Sending ESP Temperature to Losant using Mongoose OS

This app lets you configure your device to publish its temperature readings to Losant via MQTT periodically. The above picture shows the graph of my ESP32 temperature readings recorded via this app.

Tested Hardware

• ESP32
• ESP8266

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Installation & Flashing

For installing this app, it is necessary that you already have the mos tool installed on your machine. If not, then do so by following the instructions given here: mos Installation Guide

1. Cloning the esp-temp app

git clone https://github.com/UtkarshVerma/esp-temp

2. Building the firmware

Open the cloned repository directory in your CLI and run the following command.

mos build --arch <your device> 

The device may either be esp32 or esp8266. For example:

mos build --arch esp32

3. Flashing the device

Now flash your device using the below stated command.

mos flash 

4. Configuring WiFi

Configure WiFi on your device using the following command. Ignore '<' and '>'.

mos wifi "<your WiFi SSID>" "<your WiFi password>"

For example:

mos wifi "Home WiFi" "home@123"

5. Setting up Losant

To use this app, you are required to have a device as well as an application set up on Losant. To do so, you may refer to these Losant documentations:

Creating A Device

Generating Access Keys

While creating the device, be sure to add a device attribute with the following properties:

• Name: temp
• Data Type: Number

6. Configuring the MQTT connection to Losant

Set up the MQTT credentials on your Mongoose OS flashed device using the following command.

mos config-set mqtt.client_id=<your Losant device id> \
  mqtt.user=<your Losant access key > \
  mqtt.pass=<your Losant access secret>

The Device ID can be obtained on Losant. The Access Key and Access Secret can be obtained on Losant. If you don't already have one at your disposal, you may generate one by following the official instructions stated in the Losant Docs.

Once these are set up, your device should now be sending data to Losant.

7. Additional Losant Set-up

Once you've done all the above steps, you may use the temperature readings for doing anything by accessing the temp attribute values. I used them to plot a graph.

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Some App Features

This app comes with some integrated features for usage convenience. They are as stated below:

otaMode

Since this app, that is esp-temp, has deep sleep enabled, therefore passing commands via the console isn't possible as deep sleep is enabled within few seconds of booting. So, to make this app support over the air updates as well as quick code editing via the UI, an OTA Mode has been implemented which disables deep sleep mode for one boot cycle. To enable OTA Mode, the Flash or Boot button on the development board has to be pressed right after the device has booted up.

The best way to check if the device has booted or not is by seeing the device logs via the mos console command.

As a response, a message will be displayed in the logs saying OTA Mode on! and the device LED will start to glow on successful enabling of the OTA mode.

enableConv

This app has the facility to send temperature to Losant in either Celsius or Fahrenheit. By default, the temperature will be sent in Celsius but it may be changed to Fahrenheit by setting the enableConv value as false in the app code.

tempOffset

Since this app relies on the internal temperature sensor of ESP32/8266, which reads the temperature of the MCU, therefore the temperature readings are bound to be off by a certain value from the ambient temperature. To make the readings approximately equal to the ambient temperature, we may subtract a specific value from the readings. That additional value is the tempOffset.

The graph of MCU temperature and ambient temperature versus time are almost alike if not for the upward shifting due to the additional MCU internal heat. The tempOffset value compensates for it and that is the core concept of this app for obtaining approximate temperature readings.

This app subtracts tempOffset value from the temperature readings so a positive value represents decrement and vice versa.

It is set to 17 by default.

minToSleep

It is up to you to set the interval between to consistent temperature readings, or in other words, the period. minToSleep variable contains the value which decides the sleep time of the device, that is the amount of time(in minutes) after which it has to wake and send another temperature reading to Losant.

It is set to 20 by default, meaning that a temperature reading will be sent to Losant every 20 minutes.