esp8266

In this example we will display the price in USD of 1 bitcoin, the data is taken from coindesk's API and displayed on an oled display.

This is similar to our previous examples, you do not need to use a Wemos mini or the OLED shield below but this makes the project easier to build

Here is the oled shield for the Wemos mini

Here is the wemos mini

Code

[c]

#include <ESP8266WiFi.h>
#include <Wire.h>
#include <SFE_MicroOLED.h>
#include <ArduinoJson.h>

const char* ssid = “iainhendry”;
const char* pass = “iain061271”;
#define PIN_RESET 255 //
#define DC_JUMPER 0 // I2C Addres: 0 – 0x3C, 1 – 0x3D
String id;
String value;
String json;

MicroOLED oled(PIN_RESET, DC_JUMPER); // I2C Example

WiFiClient client;

// delay between updates
const unsigned long postingInterval = 60L * 1000L;
unsigned long lastConnectionTime = 0;

void setup()
{
delay(100);
Serial.begin(115200);
Serial.println();
Serial.println();
Serial.print(“Connecting to “);
Serial.println(ssid);
WiFi.begin(ssid, pass);
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(“.”);
}
Serial.println(“”);
Serial.println(“WiFi connected”);
Serial.println(“IP address: “);
Serial.println(WiFi.localIP());

Serial.print(“Connecting to “);

oled.begin();
oled.clear(ALL);
oled.setCursor(0,0);
oled.display();
oled.clear(PAGE);
oled.clear(ALL);
oled.print(“Bitcoin price”);
oled.setCursor(0,1);
oled.print(“loading..”);
oled.display(); // Display what's in the buffer (splashscreen)
delay(50);

}

int check_connect = 0;

void httpRequest()
{
client.stop();

// if there's a successful connection:
if (client.connect(“api.coindesk.com”, 80))
{
Serial.println(“connecting…”);
client.println(“GET /v1/bpi/currentprice.json HTTP/1.1”);
client.println(“Host: api.coindesk.com”);
client.println(“User-Agent: ESP8266/1.1”);
client.println(“Connection: close”);
client.println();
lastConnectionTime = millis();
}
else
{
// if you couldn't make a connection:
Serial.println(“connection failed”);
}
}

void loop()
{
int cnt;

if (cnt++ == 10000)
{
cnt = 0;
if (check_connect++ == 50)
{
check_connect = 0;
if (WiFi.status() != WL_CONNECTED)
{
}
}
}

if (millis() – lastConnectionTime > postingInterval)
{
httpRequest();
unsigned int i = 0; //timeout counter
int n = 1; // char counter
char json[500] =”{“;

while (!client.find(“\”USD\”:{“)){}

while (i<20000)
{
if (client.available())
{
char c = client.read();
json[n]=c;
if (c=='}') break;
n++;
i=0;
}
i++;
}

StaticJsonBuffer<500> jsonBuffer;
JsonObject& root = jsonBuffer.parseObject(json);

String newjson = root[“code”];
String value = root[“rate”];
id = newjson.substring(9,12);

// value = newjson.substring(41,51);
oled.display();
oled.clear(PAGE); // Clear the display's internal memory
oled.clear(ALL); // Clear the library's display buffer
oled.setCursor(0,1);
oled.print(value);
oled.display();

id=””;
value=””;
}
}

[/c]

testing

You should see something like this on the oled display

esp8266 bitcoin ticker

Links

Here are some of the products I used

Smart Electronics D1 mini – Mini NodeMcu 4M bytes Lua WIFI Internet of Things development board based ESP8266 by WeMos

0.66″ inch For Wemos Oled 64X48 IIC I2C LCD OLED LED Dispaly Shield for Arduino Compatible For WeMos D1 Mini SSD1306 OLED Shield

This is similar to our previous ESP8266 bitcoin example – Basic ESP8266 and bitcoin price example

We used the same Wemos board as in the previous example

In this example we use ArduinoJson library to parse the json response from coindesk. A better approach than the previous example

Again you will have to change the username and password for your wifi credentials

const char* ssid = “your username here”;
const char* pass = “your password here”;

Again we will display the results via the serial monitor

Code

Open the library manager and add support for the ArduinoJson library to the Arduino IDE

Copy and paste the following code into the Arduino IDE, build and program your board

[c]

#include <ESP8266WiFi.h>
#include <ArduinoJson.h>

const char* ssid = “your username here”;
const char* pass = “your password here”;

String id;
String value;
String json;

WiFiClient client;

const unsigned long postingInterval = 60L * 1000L;
unsigned long lastConnectionTime = 0;

void setup()
{
delay(100);
Serial.begin(115200);
Serial.println();
Serial.println();
Serial.print(“Connecting to “);
Serial.println(ssid);
WiFi.begin(ssid, pass);
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(“.”);
}
Serial.println(“”);
Serial.println(“WiFi connected”);
Serial.println(“IP address: “);
Serial.println(WiFi.localIP());
delay(50);

}

int check_connect = 0;

void httpRequest()
{
client.stop();

// if there's a successful connection:
if (client.connect(“api.coindesk.com”, 80))
{
Serial.println(“connecting…”);
client.println(“GET /v1/bpi/currentprice.json HTTP/1.1”);
client.println(“Host: api.coindesk.com”);
client.println(“User-Agent: ESP8266/1.1”);
client.println(“Connection: close”);
client.println();
lastConnectionTime = millis();
}
else
{
// if you couldn't make a connection:
Serial.println(“connection failed”);
}
}

void loop()
{
int cnt;

if (cnt++ == 10000) {
cnt = 0;
if (check_connect++ == 50) {
check_connect = 0;
if (WiFi.status() != WL_CONNECTED) {

}
}
}

if (millis() – lastConnectionTime > postingInterval) {
httpRequest();
unsigned int i = 0; //timeout counter
int n = 1; // char counter
char json[500] =”{“;

while (!client.find(“\”USD\”:{“)){}

while (i<20000) {
if (client.available()) {
char c = client.read();
json[n]=c;
if (c=='}') break;
n++;
i=0;
}
i++;
}

Serial.println(json);

StaticJsonBuffer<500> jsonBuffer;
JsonObject& root = jsonBuffer.parseObject(json);

String newjson = root[“code”];
String value = root[“rate”];
id = newjson.substring(9,12);

Serial.print(“1 bitcoin = USD value : “);
Serial.println(value);

id=””;
value=””;
}
}

[/c]

Testing

Open the serial monitor and you should see something like this if everything goes to plan

Connecting to ****************
…………..
WiFi connected
IP address:
192.168.1.15
connecting…
{“code”:”USD”,”symbol”:”$”,”rate”:”9,692.3175″,”description”:”United States Dollar”,”rate_float”:9692.3175}
1 bitcoin = USD value : 9,692.3175