Intro to Microcontrollers Part 2: AVR Microcontrollers
Introduction
This is part 2 of my playing around with AVR microcontrollers. Last time, I had a basic setup which could program an AVR using the Arduino ISP. I used it to drive a simple 7-segment, multiplexed 4-digit LED display. This is a follow up where I try out some of the other features the ATTiny24A has to offer. I also decided to invest some money in an AVR Dragon programmer/debugger so I'll go over some basic playing and setup with this device. I'll also discuss some of the problems...
MSP430 LaunchPad Tutorial - Part 4 - UART Transmission
Today we are going to learn how to communicate using UART with the Launchpad. For this purpose I will replace the default microcontroller that comes with the board with the MSP430G2553. It is the most powerful device in the MSP430 Value Line and it comes with an integrated hardware UART module, along with 16 Kb of Flash memory, 512 bytes of SRAM and an 8-channel, 10 bit ADC.
UART communication can be useful when dealing with sensors: as a basic example, we could...
MSP430 LaunchPad Tutorial - Part 3 - ADC
In this new episode of our journey into MSP430 I will explain the basics of Analog to Digital Conversion on the MSP430G2231.We will write a program that will read an ADC channel and will toggle some leds based on the result of the conversion.
We start as usual with the inclusion of the header file for the MSP430G2231, the leds stuff and with the definition of a variable that will store the result of the conversion. We also declare a function that will initialize the ADC...
MSP430 Launchpad Tutorial - Part 2 - Interrupts and timers
What is an "interrupt"? It is a signal that informs our MCU that a certain event has happened, causing the interruption of the normal flow of the main program and the execution of an "interrupt routine", that handles the event and takes a specified action.
Interrupts are essential to avoid wasting the processor's valuable time in polling loops, waiting for external events (in fact they are used in Real-Time Operating Systems,
An Introduction to Embedded Development
This blog is a series to provide an introduction to embedded development for the aspiring embedded developer. No prior embedded development experience will be assumed, but you should have a reasonable understanding of the C language and knowledge of basic electronics. It will focus on the TI MSP430, but present topics in a generic way that can be easily translated to other processors. Welcome!Hello, and welcome to my blog! This blog will be somewhat different from most...
MSP430 Launchpad Tutorial - Part 1 - Basics
TI's LaunchPad is a complete MSP430 development environment: all you have to do is download and install CCS IDE (login required), connect your G2231-ready LaunchPad to your computer with the included mini-usb cable, and you are ready to code!
Texas Instrument MSP430 LaunchPadSo, let's see how to start a new project in Code Composer Studio. This IDE is derived from Eclipse, so if you used it before you shouldn't have much problems.
We'll write a simple program that will...
Endianness and Serial Communication
Endianness is a consideration that is easily overlooked in the design of embedded systems. I myself am amply guilty of this oversight. It’s something you don’t ever have to worry about if you’re only working with a single processor or two processors that have the same endianness. You can even avoid it if you have two processors that have different endianness but never transmit data between themselves that consists of more than one byte. It’s easy to lull...
C Programming Techniques: Function Call Inlining
Introduction
Abstraction is a key to manage software systems as they increase in size and complexity. As shown in a previous post, abstraction requires a developper to clearly define a software interface for both data and functions, and eventually hide the underlying implementation.When using the C language, the interface is often exposed in a header '.h' file, while the implementation is put in one or more corresponding '.c' files.
First, separating an interface from its...
Debugging with Heartbeat LEDs
In this article I’ll discuss one of the most basic debugging tools in an embedded system: the heartbeat LED. Picture this: you’re developing your first program for a new microcontroller. You’ve written the code, configured the programmer, downloaded the HEX file and now... what Your program is running - isn’t it?
Truth is that it’s hard to tell with most embedded software. Compared to desktop or even server applications embedded software tend not to have very many...
Layout recomendations and tips for best performance against EMC
When making the layout of the circuit diagram, it is interesting to perform a preliminary analysis of several issues in order to minimize problems arising from electromagnetic compatibility.The analysis consists in:
Identify / Analyze components: This section will analyze the integrated components, as well as any recommendations it may have the manufacturer. We must also analyze the encapsulation possibilities which have the component.
