DS18B20 and Particle Photon #

Wiring #

Components #

• DS18B20 -- Dallas Semiconductor's temperature sensor that uses the Onewire protocol
  • Using it in non-parasitic mode
  • Case style
• 4.7k resistor
• Particle Photon

Details #

Phase 1 #

• Operate with 3.3v for the circuit side of things.
  • connected to gnd and 3v3 from the board power
  • DATA pin connected to D2 on particle photon
• Initial code
  • pulled out a copy of the blink code
  • using the blinking LED as a baseline to ensure the board is working
  • reads the temperature sensor and if successful, publishes the celcius temperature to the particle cloud.
  • Loop has about 4 seconds of delay in it.
• NOTICED that the sensor would not read on every cycle.

 1#include "DS18.h"
 2
 3
 4DS18 sensor(D2);
 5
 6int led2 = D7; // Instead of writing D7 over and over again, we'll write led2
 7double tempC = 0; // temperature in celcius from the ds18b20
 8
 9
10void setup() {
11  pinMode(led2, OUTPUT);
12  Particle.variable("tempC", tempC); // makes a r/w var queryable through UI
13}
14
15void loop() {
16  digitalWrite(led2, HIGH);
17
18  delay(2000);
19
20  digitalWrite(led2, LOW);
21
22  if (sensor.read()) {
23    tempC = sensor.celsius();
24    Particle.publish("temperature", String(tempC), PRIVATE);
25  } 
26  delay(2000);
27}
28

Phase 2 #

Working on ideas for storing some of the data

• Particle web console looks like for the free account has 100k data request limits.
  • I burned through a bunch leaving the particle publishing temperature overnight not realizing the limitation
  • Dialed it back down to about every 5 minutes and that should keep quota alright.
• Connected to an MQTT broker to publish more often to see what is going on.
  • brew install mosquitto to get a client that I can monitor what is getting published more frequently from the device. Note: a particle photon is a WiFi device.
  • mosquitto_sub -t invermere/temperature -h mqtt.eclipseprojects.io <-- open to anyone wanting to take a boring look at temperature values coming in.
    • There are some conflicting addresses for the location of the 'free-to-use' mqtt broker. This one above works well enough for testing.
    • I am looking to understand what it would take to set up a build pack for heroku to have an mqtt broker running as well as a client.
  • Considering how to feed this into the stathat on top of the webhook integration I did after the particle value is published.

July 25, 2022 #

• On the weekend did some work to see if I could get the thing installed. Ran into a bunch of goofy problems.
  1. Seems that when mounted in the case that I made for it the temperature was reading way wrong.
     - Maybe soemthing to do with the bendy lines, no idea. Taking it out of that box and dangling it, seemed to fix the issues - [ ] Need new box for the sensor at least
  2. Power at the light location was sketch. The timer circuit in the house is just pulsing the power to those end points. 1. Need to re-wire the switch to remove the timer aspect
  3. also working with mqtt resrouces on the server side seem to be harder than it should
     1. Issues with getting them out to graphing tools.
        1. like mqtt to webhook or http call functionality
        2. or just keeping subscribed long enough cloud amqp
     2. pipdream converted a bunch then ran out of capacity

Todo #

• Remove the wiring from 5v system on photon and move to the 3.3v
• Move the GND to the other side of the chip
• Replace the Data wire from photon to the temp sensor
• Get a pure DS18B20 instead of the the DS18B20-PAR