Temperature drops occasionally from 59+C to -13C or to other random values. Used sketch and info from this site: http://internetofthinking.blogspot.com/2016/02/upload-ds18b20-temperature-sensor-data.html
NodeMCU powered by phone charger 5v 1a via microUSB. Placing 4.7 kOm resistor between data wire and 3v3 didn't help me.
Does anyone know how to solve this issue? Like filtering results and pushing to server only values that do not differ by more than n*C, or something like that?
Here is the sketch
#include <ESP8266WiFi.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#define myPeriodic 15 //in sec | Thingspeak pub is 15sec
#define ONE_WIRE_BUS 2 // DS18B20 on arduino pin2 corresponds to D4 on physical board
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature DS18B20(&oneWire);
float prevTemp = 0;
const char* server = "api.thingspeak.com";
String apiKey ="-";
const char* MY_SSID = "-";
const char* MY_PWD = "-";
int sent = 0;
void setup() {
Serial.begin(115200);
connectWifi();
}
void loop() {
float temp;
//char buffer[10];
DS18B20.requestTemperatures();
temp = DS18B20.getTempCByIndex(0)+5;
//String tempC = dtostrf(temp, 4, 1, buffer);//handled in sendTemp()
Serial.print(String(sent)+" Temperature: ");
Serial.println(temp);
//if (temp != prevTemp)
//{
//sendTeperatureTS(temp);
//prevTemp = temp;
//}
sendTeperatureTS(temp);
int count = myPeriodic;
while(count--)
delay(1000);
}
void connectWifi()
{
Serial.print("Connecting to "+*MY_SSID);
WiFi.begin(MY_SSID, MY_PWD);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.print(".");
}
Serial.println("");
Serial.println("Connected");
Serial.println("");
}//end connect
void sendTeperatureTS(float temp)
{
WiFiClient client;
if (client.connect(server, 80)) { // use ip 184.106.153.149 or api.thingspeak.com
Serial.println("WiFi Client connected ");
String postStr = apiKey;
postStr += "&field1=";
postStr += String(temp);
postStr += "\r\n\r\n";
client.print("POST /update HTTP/1.1\n");
client.print("Host: api.thingspeak.com\n");
client.print("Connection: close\n");
client.print("X-THINGSPEAKAPIKEY: " + apiKey + "\n");
client.print("Content-Type: application/x-www-form-urlencoded\n");
client.print("Content-Length: ");
client.print(postStr.length());
client.print("\n\n");
client.print(postStr);
delay(1000);
}//end if
sent++;
client.stop();
}//end send
