OLED Exchange Rate Monitor

Create a real-time currency exchange rate display using an ESP32 and an OLED screen, updated daily with the latest rates from an online API.

Aug 5, 2024

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554 views

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2 respects

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Data Collection

Internet Of Things

Tools

Components and supplies

Seeed Studio XIAO ESP32C3

SSD1306 OLED Display

Push Button

ESP32 Wroom

Tools and machines

Solder Iron

cables

PCB

Breadboard, Plastic

Apps and platforms

arduino IDE

Project description

Code

Exchangerates

1#include <WiFi.h>
2#include <HTTPClient.h>
3#include <Adafruit_GFX.h>
4#include <Adafruit_SSD1306.h>
5#include <Wire.h>
6
7// OLED display configuration
8#define SCREEN_WIDTH 128
9#define SCREEN_HEIGHT 64
10#define OLED_RESET     -1
11#define SCREEN_ADDRESS 0x3C
12
13// WiFi credentials
14#define WIFI_SSID "YOUR-SSID"
15#define WIFI_PASS "YOUR-PASSWORD"
16
17Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
18
19// API URL for exchange rates
20String url = "YOUR-URL";
21String json;
22String payload;
23const char* ssid = WIFI_SSID;
24const char* password = WIFI_PASS;
25
26// Buttons and timing configuration
27const int button1 = 2;
28const int button2 = 3;
29const long interval = 86400000;  // 24 hours
30const unsigned long screenOffTimeout = 5 * 60 * 1000;  // 5 minutes
31unsigned long lastButtonPressMillis = 0;
32unsigned long previousMillis = 0;
33unsigned long currentMillis;
34int httpCode;
35int xpos;
36int y = 10;
37int speed = 4;
38int highscrolllimit = 2;
39int downscrolllimit = SCREEN_HEIGHT - 2572;
40int pos;
41int lastNewline;
42int secondLastNewline;
43int lineCount = 0;
44int startIndex = 0;
45int numberoflines = 163;
46bool btn1State;
47bool btn2State;
48
49HTTPClient http;
50
51void setup() {
52    Serial.begin(115200);
53    pinMode(button1, INPUT_PULLUP);
54    pinMode(button2, INPUT_PULLUP);
55    if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
56        Serial.println(F("SSD1306 allocation failed"));
57        for (;;);
58    }
59    display.setTextSize(1);
60    display.setTextColor(SSD1306_WHITE);
61    display.display();
62}
63
64void loop() {
65    display.setTextSize(1);
66    btn1State = digitalRead(button1);
67    btn2State = digitalRead(button2);
68    currentMillis = millis();
69
70    // Update the last button press time if any button is pressed
71    if (btn1State == LOW || btn2State == LOW) {
72        lastButtonPressMillis = currentMillis;
73    }
74
75    // Turn off the display if the screen off timeout is reached
76    if (currentMillis - lastButtonPressMillis >= screenOffTimeout) {
77        display.ssd1306_command(SSD1306_DISPLAYOFF);
78    } else {
79        display.ssd1306_command(SSD1306_DISPLAYON);
80
81        // Scroll up if button1 is pressed and not at the limit
82        if (btn1State == LOW && y < highscrolllimit) {
83            y += speed;
84        }
85
86        // Scroll down if button2 is pressed and not at the limit
87        if (btn2State == LOW && y > downscrolllimit) {
88            y -= speed;
89        }
90
91        // Perform an HTTP request at the specified interval or on the first run
92        if (currentMillis - previousMillis >= interval || previousMillis == 0) {
93            if (httpGETRequest()) {
94                previousMillis = currentMillis;
95            } else {
96                // Display "Retrying..." for HTTP or connection errors
97                Serial.println("Retrying...");
98                display.clearDisplay();
99                display.setCursor(0, 0);
100                display.println("Retrying...");
101                display.display();
102                delay(1000);
103            }
104        }
105
106        // Display the payload only if httpGETRequest() was successful and no site error occurred
107        if (httpCode > 0 && !isSiteError(payload)) {
108            display.clearDisplay();
109            display.setCursor(0, y);
110            display.println(payload);
111            display.display();
112        }
113    }
114}
115
116// Function to connect to WiFi
117void connectToWiFi() {
118    Serial.print("Connecting to WiFi network...");
119    display.clearDisplay();
120    display.setCursor(0, 0);
121    display.print("Connecting to WiFi...");
122    display.display();
123
124    WiFi.begin(ssid, password);
125
126    xpos = display.getCursorX();
127
128    // Wait until connected to WiFi
129    while (WiFi.status() != WL_CONNECTED) {
130        display.setCursor(xpos, display.getCursorY());
131        display.print(".");
132        display.display();
133        xpos = display.getCursorX();
134        if (xpos >= display.width() - 7) {
135            int16_t x1, y1;
136            uint16_t w, h;
137            display.getTextBounds(".", 0, 0, &x1, &y1, &w, &h);
138            display.setCursor(0, display.getCursorY() + h);
139            xpos = 0;
140        }
141        delay(1000);
142    }
143
144    Serial.println("Connected to WiFi network\nRequesting HTTP data");
145    display.clearDisplay();
146    display.setCursor(0, 0);
147    display.setTextSize(1);
148    display.println("Connected!");
149    display.println("Requesting HTTP data...");
150    display.display();
151}
152
153// Function to perform HTTP GET request
154bool httpGETRequest() {
155    connectToWiFi();
156    display.setTextSize(1);
157    if (http.begin(url)) {
158        httpCode = http.GET();
159
160        if (httpCode > 0) {
161            payload = http.getString();
162            Serial.println(payload);
163            http.end();
164
165            // Vérifiez si le payload contient une erreur du site
166            if (isSiteError(payload)) {
167                display.clearDisplay();
168                display.setCursor(0, 0);
169                display.println("Error fetching data!");
170                display.display();
171                Serial.println("Error fetching data: Invalid API key or other issue.");
172                delay(1000);
173                http.end();
174                return false;
175            }
176
177            // Traitement du payload comme précédemment
178            json = payload;
179
180            for (int i = 0; i < 10; i++) {
181                pos = json.indexOf('\n');
182                if (pos != -1) {
183                    json.remove(0, pos + 1);
184                }
185            }
186
187            lastNewline = json.lastIndexOf('\n');
188            if (lastNewline != -1) {
189                secondLastNewline = json.lastIndexOf('\n', lastNewline - 1);
190                if (secondLastNewline != -1) {
191                    json.remove(secondLastNewline);
192                }
193            }
194
195            String lines[numberoflines];
196            for (int i = 0; i < json.length(); i++) {
197                if (json[i] == '\n') {
198                    lines[lineCount] = json.substring(startIndex, i);
199                    lines[lineCount].trim();
200                    lineCount++;
201                    startIndex = i + 1;
202                }
203            }
204
205            payload = lines[0];
206            for (int i = 1; i < lineCount; i++) {
207                payload += "\n\n" + lines[i];
208            }
209            WiFi.disconnect(true);
210            return true;
211        } else {
212            // Handle HTTP request error
213            Serial.println("Error during HTTP request");
214            display.clearDisplay();
215            display.setCursor(0, 0);
216            display.println("HTTP request failed!");
217            display.display();
218            delay(1000);
219            http.end();
220            return false;
221        }
222    } else {
223        // Handle server connection error
224        Serial.println("Error connecting to server");
225        display.clearDisplay();
226        display.setCursor(0, 0);
227        display.println("Connection to the server failed!");
228        display.display();
229        delay(1000);
230        return false;
231    }
232}
233
234// Function to check if the payload contains a site-specific error
235bool isSiteError(const String& payload) {
236    return payload.indexOf("\"result\":\"error\"") != -1;
237}

