Thermistor reading send to thingspeak example
Posted: Sat Mar 28, 2015 11:08 pmWas wanting to make a temperature monitor to upload to Thingspeak.com and came across this page at adafruit.com.
https://learn.adafruit.com/thermistor/using-a-thermistor
I took that example and added some wifi commands and converted to F for the temperature for us USA folks.
I am using an ESP-01 and a Arduino Mini Pro 3.3V
It boots up, connects to the wifi and every 30 seconds it takes 5 readings, averages them, and sends the temp to Thingspeak.com. I plugged it up in my location and it has been pumping along nicely since then.
Here is my code.
Hope someone finds this useful.
https://learn.adafruit.com/thermistor/using-a-thermistor
I took that example and added some wifi commands and converted to F for the temperature for us USA folks.
I am using an ESP-01 and a Arduino Mini Pro 3.3V
It boots up, connects to the wifi and every 30 seconds it takes 5 readings, averages them, and sends the temp to Thingspeak.com. I plugged it up in my location and it has been pumping along nicely since then.
Here is my code.
Code: Select all
#include <SoftwareSerial.h>
#define DEBUG
// which analog pin to connect
#define THERMISTORPIN A0
// resistance at 25 degrees C
#define THERMISTORNOMINAL 10000
// temp. for nominal resistance (almost always 25 C)
#define TEMPERATURENOMINAL 25
// how many samples to take and average, more takes longer
// but is more 'smooth'
#define NUMSAMPLES 5
// The beta coefficient of the thermistor (usually 3000-4000)
#define BCOEFFICIENT 3950
// the value of the 'other' resistor measured with my volt meter
#define SERIESRESISTOR 9870
//*-- Software Serial
#define _rxpin 10
#define _txpin 11
SoftwareSerial debug( _rxpin, _txpin ); // RX, TX
//*-- IoT Information
#define SSID "networkname"
#define PASS "password"
#define IP "184.106.153.149" // ThingSpeak IP Address: 184.106.153.149
//*-- Build GET Command
// GET /update?key=[THINGSPEAK_KEY]&field1=[data 1]&filed2=[data 2]...;
String GET = "GET /update?key=XXXXXXXXXXXXXXXX";
int samples[NUMSAMPLES];
void setup(void) {
Serial.begin(9600);
analogReference(DEFAULT);
Serial.println("AT+RST");
debug.println("ESP8266");
delay(1000);
if(Serial.find("ready"))
{
debug.println("ESP8266 CONNECTED\nREADY TO SEND DATA");
connectWiFi();
}
}
void loop(void) {
delay(30000);
// ESP8266 Client
String cmd = "AT+CIPSTART=\"TCP\",\"";
cmd += IP;
cmd += "\",80";
Serial.println(cmd);
debug.println(cmd);
delay(2000);
if(Serial.find("Error"))
{
debug.print( "CANNOT CONNECT\nEXITING" );
return;
}
uint8_t i;
float average;
// take N samples in a row, with a slight delay
for (i=0; i< NUMSAMPLES; i++) {
samples[i] = analogRead(THERMISTORPIN);
delay(10);
}
// average all the samples out
average = 0;
for (i=0; i< NUMSAMPLES; i++) {
average += samples[i];
}
average /= NUMSAMPLES;
//Serial.print("Average analog reading ");
//Serial.println(average);
// convert the value to resistance
average = 1023 / average - 1;
average = SERIESRESISTOR / average;
//Serial.print("Thermistor resistance ");
//Serial.println(average);
float steinhart;
steinhart = average / THERMISTORNOMINAL; // (R/Ro)
steinhart = log(steinhart); // ln(R/Ro)
steinhart /= BCOEFFICIENT; // 1/B * ln(R/Ro)
steinhart += 1.0 / (TEMPERATURENOMINAL + 273.15); // + (1/To)
steinhart = 1.0 / steinhart; // Invert
steinhart -= 273.15; // convert to C
steinhart = steinhart * 1.8 + 32; // convert to F
//Serial.print("Temperature ");
//Serial.print(steinhart * 1.8 + 32);
//Serial.println(" *F");
cmd = GET + "&field1=" + steinhart + "\r";
Serial.print("AT+CIPSEND=");
debug.print("AT+CIPSEND=");
Serial.println(cmd.length());
debug.println(cmd.length());
if(Serial.find(">"))
{
debug.print(">");
Serial.print(cmd);
debug.print(cmd);
}
else
{
Serial.println( "AT+CIPCLOSE" );
debug.println( "AT+CIPCLOSE" );
}
if( Serial.find("OK") )
{
debug.println( "DATA SENT" );
}
else
{
debug.println( "DATA NOT SENT\nEXITING" );
}
delay(1000);
}
boolean connectWiFi()
{
Serial.println("AT+CWMODE=1");
debug.println("AT+CWMODE=1");
delay(2000);
String cmd="AT+CWJAP=\"";
cmd+=SSID;
cmd+="\",\"";
cmd+=PASS;
cmd+="\"";
Serial.println(cmd);
delay(5000);
if(Serial.find("OK"))
{
debug.println("WIFI CONNECTED");
delay(1000);
Serial.println("AT+CIFSR");
while (Serial.available())
debug.write(Serial.read());
}
else
{
debug.println("ERROR CONNECTING TO WIFI");
return false;
}
delay(2000);
cmd = "AT+CIPMUX=0";
Serial.println( cmd );
debug.println( cmd );
if( Serial.find( "Error") )
{
debug.print( "CANNOT SET SINGLE CONNECTION MODE" );
return false;
}
}Hope someone finds this useful.
Tried alot and succeeded sometimes, mostly it appeared buggy.