Ardunio / ESP8266 / Hardware

ESP8266 JSON Weather Display

by linuxgeek · Published January 2, 2015 · Updated June 18, 2015

This is my first attempt to receive data with an Arduino and the ESP8266 WiFi-Module. This program is based on the example by Seedstudio, and displays weather data on a small TFT display.

The JSON

The weather updates can be requested as JSON data from

http://api.openweathermap.org/data/2.5/weather?id=2925533

This was the result got from the website

{"coord":{"lon":8.68,"lat":50.12},"sys":{"message":0.0037,"country":"DE","sunrise":1420183442,"sunset":1420212885},"weather":[{"id":501,"main":"Rain","description":"moderate rain","icon":"10d"}],"base":"cmc stations","main":{"temp":275.405,"temp_min":275.405,"temp_max":275.405,"pressure":1004.48,"sea_level":1039.53,"grnd_level":1004.48,"humidity":96},"wind":{"speed":6.69,"deg":239.001},"clouds":{"all":92},"rain":{"3h":4},"dt":1420188399,"id":2925533,"name":"Frankfurt am Main","cod":200}

{"coord":{"lon":8.68,"lat":50.12},"sys":{"message":0.0037,"country":"DE","sunrise":1420183442,"sunset":1420212885},"weather":[{"id":501,"main":"Rain","description":"moderate rain","icon":"10d"}],"base":"cmc stations","main":{"temp":275.405,"temp_min":275.405,"temp_max":275.405,"pressure":1004.48,"sea_level":1039.53,"grnd_level":1004.48,"humidity":96},"wind":{"speed":6.69,"deg":239.001},"clouds":{"all":92},"rain":{"3h":4},"dt":1420188399,"id":2925533,"name":"Frankfurt am Main","cod":200}

The Module

This Version has two LEDs, one for Power and another one which is connected to the TX-Pin. It runs at 3.3 Volt and the serial port is set to a data rate of 115200 baud. The CH_PD-Pin has to be high. After a reset, the module sends the following data:

AT+RST
OK
 
 ets Jan  8 2013,rst cause:4, boot mode:(3,6)
 
wdt reset
load 0x40100000, len 24236, room 16
tail 12
chksum 0xb7
ho 0 tail 12 room 4
load 0x3ffe8000, len 3008, room 12
tail 4
chksum 0x2c
load 0x3ffe8bc0, len 4816, room 4
tail 12
chksum 0x46
csum 0x46
 
ready

AT+RST

ets Jan 8 2013,rst cause:4, boot mode:(3,6)

wdt reset

load 0x40100000, len 24236, room 16

tail 12

chksum 0xb7

ho 0 tail 12 room 4

load 0x3ffe8000, len 3008, room 12

tail 4

chksum 0x2c

load 0x3ffe8bc0, len 4816, room 4

tail 12

chksum 0x46

csum 0x46

ready

Wiring

The wiring is quite simple. The wifi-module needs just two wires for power and two for the serial interface. As a display i used a 1.8″ (45.72 mm) TFT-display that is connected via SPI.

Arduino	ESP8266 Module	Display Module
3.3V	VCC & CH_PD
5V		VCC
GND	GND	GND & BKL
0 (RX)	TX
1 (TX)	RX
8		RESET
9		RS
10		LCD CS
11		MOSI
13		SLCK

The Program

I changed the source code from Seedstudio a little bit, because at 115200 baud the 64 Byte uart-buffer from the Arduino fills up very fast. But overall the program is really simple.

#include <SoftwareSerial.h>
#include <JsonParser.h>
 
#define cs   10  // Pins for the display
#define dc   9
#define rst  8
 
#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_ST7735.h> // Hardware-specific library
#include <SPI.h>
 
Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, rst);
 
using namespace ArduinoJson::Parser;
 
