matt's blog

Adding An OLED To My Computer

As part of my work I end up with hundreds of small TFT and OLED displays scattered around doing nothing. One of them, the PG25664CG OLED screen (16 shades of green) I figured would be about the same size and shape as a 5.25" drive bay in a PC.

And guess what? I was right! An absolutely (well, a couple of mm out) perfect match. So I decided I should build one into my computer to display stuff. No idea what stuff yet, but stuff anyway. I'll decide later when I have written the software for it all.

Splitting Up Text in C

A common question I often find is:

How can I split this incoming data into parts?

It's especially asked in conjunction with reading data through serial. So I thought I'd introduce you to two completely different approaches, each with benefits and drawbacks depending on the kind of data you are splitting.

So you have some data coming in through serial, or some similar stream, and you need to cut it up into different parts. The two methods basically consist of either:

What Exactly is a GPIO Pin?

I was hoping to make this the topic of my first ever video tutorial, but I still haven't got round to cleaning my desk of all the junk and setting up a holder for my phone to use as a camera. Plus I am suffering from a bad cold right now and sound awful. So text it is.

I'd like to help you get to know exactly what a digital IO pin of an Arduino actually is and how it works. Many questions I come across along the lines of "How does this work", or "Why do you need to do this", or similar, can be answered easily if you know exactly what goes on inside an IO pin.

Designing a Development Board

So I heard you were thinking about designing your own development board. That's nice. But do you know how?

It's one thing to go "I'd like to build my own development board", but it's quite a long step from there to "I have built my own development board and it works".

There's a number of steps you should go through before you even set pen to paper.

Why build another development board?

The Importance of Sharing Grounds

A lot of the time on the Arduino forums we get questions regarding wiring things together. One common format is:

I want to connect my 12V powered LED strip to my Arduino but I can't get it to communicate. I have checked all the connections and they seem fine. I have a 12V power supply for the LEDs and the Arduino is powered from the computer.

And 9 times out of 10 the first question we have to ask in return is:

Have you connected the grounds together?

Cheap 433MHz Transmitters

I decided the other day that it would be a good idea to spend 99p on a 433MHz transmitter and receiver pair from eBay. Not to use, but to take a look and see just how bad these modules are (and I expected them to be pretty awful too).

Flexible LED Fading

I'd like to introduce you to a method of fading RGB LEDs both smoothly and flexibly.

A common method of fading colours on the Arduino is to use simple for loops, such as:

Why You Can't Use Resistors as a Voltage Regulator

People, all the time, use a simple resistor-based voltage divider to change 5v into 3.3v. You see it all over the place. For instance, when you want to get your 5V Arduino to communicate with a 3.3V ESP8266 - you use two resistors (10K and 22K say) to drop the 5V of the Arduino down to the 3.3V the ESP8266 expects.

And that is all fine and dandy.

Dangers of Counterfeit Power Supplies

I thought I would take a look inside a power supply that I suspected was a counterfeit. See just what is going on with it.  This Samsung power supply was making strange things happen with my phone while it was plugged in. Yes, it charged the phone fine, but it made the touch screen go all screwy, and I suspected it was a rather noisy switcher in it. I had bought it from eBay for next to nothing, so I am expecting it to be somewhat nasty inside.

Guess what? I was right.

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