How to show the temperature and humidity of your room on a Heltec WiFi Kit 32 attached to a DHT11 / DHT22 sensor

When you have a DHT11 / DHT22 sensor, you can measure the temperature and humidity of your room. If you attach the sensor to a Heltec WiFi Kit 32 development board, you will be able to put up the readings on a 0.96 Inch OLED screen.

Given these points, let’s look at how we can show the temperature and humidity readings of your room on a Heltec WiFi Kit 32 development board attached to a DHTXX sensor.

Why get a Wio Terminal for your next IoT project?

If you have 30 USD and is looking for a microcontroller, then you will want to consider the Wio Terminal.

Since Seeed Studio had kindly sent me one for free, I got to picture my 30 bucks alongside the box:

Wio Terminal front of box with 30 USD

Although 30 bucks is not a lot of money, it is good to know what the Wio Terminal is capable of before buying. When we do so, we can prevent adding on to that electronics stockpile which is collecting dust in the house.

Given these points., let’s look at why you will want get a Wio Terminal for your next IoT project.

How to prevent “Uncaught ReferenceError: jQuery / $ is not defined”

When you want to build a microsite, jQuery can help you simplify client side interactivity. If you build your website with WordPress, then you will be able to use jQuery in the custom theme that you are building.

Since you will base your site interactivity on jQuery, you may write JavaScript codes that throw the following error:

Uncaught ReferenceError: jQuery / $ is not defined.

In some cases, the error may appear randomly, making it hard to detect.

So how can we prevent our JavaScript codes from throwing a “Uncaught ReferenceError: jQuery / $ is not defined”?

How to use pycrypto, python-qrcode and Flask-RESTPlus to create QR codes that can send encrypted data to an endpoint

If you want to direct someone to a web page without saying a word, then you can use QR codes to do so.

For example, your QR code reader will direct your phone’s browser to visit our home page when you scan the following QR Code:

Techcoil home page QRCode

Given that, you can use QR codes to send HTTP requests to an endpoint of your HTTP server. In addition, you can embed data that you wish to send to the endpoint in the QR codes.

With this in mind, let’s look at how we can use pycrypto, python-qrcode and Flask-RESTPlus to create QR codes that can send encrypted data to an endpoint.

How to use threading.Condition to wait for several Flask-APScheduler one-off jobs to complete execution in your Python 3 application

Previously, I discussed how to use Flask-APScheduler in your Python 3 Flask application to run multiple tasks in parallel, from a single HTTP request.

When we run jobs as discussed in that post, jobs are ran once by the underlying ApScheduler instance. In addition, our Flask endpoint return the HTTP response back to the HTTP client as soon as the jobs are scheduled.

If we do not want the HTTP client to know the outcome of the jobs within that HTTP call, then we are good. But what if we want to include any errors that the jobs encounter in the same HTTP response?

In such a situation, we will need a mechanism to wait for the one-off jobs to complete execution before returning that response.

Given that in mind, this post shows how we can use threading.Condition to wait for several Flask-APScheduler one-off jobs to complete execution.

How to create an interval task that runs periodically within your Python 3 Flask application with Flask-APScheduler

Previously, I talked about how to use Flask-APScheduler in your Python 3 Flask application to run multiple tasks in parallel, from a single HTTP request.

If you wish to run long running tasks triggered by an HTTP request, then that post will help you do so.

However, what if you want to run jobs periodically without blocking your Flask HTTP server from serving HTTP requests?

In this case, you will want to run an interval task with Flask-APScheduler.

Given that, let’s look at how we can use Flask-APScheduler to create an interval task within your Python 3 Flask application.