#define SSID "<ssid>" // insert your SSID
#define PASS "<password>" // insert your password
#define LOCATIONID "2925533" // location id
#define DST_IP "188.226.224.148" //api.openweathermap.org
SoftwareSerial dbgSerial(2, 3); // RX, TX for debugging
JsonParser<32> parser;
 
void setup()
{
  Serial.begin(115200);
  Serial.setTimeout(5000);
  dbgSerial.begin(9600); // for debuging
  dbgSerial.println("Init");
  tft.initR(INITR_BLACKTAB);
  tft.setRotation(1);
  tft.fillScreen(ST7735_BLACK);
  tft.setCursor(2, 2);
  tft.setTextColor(ST7735_WHITE);
  Serial.println("AT+RST"); // restet and test if module is redy
  delay(1000);
  if(Serial.find("ready")) {
    dbgSerial.println("WiFi - Module is ready");
    tft.println("WiFi - Module is ready");
  }else{
    dbgSerial.println("Module dosn't respond.");
    tft.println("Module dosn't respond.");
    tft.println("Please reset.");
    while(1);
  }
  delay(1000);
  // try to connect to wifi
  boolean connected=false;
  for(int i=0;i<5;i++){
    if(connectWiFi()){
      connected = true;
      tft.println("Connected to WiFi...");
      break;
    }
  }
  if (!connected){
    tft.println("Coudn't connect to WiFi.");
    while(1);
  }
  delay(5000);
  Serial.println("AT+CIPMUX=0"); // set to single connection mode
}
void loop()
{
  String cmd = "AT+CIPSTART="TCP","";
  cmd += DST_IP;
  cmd += "",80";
  Serial.println(cmd);
  dbgSerial.println(cmd);
  if(Serial.find("Error")) return;
  cmd = "GET /data/2.5/weather?id=";
  cmd += LOCATIONID;
  cmd += " HTTP/1.0rnHost: api.openweathermap.orgrnrn";
  Serial.print("AT+CIPSEND=");
  Serial.println(cmd.length());
  if(Serial.find(">")){
    dbgSerial.print(">");
  }else{
    Serial.println("AT+CIPCLOSE");
    dbgSerial.println("connection timeout");
    tft.fillScreen(ST7735_BLACK);
    tft.setCursor(2, 2);
    tft.setTextColor(ST7735_WHITE);
    tft.println("connection timeout");
    delay(1000);
    return;
  }
  Serial.print(cmd);
  unsigned int i = 0; //timeout counter
  int n = 1; // char counter
  char json[100]="{";
  while (!Serial.find(""main":{")){} // find the part we are interested in.
  while (i<60000) {
    if(Serial.available()) {
      char c = Serial.read();
      json[n]=c;
      if(c=='}') break;
      n++;
      i=0;
    }
    i++;
  }
  dbgSerial.println(json);
  JsonObject root = parser.parse(json);
  double temp = root["temp"];
  double pressure = root["pressure"];
  double humidity = root["humidity"];
  temp -= 273.15; // from kelvin to degree celsius
  tft.fillScreen(ST7735_BLACK);
  tft.setCursor(2, 25);
  tft.setTextColor(ST7735_BLUE);
  tft.setTextSize(2);
  tft.print("Temp: ");
  tft.print((int)temp);
  tft.print(".");
  tft.print((int)((temp-(int)temp)*10));
  tft.println(" C");
  tft.setCursor(2, 55);
  tft.setTextColor(ST7735_GREEN);
  tft.setTextSize(2);
  tft.print("Press: ");
  tft.print((int)pressure);
  tft.setCursor(2, 85);
  tft.setTextColor(ST7735_YELLOW);
  tft.setTextSize(2);
  tft.print("Humidity: ");
  tft.print((int)humidity);
  tft.println("%");
  dbgSerial.println(temp);
  dbgSerial.println(pressure);
  dbgSerial.println(humidity);
  dbgSerial.println("====");
  delay(600000);
}
 
boolean connectWiFi()
{
  Serial.println("AT+CWMODE=1");
  String cmd="AT+CWJAP="";
  cmd+=SSID;
  cmd+="","";
  cmd+=PASS;
  cmd+=""";
  dbgSerial.println(cmd);
  Serial.println(cmd);
  delay(2000);
  if(Serial.find("OK")){
    dbgSerial.println("OK, Connected to WiFi.");
    return true;
  }else{
    dbgSerial.println("Can not connect to the WiFi.");
    return false;
  }
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

#include <SoftwareSerial.h>

#include <JsonParser.h>

#define cs 10 // Pins for the display

#define dc 9

#define rst 8

#include <Adafruit_GFX.h> // Core graphics library

#include <Adafruit_ST7735.h> // Hardware-specific library

#include <SPI.h>

Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, rst);

using namespace ArduinoJson::Parser;

#define SSID "<ssid>" // insert your SSID

#define PASS "<password>" // insert your password

#define LOCATIONID "2925533" // location id

#define DST_IP "188.226.224.148" //api.openweathermap.org

SoftwareSerial dbgSerial(2, 3); // RX, TX for debugging

JsonParser<32> parser;

void setup()

