display.fillScreen(GxEPD_WHITE);
  display.drawBitmap( 7, 7, singlehex, 184, 183, GxEPD_BLACK); 
  
  }
  while (display.nextPage());{
  }

 
  checkpayment(data_id);
 while (counta < 30){
  if (data_status == "unpaid"){
    delay(1000);
   checkpayment(data_id);
   counta++;
  }
  else{
  digitalWrite(19, HIGH);
  delay(4000);
  digitalWrite(19, LOW);
  delay(500);
  counta = 30;
    }  
  }
  counta = 0;
  

}


// QR maker function
void qrmmaker(String xxx){

int str_len = xxx.length() + 1; 
char xxxx[str_len];
xxx.toCharArray(xxxx, str_len);


    QRCode qrcode;
    uint8_t qrcodeData[qrcode_getBufferSize(11)];
    qrcode_initText(&qrcode, qrcodeData, 11, 0, xxxx);
  

    int une = 0;
    
    line = "";

    for (uint8_t y = 0; y < qrcode.size; y++) {

        // Each horizontal module
        for (uint8_t x = 0; x < qrcode.size; x++) {
          line += (qrcode_getModule(&qrcode, x, y) ? "111": "000");
        }
        line += "1";
        for (uint8_t x = 0; x < qrcode.size; x++) {
          line += (qrcode_getModule(&qrcode, x, y) ? "111": "000");
        }
        line += "1";
        for (uint8_t x = 0; x < qrcode.size; x++) {
          line += (qrcode_getModule(&qrcode, x, y) ? "111": "000");
        }
        line += "1";    
    }
}





//Function for keypad
void keypadamount(){

display.firstPage();
  do
  {
  display.setRotation(1);
  display.fillScreen(GxEPD_WHITE);
  display.setFont(&FreeSansBold12pt7b);
  display.setTextColor(GxEPD_BLACK);
  display.setCursor(20, 20);
  display.println("Amount then #");
  display.println();
  display.println("Sats: ");
  display.println(on_currency.substring(3) + ": ");
  display.setFont(&FreeSansBold9pt7b);
  display.println(" Press * to clear");

  }
  while (display.nextPage());{
  }

  while (checker < 20){
  
   char key = keypad.getKey();
   
   if (key != NO_KEY){
   String virtkey = String(key);
   
   if (virtkey == "*"){
    memset(maxdig, 0, 20);
    checker = 20;
   }
    
   if (virtkey == "#"){

     display.firstPage();
     do
     {
     display.setRotation(1);
     display.setPartialWindow(0, 0, 200, 200);
     display.fillScreen(GxEPD_WHITE);
     display.setFont(&FreeSansBold12pt7b);
     display.setTextColor(GxEPD_BLACK);
     display.setCursor(20, 20);
     display.println("Processing...");

     }
     while (display.nextPage());{
     }
    Serial.println("Finished");
    checker = 20;
   }
   else{
  
    maxdig[checker] = key;
    checker++;
    Serial.println(maxdig);


    showPartialUpdate(maxdig);
   }
   }

  }
  checker = 0;
}




void showPartialUpdate(String satoshisString)
{
  float fiat = price.toFloat();
  float sats = satoshisString.toFloat();

  float fiatscum = sats / 100000000 * fiat;

  
  display.firstPage();
  do
  {
  display.setRotation(1);
  display.setFont(&FreeSansBold12pt7b);
  display.setTextColor(GxEPD_BLACK);

 // display.fillRect(box_x, box_y, box_w, box_h, GxEPD_WHITE);
  display.setPartialWindow(60, 65, 120, 20);
  display.setCursor(60, 81);
  display.print(satoshisString); 

  }
  while (display.nextPage());{
  }
  display.firstPage();
  do
  {
  display.setRotation(1);
  display.setFont(&FreeSansBold12pt7b);
  display.setTextColor(GxEPD_BLACK);

 // display.fillRect(box_x, box_y, box_w, box_h, GxEPD_WHITE);
  display.setPartialWindow(60, 90, 120, 20);
  display.setCursor(60, 106); 
  display.print(fiatscum); 

  }
  while (display.nextPage());{
  }

  
}


///////////////////////////// GET/POST REQUESTS///////////////////////////


void ONprice(){
  WiFiClientSecure client;

  if (!client.connect(host, httpsPort)) {

    return;
  }



  String url = "/v1/rates";


  client.print(String("GET ") + url + " HTTP/1.1\r\n" +
               "Host: " + host + "\r\n" +
               "User-Agent: ESP32\r\n" +
               "Connection: close\r\n\r\n");

  while (client.connected()) {

     String line = client.readStringUntil('\n');
    if (line == "\r") {

      break;
    }
  }
  String line = client.readStringUntil('\n');
  
    const size_t capacity = 169*JSON_OBJECT_SIZE(1) + JSON_OBJECT_SIZE(168) + 3800;
    DynamicJsonDocument doc(capacity);

    deserializeJson(doc, line);

String temp = doc["data"][on_currency][on_currency.substring(3)]; 
price = temp;
Serial.println(price);


}



void fetchpayment(String SATSAMOUNT){


  WiFiClientSecure client;

  if (!client.connect(host, httpsPort)) {

    return;
  }

  String topost = "{  \"amount\": \""+ SATSAMOUNT +"\", \"description\": \""+ description  +"\", \"route_hints\": \""+ hints  +"\"}";
  String url = "/v1/charges";

   client.print(String("POST ") + url + " HTTP/1.1\r\n" +
                 "Host: " + host + "\r\n" +
                 "User-Agent: ESP32\r\n" +
                 "Authorization: " + apikey + "\r\n" +
                 "Content-Type: application/json\r\n" +
                 "Connection: close\r\n" +
                 "Content-Length: " + topost.length() + "\r\n" +
                 "\r\n" + 
                 topost + "\n");

  while (client.connected()) {
    String line = client.readStringUntil('\n');
    if (line == "\r") {

      break;
    }
  }
  String line = client.readStringUntil('\n');

  
    const size_t capacity = 169*JSON_OBJECT_SIZE(1) + JSON_OBJECT_SIZE(168) + 3800;
    DynamicJsonDocument doc(capacity);

    deserializeJson(doc, line);

    String data_idd = doc["data"]["id"]; 
    data_id = data_idd;
    String data_lightning_invoice_payreqq = doc["data"]["lightning_invoice"]["payreq"];
    data_lightning_invoice_payreq = data_lightning_invoice_payreqq;
}




void checkpayment(String PAYID){

  WiFiClientSecure client;

  if (!client.connect(host, httpsPort)) {

    return;
  }

  String url = "/v1/charge/" + PAYID;


  client.print(String("GET ") + url + " HTTP/1.1\r\n" +
               "Host: " + host + "\r\n" +
               "Authorization: " + apikey + "\r\n" +
               "User-Agent: ESP32\r\n" +
               "Connection: close\r\n\r\n");


  while (client.connected()) {

    
    String line = client.readStringUntil('\n');
    if (line == "\r") {
      break;
    }
  }
  String line = client.readStringUntil('\n');


  
const size_t capacity = JSON_OBJECT_SIZE(1) + JSON_OBJECT_SIZE(2) + JSON_OBJECT_SIZE(4) + JSON_OBJECT_SIZE(14) + 650;
 DynamicJsonDocument doc(capacity);

    deserializeJson(doc, line);

String data_statuss = doc["data"]["status"]; 
data_status = data_statuss;
Serial.println(data_status);
}