A classic data logger would use a MCU and its GPIO pins, a SD card, a RTC, an LCD status display and many lines of code. Today, I'll show you that you can have all in one, using a Nextion Intelligent series HMI and thus reduces cost and development time: First, the Intelligent series has everything "on board", the MCU, the GPIO pins, the RTC, the screen, and the SD card. Second, a very powerful component, the Data Record is available for these HMI displays in the Nextion Editor, which saves us, let's say around 500 lines of C code. But telling you this is one thing, giving you a demo project at hands which covers all functionalities and which you can modify and extend as you need for your project is today's topic. 

First of all, a happy new 2023! I'll use this occasion to introduce a new type of Sunday blog post: From now on, every now and then, I'll publish a collection of FAQ around a specific topic, to compile support requests, forum posts, and questions asked in social media or by email...

Whatever you are currently celebrating, Christmas, Hanukkah, Jul, Samhain, Festivus, or any other end-of-the-civil-year festivities, I wish you a good time! This December 25th edition of the Nextion Sunday Blog won't be loaded with complex mathematical theory or hyper-efficient but difficult to understand code snippets. It's about news and information. Please read below...

After two theory-loaded blog posts about handling data array-like in strings (Strings, arrays, and the less known sp(lit)str(ing) function and Strings & arrays - continued) which you are highly recommended to read before continuing here, if you haven't already, it's big time to see how things work in practice! We'll use a string variable as a lookup lookup table containing data of one single wave period and add this repeatedly to a waveform component until it's full.

A few weeks ago, I wrote this article about using a text variable as an array, either an array of strings or an array of numbers, using the covx conversion function in addition for the latter, to extract single elements with the help of the spstr function. It's a convenient and almost a "one fits all" solution for most use cases and many of the demo projects or the sample code attached to the Nextion Sunday Blog articles made use of it, sometimes even without mentioning it explicitly since it's almost self-explaining. Then, I got a message from a reader, writing: "... Why then didn't you use it for the combined sine / cosine lookup table in the flicker free turbo gauge project?"

105 editions of the Nextion Sunday blog in a little over two years - time to look back and forth at the same time. Was all the stuff I wrote about interesting for my readers? Is it possible at all to satisfy everybody - hobbyists, makers, and professionals - at the same time? Are people (re-)using the many many HMI demo projects and code snippets? Is anybody interested in the explanation of all the underlying basics like the algorithms for calculating square roots and trigonometric functions with Nextion's purely integer based language? Are optimized code snippets which allow to save a few milliseconds here and there helpful to other developers?