Nominal value of thermistor


#1

I have attached an arduino nano and add a thermistor device with a branch of resistors( 47k and 18k) . It gives an erroneous and fixed value because it is connected to a branch of resistors. What nominal value must have the thermistor and what should be the value of the other resistor. This is not specified !!!
Thank you


#2

Oops, sorry had the wrong tab open :slight_smile:


#3

HI @manrobles,

You are having trouble adding a thermistor right? What is the issue you are having with adding the thermistor to your dashboard? Would be helpful to share code and also wiring.

-B


#4

Hi.
Thanks for answering.
I had not entered the code to arduino, that’s why the sensor did not work !!!
Already did . At this moment I have a fixed 4,7K branch (thermistor) and 12k to earth. I have 34 degrees celcuis. The temperature does not change since 4k7 is fixed. Somewhere in the code, you should be able to set the nominal value of the thermistor. BUT I DO NOT FIND IT !!!.
I enclose a copy of my code !!
Also the arduino with ENC28JC is hung very often. This module is fed with 3.5 v of independent source since it consumes a lot of current. But just as it falls !!!
You know why ???
Thanks for your answer !!!

Sincerely
Pedro

#define CAYENNE_PRINT Serial
#include <UIPEthernet.h>
#include <BlynkSimpleUIPEthernet.h>
#include <CayenneDefines.h>
#include <CayenneEthernetClient.h>
char token[] = “************”;
#include <CayenneTemperature.h>
#define VIRTUAL_PIN V1
const int thermistorPin = 3;
const float resistance = 12000;
Thermistor thermistor(thermistorPin, resistance);
void setup()
{
Serial.begin(9600);
Cayenne.begin(token);
}
void loop()
{
Cayenne.run();
}
CAYENNE_OUT(VIRTUAL_PIN)
{
Cayenne.celsiusWrite(VIRTUAL_PIN, thermistor.getCelsius());
}


#5

Hello
Good night
I need to measure temperarura with arduino and I have created a widget.
Looking at the book Cayenne temperature I see that the Steinhart-Hart formula is used.
But it seems to me that the values ​​of the constants A, B, C are a particular thermistor. Please, I need to know which specific thermistor model is used for the library.
Thank you


#6

Hi @manrobles,

You should be able to set the resistance in the code. Are you using the sketch file that we have provided for thermistors?

You can look at it here: https://github.com/myDevicesIoT/CayenneArduinoSamples/blob/master/Sensors/Thermistor/Thermistor.ino

See image below as well.

I hope this helps!

-B


#7

@manrobles,

I did some investigation in another thread…

Cheers,

Craig