C++ on microcontrollers 4 – input pins, and decoding a rotary switch
This blog series is about the use of C++ for modern microcontrollers. My plan is to show the gradual development of a basic I/O library. I will introduce the object-oriented C++ features that are used step by step, to provide a gentle yet practical introduction into C++ for C programmers. Reader input is very much appreciated, you might even steer me in the direction you find most interesting.
So far I...
C Programming Techniques: Function Call Inlining
IntroductionAbstraction is a key to manage software systems as they increase in size and complexity. As shown in a previous post, abstraction requires a developper to clearly define a software interface for both data and functions, and eventually hide the underlying implementation.When using the C language, the interface is often exposed in a header '.h' file, while the implementation is put in one or more corresponding '.c' files.
First, separating an interface from its...
Practical CRCs for Embedded Systems
CRCs are a very practical tool for embedded systems: you're likely to need to use one as part of a communications protocol or to verify the integrity of a program image before writing it to flash. But CRCs can be difficult to understand and tricky to implement. The first time I attempted to write CRC code from scratch I failed once. Then twice. Then three times. Eventually I gave up and used an existing library. I consider myself intelligent: I got A's...
Introduction to Microcontrollers - More Timers and Displays
Building Your World Around Timers
By now you have seen four different ways to use timers in your programs. Next we will look at some ways to produce the effect of multiple parallel streams of work in your program with the help of timers. This effect is only an appearance, not a reality, since a single microcontroller (one core) can only run a single thread of code. However, since microcontrollers are so fast in relation to a great many of the tasks to...
Energia - program a TI MSP430 using Arduino sketches
TI MSP430 Launchpad
I started tinkering with microcontroller a couple of years ago with an Arduino Uno. I had a little experience with C, so programming in the Arduino environment has been relatively easy and straightforward for me. My code is not necessarily elegant or efficient, but I can usually figure out how to make an Arduino do what I want it to do eventually. A lot of credit to the Arduino userbase, as it is very easy to figure most things out with a quick Google...
Debugging with Heartbeat LEDs
In this article I’ll discuss one of the most basic debugging tools in an embedded system: the heartbeat LED. Picture this: you’re developing your first program for a new microcontroller. You’ve written the code, configured the programmer, downloaded the HEX file and now... what Your program is running - isn’t it?
Truth is that it’s hard to tell with most embedded software. Compared to desktop or even server applications embedded software tend not to have very many...
Using XML to describe embedded devices (and speak to them)
This article discusses one of the typical development cycles in embedded device and communication design and presents a possible, light weight solution using the free DClib/netpp framework.
The challengeAssume we're faced with the design of an embedded device, be it a simple SoC unit or a more complex, uC controlled engine with various attached peripherals. From first prototype to the market, the following development cycle is typically walked through:
Introduction to Microcontrollers - Adding Some Real-World Hardware
When 2 LEDs Just Don't Cut It AnymoreSo far, we've done everything in this series using two LEDs and one button. I'm guessing that the thrill of blinking an LED has worn off by now, hard as that is to imagine. What's more, we've just about reached the limits of what we can learn with such limited I/O. We have come to the point where we need to add some hardware to our setup to continue with additional concepts and microcontroller...
Favorite Tools: C++11 std::array
Many embedded software and firmware projects must be developed to high standards of reliability. To meet these reliability requirements, firmware project teams will consider many design tradeoffs. For example, an engineering team may avoid or outright ban the use of dynamic memory allocation, a feature typically accessed via the C library call "malloc" or the C++ allocator "new". When authoring software under such...
Coding Step 3 - High-Level Requirements
Articles in this series:
- Coding Step 0 - Development Environments
- Coding Step 1 - Hello World and Makefiles
- Coding Step 2- Source Control
- Coding Step 3 - High-Level Requirements
- Coding Step 4 - Design
If this series of articles has been light on one thing it's 'coding'. If it's been light on two things the second is 'embedded'. In three articles I haven't gotten past Hello World on a desktop PC. That changes (slowly) with this article. In this article I'll...