{

Serial.begin(115200);

Serial.setTimeout(5000);

dbgSerial.begin(9600); // for debuging

dbgSerial.println("Init");

tft.initR(INITR_BLACKTAB);

tft.setRotation(1);

tft.fillScreen(ST7735_BLACK);

tft.setCursor(2, 2);

tft.setTextColor(ST7735_WHITE);

Serial.println("AT+RST"); // restet and test if module is redy

delay(1000);

if(Serial.find("ready")) {

dbgSerial.println("WiFi - Module is ready");

tft.println("WiFi - Module is ready");

}else{

dbgSerial.println("Module dosn't respond.");

tft.println("Module dosn't respond.");

tft.println("Please reset.");

while(1);

}

delay(1000);

// try to connect to wifi

boolean connected=false;

for(int i=0;i<5;i++){

if(connectWiFi()){

connected = true;

tft.println("Connected to WiFi...");

break;

}

if (!connected){

tft.println("Coudn't connect to WiFi.");

while(1);

}

delay(5000);

Serial.println("AT+CIPMUX=0"); // set to single connection mode

}

void loop()

{

String cmd = "AT+CIPSTART="TCP","";

cmd += DST_IP;

cmd += "",80";

Serial.println(cmd);

dbgSerial.println(cmd);

if(Serial.find("Error")) return;

cmd = "GET /data/2.5/weather?id=";

cmd += LOCATIONID;

cmd += " HTTP/1.0rnHost: api.openweathermap.orgrnrn";

Serial.print("AT+CIPSEND=");

Serial.println(cmd.length());

if(Serial.find(">")){

dbgSerial.print(">");

}else{

Serial.println("AT+CIPCLOSE");

dbgSerial.println("connection timeout");

tft.fillScreen(ST7735_BLACK);

tft.setCursor(2, 2);

tft.setTextColor(ST7735_WHITE);

tft.println("connection timeout");

delay(1000);

return;

}

Serial.print(cmd);

unsigned int i = 0; //timeout counter

int n = 1; // char counter

char json[100]="{";

while (!Serial.find(""main":{")){} // find the part we are interested in.

while (i<60000) {

if(Serial.available()) {

char c = Serial.read();

json[n]=c;

if(c=='}') break;

n++;

i=0;

}

i++;

}

dbgSerial.println(json);

JsonObject root = parser.parse(json);

double temp = root["temp"];

double pressure = root["pressure"];

double humidity = root["humidity"];

temp -= 273.15; // from kelvin to degree celsius

tft.fillScreen(ST7735_BLACK);

tft.setCursor(2, 25);

tft.setTextColor(ST7735_BLUE);

tft.setTextSize(2);

tft.print("Temp: ");

tft.print((int)temp);

tft.print(".");

tft.print((int)((temp-(int)temp)*10));

tft.println(" C");

tft.setCursor(2, 55);

tft.setTextColor(ST7735_GREEN);

tft.setTextSize(2);

tft.print("Press: ");

tft.print((int)pressure);

tft.setCursor(2, 85);

tft.setTextColor(ST7735_YELLOW);

tft.setTextSize(2);

tft.print("Humidity: ");

tft.print((int)humidity);

tft.println("%");

dbgSerial.println(temp);

dbgSerial.println(pressure);

dbgSerial.println(humidity);

dbgSerial.println("====");

delay(600000);

}

boolean connectWiFi()

{

Serial.println("AT+CWMODE=1");

String cmd="AT+CWJAP="";

cmd+=SSID;

cmd+="","";

cmd+=PASS;

cmd+=""";

dbgSerial.println(cmd);

Serial.println(cmd);

delay(2000);

if(Serial.find("OK")){

dbgSerial.println("OK, Connected to WiFi.");

return true;

}else{

dbgSerial.println("Can not connect to the WiFi.");

return false;

}

Conclusion

The program is quite simple and could be extended with more features like a weather forecast. If you have any comments about the source code leave it down below.

Update: There was a bug in the code, which was found by Jody Roth. This is now fixed.

Source Code

The source of this document can be found here

Tags: arduino esp8266 json weather display

ESP8266 JSON Weather Display

You may also like...

Products

ESP8266 JSON Weather Display

The Module

Wiring

The Program

You may also like...

DIY Avr Parallel port programmer

ESP8266 OLED Example

Arduino IR Remote identification

Products