Combining Arduino Sketches

Beginners love Arduino coding because there is so much of it available to just copy, load and go without too much thinking required.

Then they find that one thing they want to do is in one sketch and another in a second sketch. All they need to do is combine these sketches! This can be a big hurdle the first time it happens and many fail to get a satisfactorily working product.

There is a systematic approach to this that helps to ensure that things work.

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Finite State Machine Programming Basics – Part 2

The first part of this article introduced a simple Finite State Machine through the exercise of transforming the standard linearly programmed Blink example into a FSM style application.

In this part we’ll look at other common embedded applications and how they can be coded using FSM techniques.

Finite State Machine Programming Basics – Part 1

Many beginner programmers, once they go beyond the ‘blinking LED’ code, get blocked by not being able to do more than one thing at once. In many cases they are directed to the ‘Blink WithOut Delay’ code (BWOD) as a hint about what to do, but this soon also runs out of steam. BWOD implies, but does not make explicit, a Finite State Machines (FSM) approach.

In this article we’ll evolve the simple linear Blinking LED sketch into a FSM to illustrate the difference in approach.

Using the MAX7219 in your Projects – Part 2

In the first part we explored the functions of this MAX7219 and how the SPI link is the key to making the device work for us.

In this part we’ll develop code to efficiently display numeric data using 7-segment and LED matrix displays.

Using the MAX7219 in your Projects – Part 1

The MAX7219 is a common and inexpensive IC used for controlling up to eight 7-segment LED displays (or 64 individual LEDs).

Beginners are often intimidated by how to use this versatile component with a microcontroller, turning to libraries to help them solve the problem. In most simple cases, it is more efficient to run the IC directly. Here’s what you need to know to get the job done.

YX5300 MP3 Player

The YX5300 MP3 module is easily interfaced to a microcontroller, creating MP3 player with a user interface. Using the MD_YX5300 library and an understanding of how the device works (see the previous posts here and here), this article describes the code for a simple MP3 player and a more complex player with an LCD module display.

YX5300 Serial MP3 Player – Message Sequencing

Since my previous YX5300 post I have received a number of questions related to how the serial messages between a host and the MP3 module work. Understanding this message flow is important when writing code that uses the MP3 player in an interactive application.

Persisting Application Parameters in EEPROM

When an application starts, any data was was part of a previous execution is reset to the initialised values of the variables. Often, however, it is desirable to maintain configuration and state values between processor resets. EEPROM is a good option to store these values.

This article explores ways to make this task easy.

Are Strings really that Evil?

One of the many repeating themes on the Arduino forums is the use of Strings (with a capital ‘S’) against usings strings (with a little ‘s’) – the former refers to a class that encapsulates string handling and the latter refers to the use of nul terminated char arrays.

The kind of forum threads involved are generally someone who wants to use Strings and is having a problem followed by a lot of other posts telling them not to because they are ‘bad’.

So what makes them ‘bad’ and is this really a problem?

MPS020N0040D Sensor as a Pressure Activated Switch

The MPS020N0040D pressure sensor is a cheap component readily available for purchase on sites like eBay.

I recently needed to create a blow activated switch and, as I already had a few of these at hand, decided to design a minimal circuit that would provide a digital output when a threshold pressure was detected by the sensor.