the-cup/the-cup.ino

/* Pin layout used:
 * -----------------------------------------------------------------------------------------
 *             MFRC522      ESP32C6
*             Reader/PCD    Feather
 * Signal      Pin          Pin
 * -----------------------------------------------------------------------------------------
 * SPI SS 1    SDA(SS)      SDA/4
 * SPI SCK     SCK          SCK
 * SPI MOSI    MOSI         MOSI
 * SPI MISO    MISO         MISO
 *
 */

#include <WiFiManager.h> // https://github.com/tzapu/WiFiManager
#include <HTTPClient.h>

#include <MFRC522v2.h> // https://github.com/OSSLibraries/Arduino_MFRC522v2
#include <MFRC522DriverSPI.h>
#include <MFRC522DriverPinSimple.h>
#include <MFRC522Debug.h>

#include "Adafruit_MAX1704X.h"


#define SS_PIN SDA
#define SLEEP_DURATION 1

#define RGB_BRIGHTNESS 4 // Change neopixel brightness (max 255)

MFRC522DriverPinSimple ss_1_pin(SS_PIN); // Configurable, take an unused pin, only HIGH/LOW required, must be different to SS 2.
MFRC522DriverSPI driver_1{ss_1_pin};
MFRC522 reader{driver_1};   // Create MFRC522 instance.

RTC_DATA_ATTR int nbCycles = 0;

Adafruit_MAX17048 lipo;

const char *rootCACertificate = R"string_literal(
-----BEGIN CERTIFICATE-----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=
-----END CERTIFICATE-----
)string_literal";

void read_card(char reader_uid[]);
void send_uid(char reader_uid[]);

void setup() {
  #ifdef DEBUG
    Serial.begin(115200);
    while (!Serial) delay(10);
    Serial.print("Nb cycles: ");
    Serial.println(nbCycles++);
  #endif

  measureBattery();

  reader.PCD_Init(); // Init each MFRC522 card.
  #ifdef DEBUG
    MFRC522Debug::PCD_DumpVersionToSerial(reader, Serial);	// Show details of PCD - MFRC522 Card Reader details.
  #endif
}

void loop() {
  if (reader.PICC_IsNewCardPresent() && reader.PICC_ReadCardSerial()) {
    char reader_uid[32] = "";
    readCard(reader_uid);
    sendUid(reader_uid);
  }
  else {
    delay(200);
    ESP.deepSleep(SLEEP_DURATION * 1000000);
  }
}

void measureBattery() {
  if (nbCycles % 10) {
    lipo.begin();
    if (lipo.cellVoltage() < 2.6) {
      displayError();
    }
  }
}

void readCard(char reader_uid[]) {
  reader.PICC_HaltA();
  reader.PCD_StopCrypto1();
  byte_to_string(reader.uid.uidByte, 4, reader_uid);
  #ifdef DEBUG
    Serial.println(reader_uid);
  #endif
  displaySuccess();
}

void sendUid(char reader_uid[]) {
  connectToWifi();
  postUid(reader_uid);
}

void connectToWifi() {
  WiFiManager wm;
  bool res;
  res = wm.autoConnect("KLUK"); // password protected ap

  if(!res) {
    #ifdef DEBUG
      Serial.println("Failed to connect");
    #endif
    displayError();
    // ESP.restart();
  } 
  else {
    //if you get here you have connected to the WiFi    
    #ifdef DEBUG
    Serial.println("connected...yeey :)");
    #endif
  }
}
void postUid(char reader_uid[]) {
  NetworkClientSecure *client = new NetworkClientSecure;
  client->setCACert(rootCACertificate);
  HTTPClient https;
  #ifdef DEBUG
    Serial.print("[HTTPS] begin...\n");
  #endif
  // configure traged server and url
  https.begin("https://mood.robiweb.net/rfid_tags");  // HTTP
  https.addHeader("Content-Type", "application/json");

  // start connection and send HTTP header and body
  int httpCode = https.POST("{\"identifier\":\"" + String(reader_uid) + "\"}");
  #ifdef DEBUG
    Serial.print("httpCode: ");
    Serial.println(httpCode);
  #endif

  if (httpCode > 0) {
    if (httpCode == HTTP_CODE_CREATED) {
    } else {
      #ifdef DEBUG
        Serial.println("Remote error while sending uid");
      #endif
      displayError();
    }
  } else {
      #ifdef DEBUG
        Serial.print("Remote error while sending uid");
      #endif
      displayError();
  }

  https.end();
  #ifdef DEBUG
    Serial.print("[HTTPS] ended...\n");
  #endif
}

void byte_to_string(byte array[], unsigned int len, char buffer[]) {
  for (unsigned int i = 0; i < len; i++)
  {
    byte nib1 = (array[i] >> 4) & 0x0F;
    byte nib2 = (array[i] >> 0) & 0x0F;
    buffer[i*2+0] = nib1  < 0xA ? '0' + nib1  : 'A' + nib1  - 0xA;
    buffer[i*2+1] = nib2  < 0xA ? '0' + nib2  : 'A' + nib2  - 0xA;
  }
  buffer[len*2] = '\0';
}

void displayError() {
  rgbLedWrite(RGB_BUILTIN, RGB_BRIGHTNESS, 0, 0);  // Red
  delay(1000);
}

void displaySuccess() {
  rgbLedWrite(RGB_BUILTIN, 0, RGB_BRIGHTNESS, 0);  // Green
  delay(1000);
}