Introduction to Microcontrollers - Adding Some Real-World Hardware
When 2 LEDs Just Don't Cut It AnymoreSo far, we've done everything in this series using two LEDs and one button. I'm guessing that the thrill of blinking an LED has worn off by now, hard as that is to imagine. What's more, we've just about reached the limits of what we can learn with such limited I/O. We have come to the point where we need to add some hardware to our setup to continue with additional concepts and microcontroller...
Cortex-M Exception Handling (Part 2)
The first part of this article described the conditions for an exception request to be accepted by a Cortex-M processor, mainly concerning the relationship of its priority with respect to the current execution priority. This part will describe instead what happens after an exception request is accepted and becomes active.
PROCESSOR OPERATION AND PRIVILEGE MODEBefore discussing in detail the sequence of actions that occurs within the processor after an exception request...
How to Arduino - a video toolbox
I've begun producing a new series of video tutorials for the hobbyist new to the Arduino or microcontrollers in general. My videos are very pragmatic - I prefer to answer the question "what is the quickest, simplest and most affordable way to accomplish this?". The videos are meant to be a quick source of "how to" knowledge for the hobbyist that is using an LCD display, ultrasonic sensor or accelerometer for the first time, for example. I hope you enjoy this series of...
Real-time clocks: Does anybody really know what time it is?
We recently started writing software to make use of a real-time clock IC, and found to our chagrin that the chip was missing a rather useful function, namely elapsed time in seconds since the standard epoch (January 1, 1970, midnight UTC).Let me back up a second.A real-time clock/calendar (RTC) is a micropower chip that has an oscillator on it that keeps counting time, independent of main system power. Usually this is done with a lithium battery that can power the RTC for years, so that even...
C++ on microcontrollers 2 - LPCXpresso, LPC-link, Code Sourcery, lpc21isp, linkerscript, LPC1114 startup
previous parts: 1
This blog series is about the use of C++ for modern microcontrollers. My plan is to show the gradual development of a basic I/O library. I will introduce the object-oriented C++ features that are used step by step, to provide a gentle yet practical introduction into C++ for C programmers. Reader input is very much appreciated, you might even steer me in the direction you find most interesting.
I teach my students that...
Using XML to describe embedded devices (and speak to them)
This article discusses one of the typical development cycles in embedded device and communication design and presents a possible, light weight solution using the free DClib/netpp framework.
The challengeAssume we're faced with the design of an embedded device, be it a simple SoC unit or a more complex, uC controlled engine with various attached peripherals. From first prototype to the market, the following development cycle is typically walked through:
Energia - program a TI MSP430 using Arduino sketches
TI MSP430 LaunchpadI started tinkering with microcontroller a couple of years ago with an Arduino Uno. I had a little experience with C, so programming in the Arduino environment has been relatively easy and straightforward for me. My code is not necessarily elegant or efficient, but I can usually figure out how to make an Arduino do what I want it to do eventually. A lot of credit to the Arduino userbase, as it is very easy to figure most things out with a quick Google...
Introduction to Microcontrollers - More Timers and Displays
Building Your World Around TimersBy now you have seen four different ways to use timers in your programs. Next we will look at some ways to produce the effect of multiple parallel streams of work in your program with the help of timers. This effect is only an appearance, not a reality, since a single microcontroller (one core) can only run a single thread of code. However, since microcontrollers are so fast in relation to a great many of the tasks to...
Favorite Tools: C++11 std::array
Many embedded software and firmware projects must be developed to high standards of reliability. To meet these reliability requirements, firmware project teams will consider many design tradeoffs. For example, an engineering team may avoid or outright ban the use of dynamic memory allocation, a feature typically accessed via the C library call "malloc" or the C++ allocator "new". When authoring software under such...
Coding Step 2 - Source Control
Articles in this series:
- Coding Step 0 - Development Environments
- Coding Step 1 - Hello World and Makefiles
- Coding Step 2 - Source Control
- Coding Step 3 - High-Level Requirements
- Coding Step 4 - Design
When I first started out in programming, version control was not an introductory topic. Not in the least because it required a 'server' (ie, a computer which a teenaged me couldn't afford) but because it seemed difficult and only useful to teams rather than...
