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--- iothings:proiecte:2022sric:voltmeter [2023/06/01 21:51]
eduard.olteanu1505 [Software Description]
+++ iothings:proiecte:2022sric:voltmeter [2023/06/01 23:40] (current)
eduard.olteanu1505
@@ Line 1: / Line 1: @@
-==== Voltmeter ====
+==== Voltmeter with Esp32 ====
 Author: Olteanu Eduard-Florin
 ===== Introduction =====
+The main focus of this project is to be able to accurately measure low-voltage batteries in order to determine whether or not they are still functional.
+Additionally, the user can save the values in a database in order to be easier to remember or review the values at a later time and not measure them again.
 ===== Hardware Description =====
@@ Line 12: / Line 16: @@
   * 16x2 I2C LCD
   * Push Button
+  * Multimeter cables
   * Wires
   * Breadboard
@@ Line 19: / Line 24: @@
 {{ :iothings:proiecte:2022sric:schematic_voltmetru.png?500 |}}
-Dispari
-}
 ===== Software Description =====
+The libraries used are:
+<code>
+#include <Adafruit_ADS1X15.h>
+#include <WiFi.h>
+#include <LiquidCrystal_I2C.h>
+#include <Arduino.h>
+#include <Firebase_ESP_Client.h>
+</code>
+Communication between the ESP 32 and both the ADS1115 and the LCD screen is done through the I2C protocol.
+The button is connected to the GPIO4 pin and is used as a trigger to store in database the value read by the AIN0 pin from the ADS1115.
+WiFi connection:
+<code>
+WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
+Serial.print("Connecting to Wi-Fi");
+while (WiFi.status() != WL_CONNECTED){
+  Serial.print(".");
+  delay(300);
+}
+Serial.println();
+Serial.print("Connected with IP: ");
+Serial.println(WiFi.localIP());
+Serial.println();
+</code>
+Firebase connection:
+<code>
+/* Assign the api key (required) */
+config.api_key = API_KEY;
+/* Assign the RTDB URL (required) */
+config.database_url = DATABASE_URL;
+/* Sign up */
+if (Firebase.signUp(&config, &auth, "", "")){
+  Serial.println("ok");
+  signupOK = true;
+}
+else{
+  Serial.printf("%s\n", config.signer.signupError.message.c_str());
+}
+/* Assign the callback function for the long running token generation task */
+config.token_status_callback = tokenStatusCallback; //see addons/TokenHelper.h
+Firebase.begin(&config, &auth);
+Firebase.reconnectWiFi(true);
+</code>
+Voltage measurement:
+<code>
+adc0 = ads.readADC_SingleEnded(0);
+delay(10);
+volts0 = ads.computeVolts(adc0);
+lcd.clear();
+lcd.setCursor(0, 0);
+lcd.print("ADC0:");
+lcd.print(adc0);
+lcd.setCursor(0, 1);
+lcd.print(volts0);
+lcd.print("V");
+</code>
+Storing the value in the database:
+<code>
+// read the state of the switch/button:
+currentState = digitalRead(BUTTON_PIN);
+if ((lastState == LOW && currentState == HIGH) && Firebase.ready() && signupOK) {
+  sendDataPrevMillis = millis();
+  Serial.print ("time: ");
+  Serial.println (sendDataPrevMillis);
+  entry_path = path + "/" + String(sendDataPrevMillis);
+  // Write an Float number on the database path test/float
+  if (Firebase.RTDB.setFloat(&fbdo, entry_path , volts0)) {
+    Serial.println("PASSED");
+    Serial.println("PATH: " + fbdo.dataPath());
+    Serial.println("TYPE: " + fbdo.dataType());
+  }
+  else {
+    Serial.println("FAILED");
+    Serial.println("REASON: " + fbdo.errorReason());
+  }
+}
+lastState = currentState;
+</code>
+We use millis to store the value in order not to overwrite already known values.
+==== Problems and Improvements ====
+  * One problem that I could not fix is the noise the ADS1115 is getting when reading, even if there is nothing measured the pin reads 0.9V, but that doesn't impact measurements.
+  * An improvement could be to add some other form of identification for the batteries when stored in the database.
+  * Another improvement could be to have a phone application that manages the database for the batteries and also that communicates with the ESP32.
+===== Results =====
+The main use-case of this project is to measure the voltage of batteries.
+{{ :iothings:proiecte:2022sric:20230601_225009.jpg ?700 |}}
-===== Demo =====
+{{ :iothings:proiecte:2022sric:20230601_225034.jpg?700 |}}
+We can see that the value is pretty accurate, only 0.01 error delta.
-===== Conclusion =====
+Also, if the button is pressed the value is stored in the database.
+{{ :iothings:proiecte:2022sric:database_batteries.png?700 |}}
 ===== Bibliography=====
-  * [[https://ocw.cs.pub.ro/courses/iothings/laboratoare/2022/lab3]]
+  * [[https://ocw.cs.pub.ro/courses/iothings/laboratoare/2022/lab4]]
+  * [[https://how2electronics.com/how-to-use-ads1115-16-bit-adc-module-with-esp32/]]
+  * [[https://github.com/mobizt/Firebase-ESP-Client]]
+  * [[https://github.com/adafruit/Adafruit_ADS1X15]]