#include <WiFi.h>
#include <HTTPClient.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Wire.h>

// OLED display configuration
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET     -1
#define SCREEN_ADDRESS 0x3C

// WiFi credentials
#define WIFI_SSID "YOUR-SSID"
#define WIFI_PASS "YOUR-PASSWORD"

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// API URL for exchange rates
String url = "YOUR-URL";
String json;
String payload;
const char* ssid = WIFI_SSID;
const char* password = WIFI_PASS;

// Buttons and timing configuration
const int button1 = 2;
const int button2 = 3;
const long interval = 86400000;  // 24 hours
const unsigned long screenOffTimeout = 5 * 60 * 1000;  // 5 minutes
unsigned long lastButtonPressMillis = 0;
unsigned long previousMillis = 0;
unsigned long currentMillis;
int httpCode;
int xpos;
int y = 10;
int speed = 4;
int highscrolllimit = 2;
int downscrolllimit = SCREEN_HEIGHT - 2572;
int pos;
int lastNewline;
int secondLastNewline;
int lineCount = 0;
int startIndex = 0;
int numberoflines = 163;
bool btn1State;
bool btn2State;

HTTPClient http;

void setup() {
    Serial.begin(115200);
    pinMode(button1, INPUT_PULLUP);
    pinMode(button2, INPUT_PULLUP);
    if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
        Serial.println(F("SSD1306 allocation failed"));
        for (;;);
    }
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.display();
}

void loop() {
    display.setTextSize(1);
    btn1State = digitalRead(button1);
    btn2State = digitalRead(button2);
    currentMillis = millis();

    // Update the last button press time if any button is pressed
    if (btn1State == LOW || btn2State == LOW) {
        lastButtonPressMillis = currentMillis;
    }

