数回JSON関連の実験をしたが、いざTinyWebDBのAPIの実験を始まると、また引っかかるところが多い。

色々と検索してところ、ThingspeakのAPIサンプルが見つかったので、ちょっと曲がり道して試すことに。

センサーの温度と気圧をThingspeakにアップして、動きを見て見る。

まずThingspeakのアカウントを申請して、THINGSPEAK_API_KEYを取得する。

https://thingspeak.com/users/sign_up

次はサンプルを見ながら、プログラミング。

#include <Adafruit_BMP280.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
 
#define OLED_RESET 0  // GPIO0
Adafruit_SSD1306 OLED(OLED_RESET);

#define BMP_SCK 13
#define BMP_MISO 12
#define BMP_MOSI 11 
#define BMP_CS 10

Adafruit_BMP280 bmp; // I2C
//Adafruit_BMP280 bmp(BMP_CS); // hardware SPI
//Adafruit_BMP280 bmp(BMP_CS, BMP_MOSI, BMP_MISO,  BMP_SCK);


#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>

/***************************
 * Begin Settings
 **************************/

const char* host = "http://api.thingspeak.com";
const char* THINGSPEAK_API_KEY = "＊＊＊＊＊＊＊＊＊＊＊";

// Update every 600 seconds = 10 minutes. Min with Thingspeak is ~20 seconds
const int UPDATE_INTERVAL_SECONDS = 600;

//needed for library
#include <DNSServer.h>
#include "WiFiManager.h"          //https://github.com/tzapu/WiFiManager

void configModeCallback (WiFiManager *myWiFiManager) {
  Serial.println("Entered config mode");
  Serial.println(WiFi.softAPIP());
  //if you used auto generated SSID, print it
  Serial.println(myWiFiManager->getConfigPortalSSID());
}

/***************************
 * End Settings
 **************************/
 
void setup() {
  OLED.begin();
  OLED.clearDisplay();
 
  //Add stuff into the 'display buffer'
  OLED.setTextWrap(false);
  OLED.setTextSize(1);
  OLED.setTextColor(WHITE);
  OLED.setCursor(0,0);
  delay(10);
  
  Serial.begin(115200);
  delay(10);

  // We start by connecting to a WiFi network

  // Connect to WiFi network
  OLED.println("wifiManager autoConnect...");
  OLED.display(); //output 'display buffer' to screen  
 
  //WiFiManager
  //Local intialization. Once its business is done, there is no need to keep it around
  WiFiManager wifiManager;
  //reset settings - for testing
  //wifiManager.resetSettings();

  //set callback that gets called when connecting to previous WiFi fails, and enters Access Point mode
  wifiManager.setAPCallback(configModeCallback);

  //fetches ssid and pass and tries to connect
  //if it does not connect it starts an access point with the specified name
  //here  "AutoConnectAP"
  //and goes into a blocking loop awaiting configuration
  if(!wifiManager.autoConnect()) {
    Serial.println("failed to connect and hit timeout");
    //reset and try again, or maybe put it to deep sleep
    ESP.reset();
    delay(1000);
  } 

  // Print the IP address
  OLED.print("http://");
  OLED.print(WiFi.localIP());
  OLED.println("/");
  OLED.println("WiFi connected");
  OLED.display(); //output 'display buffer' to screen  
  
  //if you get here you have connected to the WiFi
  Serial.println("connected...yeey :)");

  if (!bmp.begin(0x76)) 
  {
    OLED.println("Could not find BMP180 or BMP085 sensor at 0x77");
    OLED.display(); //output 'display buffer' to screen  
    while (1) {}
  }

}

void loop() {      
  // read values from the sensor
  float pressure = bmp.readPressure();
  float temperature = bmp.readTemperature();
  
  // We now create a URI for the request
  String url = host;
  url += "/update?api_key=";
  url += THINGSPEAK_API_KEY;
  url += "&field1=";
  url += String(temperature);
  url += "&field2=";
  url += String(pressure);
  
  Serial.print("Requesting URL: ");
  Serial.println(url);

  HTTPClient http;
  Serial.print("[HTTP] begin...\n");
  // configure targed server and url
  http.begin(url);
  
  Serial.print("[HTTP] GET...\n");
  // start connection and send HTTP header
  int httpCode = http.GET();

  if(httpCode == HTTP_CODE_OK) {
    String buffer = http.getString();
    Serial.println(buffer);
  }

  Serial.println("closing connection");

  // Go back to sleep. If your sensor is battery powered you might
  // want to use deep sleep here
  delay(1000 * UPDATE_INTERVAL_SECONDS);
}

こちら問題なくデータの蓄積ができた。