Good morning , i’m trying to use the particle web ide with the sample proposed when i search library for the ds18b20 sensor but on the console i get every time an event dstemp = nan
the sample provided use D2 on the photon , i connect the data terminal of the sensor to the pin 4 on the shieldshield that is equal to D6 on the photon.
i connect a 12v power supply to the shieldshield and verified the code for a D2 instead of a D6 but i’m not able to solve the problem.
ds18b20 was connected electrically following sample taken from internet for arduino uno.
please let me know.
Could you show us a picture of your setup (clearly showing the wiring), and the exact code used?
Good morning , here is the code:
#include <DS18B20.h>
DS18B20 ds18b20(D6); //Sets Pin D6 for Water Temp Sensor
int led = D7;
char szInfo[64];
float pubTemp;
double celsius;
double fahrenheit;
unsigned int Metric_Publish_Rate = 30000;
unsigned int MetricnextPublishTime;
int DS18B20nextSampleTime;
int DS18B20_SAMPLE_INTERVAL = 2500;
int dsAttempts = 0;
void setup() {
Time.zone(-5);
Particle.syncTime();
pinMode(D6, INPUT);
Particle.variable("tempHotWater", &fahrenheit, DOUBLE);
Serial.begin(115200);
}
void loop() {
if (millis() > DS18B20nextSampleTime){
getTemp();
}
if (millis() > MetricnextPublishTime){
Serial.println("Publishing now.");
publishData();
}
}
void publishData(){
if(!ds18b20.crcCheck()){ //make sure the value is correct
return;
}
sprintf(szInfo, "%2.2f", fahrenheit);
Particle.publish("dsTmp", szInfo, PRIVATE);
MetricnextPublishTime = millis() + Metric_Publish_Rate;
}
void getTemp(){
if(!ds18b20.search()){
ds18b20.resetsearch();
celsius = ds18b20.getTemperature();
Serial.println(celsius);
while (!ds18b20.crcCheck() && dsAttempts < 4){
Serial.println("Caught bad value.");
dsAttempts++;
Serial.print("Attempts to Read: ");
Serial.println(dsAttempts);
if (dsAttempts == 3){
delay(1000);
}
ds18b20.resetsearch();
celsius = ds18b20.getTemperature();
continue;
}
dsAttempts = 0;
fahrenheit = ds18b20.convertToFahrenheit(celsius);
DS18B20nextSampleTime = millis() + DS18B20_SAMPLE_INTERVAL;
Serial.println(fahrenheit);
}
}
I don't think setting pinMode() for your OneWire pin is required (or even a good idea). Let the library do its job and don't mess with the pin you promised to the lib to have control over.
This is old syntax
it should now be
Particle.variable("tempHotWater", fahrenheit);
You may also want to try the reworked sample of the most recent library version and extend that
2 Likes
I have tried also that sample placing D6 instead of D2 but I still get nan in the event published
here the third photo
Good morning , i have tried also connecting directly to the photon on a breadboard taking voltage from 3v3 but again i get a nan reply from topic…please let me know because i need to understand if particle is ready for prime time
That connection (taping the cables together) is likely to be an issue. Try tinning the wires, and inserting them directly.
Connecting it without the Shield shield, should work as well.
Have you implemented the improvements @ScruffR mentioned?
2 Likes
just to let you know , with the same hardware setup but with ds18x20-temperature.ino sample i was able to get the temperature from the ds18b20 sensor so i think there is something in the DS18B20.h that is wrong, here the code from the sample mentioned that works:
/*
Use this sketch to read the temperature from 1-Wire devices
you have attached to your Particle device (core, p0, p1, photon, electron)
Temperature is read from: DS18S20, DS18B20, DS1822, DS2438
I/O setup:
These made it easy to just ‘plug in’ my 18B20
D3 - 1-wire ground, or just use regular pin and comment out below.
D4 - 1-wire signal, 2K-10K resistor to D5 (3v3)
D5 - 1-wire power, ditto ground comment.
A pull-up resistor is required on the signal line. The spec calls for a 4.7K.
I have used 1K-10K depending on the bus configuration and what I had out on the
bench. If you are powering the device, they all work. If you are using parasitic
power it gets more picky about the value.
#include "DS18.h"
DS18 sensor(D0);
void setup() {
Serial.begin(9600);
// Set up 'power' pins, comment out if not used!
pinMode(D3, OUTPUT);
pinMode(D5, OUTPUT);
digitalWrite(D3, LOW);
digitalWrite(D5, HIGH);
}
void loop() {
// Read the next available 1-Wire temperature sensor
if (sensor.read()) {
// Do something cool with the temperature
Serial.printf("Temperature %.2f C %.2f F ", sensor.celsius(), sensor.fahrenheit());
Particle.publish("temperature", String(sensor.celsius()), PRIVATE);
// Additional info useful while debugging
printDebugInfo();
// If sensor.read() didn't return true you can try again later
// This next block helps debug what's wrong.
// It's not needed for the sensor to work properly
} else {
// Once all sensors have been read you'll get searchDone() == true
// Next time read() is called the first sensor is read again
if (sensor.searchDone()) {
Serial.println("No more addresses.");
// Avoid excessive printing when no sensors are connected
delay(250);
// Something went wrong
} else {
printDebugInfo();
}
}
Serial.println();
}
void printDebugInfo() {
// If there's an electrical error on the 1-Wire bus you'll get a CRC error
// Just ignore the temperature measurement and try again
if (sensor.crcError()) {
Serial.print("CRC Error ");
}
// Print the sensor type
const char *type;
switch(sensor.type()) {
case WIRE_DS1820: type = "DS1820"; break;
case WIRE_DS18B20: type = "DS18B20"; break;
case WIRE_DS1822: type = "DS1822"; break;
case WIRE_DS2438: type = "DS2438"; break;
default: type = "UNKNOWN"; break;
}
Serial.print(type);
// Print the ROM (sensor type and unique ID)
uint8_t addr[8];
sensor.addr(addr);
Serial.printf(
" ROM=%02X%02X%02X%02X%02X%02X%02X%02X",
addr[0], addr[1], addr[2], addr[3], addr[4], addr[5], addr[6], addr[7]
);
// Print the raw sensor data
uint8_t data[9];
sensor.data(data);
Serial.printf(
" data=%02X%02X%02X%02X%02X%02X%02X%02X%02X",
data[0], data[1], data[2], data[3], data[4], data[5], data[6], data[7], data[8]
);
}