    // Turn off the display if the screen off timeout is reached
    if (currentMillis - lastButtonPressMillis >= screenOffTimeout) {
        display.ssd1306_command(SSD1306_DISPLAYOFF);
    } else {
        display.ssd1306_command(SSD1306_DISPLAYON);

        // Scroll up if button1 is pressed and not at the limit
        if (btn1State == LOW && y < highscrolllimit) {
            y += speed;
        }

        // Scroll down if button2 is pressed and not at the limit
        if (btn2State == LOW && y > downscrolllimit) {
            y -= speed;
        }

        // Perform an HTTP request at the specified interval or on the first run
        if (currentMillis - previousMillis >= interval || previousMillis == 0) {
            if (httpGETRequest()) {
                previousMillis = currentMillis;
            } else {
                // Display "Retrying..." for HTTP or connection errors
                Serial.println("Retrying...");
                display.clearDisplay();
                display.setCursor(0, 0);
                display.println("Retrying...");
                display.display();
                delay(1000);
            }
        }

        // Display the payload only if httpGETRequest() was successful and no site error occurred
        if (httpCode > 0 && !isSiteError(payload)) {
            display.clearDisplay();
            display.setCursor(0, y);
            display.println(payload);
            display.display();
        }
    }
}

// Function to connect to WiFi
void connectToWiFi() {
    Serial.print("Connecting to WiFi network...");
    display.clearDisplay();
    display.setCursor(0, 0);
    display.print("Connecting to WiFi...");
    display.display();

    WiFi.begin(ssid, password);

    xpos = display.getCursorX();

    // Wait until connected to WiFi
    while (WiFi.status() != WL_CONNECTED) {
        display.setCursor(xpos, display.getCursorY());
        display.print(".");
        display.display();
        xpos = display.getCursorX();
        if (xpos >= display.width() - 7) {
            int16_t x1, y1;
            uint16_t w, h;
            display.getTextBounds(".", 0, 0, &x1, &y1, &w, &h);
            display.setCursor(0, display.getCursorY() + h);
            xpos = 0;
        }
        delay(1000);
    }

    Serial.println("Connected to WiFi network\nRequesting HTTP data");
    display.clearDisplay();
    display.setCursor(0, 0);
    display.setTextSize(1);
    display.println("Connected!");
    display.println("Requesting HTTP data...");
    display.display();
}

// Function to perform HTTP GET request
bool httpGETRequest() {
    connectToWiFi();
    display.setTextSize(1);
    if (http.begin(url)) {
        httpCode = http.GET();

        if (httpCode > 0) {
            payload = http.getString();
            Serial.println(payload);
            http.end();

            // Vérifiez si le payload contient une erreur du site
            if (isSiteError(payload)) {
                display.clearDisplay();
                display.setCursor(0, 0);
                display.println("Error fetching data!");
                display.display();
                Serial.println("Error fetching data: Invalid API key or other issue.");
                delay(1000);
                http.end();
                return false;
            }

            // Traitement du payload comme précédemment
            json = payload;

            for (int i = 0; i < 10; i++) {
                pos = json.indexOf('\n');
                if (pos != -1) {
                    json.remove(0, pos + 1);
                }
            }

            lastNewline = json.lastIndexOf('\n');
            if (lastNewline != -1) {
                secondLastNewline = json.lastIndexOf('\n', lastNewline - 1);
                if (secondLastNewline != -1) {
                    json.remove(secondLastNewline);
                }
            }

            String lines[numberoflines];
            for (int i = 0; i < json.length(); i++) {
                if (json[i] == '\n') {
                    lines[lineCount] = json.substring(startIndex, i);
                    lines[lineCount].trim();
                    lineCount++;
                    startIndex = i + 1;
                }
            }

            payload = lines[0];
            for (int i = 1; i < lineCount; i++) {
                payload += "\n\n" + lines[i];
            }
            WiFi.disconnect(true);
            return true;
        } else {
            // Handle HTTP request error
            Serial.println("Error during HTTP request");
            display.clearDisplay();
            display.setCursor(0, 0);
            display.println("HTTP request failed!");
            display.display();
            delay(1000);
            http.end();
            return false;
        }
    } else {
        // Handle server connection error
        Serial.println("Error connecting to server");
        display.clearDisplay();
        display.setCursor(0, 0);
        display.println("Connection to the server failed!");
        display.display();
        delay(1000);
        return false;
    }
}

// Function to check if the payload contains a site-specific error
bool isSiteError(const String& payload) {
    return payload.indexOf("\"result\":\"error\"") != -1;
}

Downloadable files

Kicad files

Illustrative only, not a complete schematic.

exchangerate.zip

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