Coroutines in one page of C
A coroutine is a function that you can jump back into after returning from it - and it remembers where it was in the code, and all the variables. This is very useful at times.
One use is generating a sequence of values. Here's how you can generate all the x,y pairs in a 2D range in Python:
def iterate(max_x, max_y): for x in range(max_x): for y in range(max_y): yield x,y for x,y in iterate(2,2): print x,yThis prints:
0 0 0 1 1 0 1 1The yield keyword is like...
Code Metrics - SLOC Count
Many programmers will start having flashbacks at the title of this article because it contains the words 'metrics' and 'SLOC'. Newer programmers are probably wondering what all of the fuss is about - most probably have no negative connotations with the term 'code metrics' and some may not even know what SLOC is. While there is much baggage associated with metrics and SLOC you shouldn't be afraid to gather fundamentally useful data such as SLOC count from your programming projects...
[ C Programming Techniques: integer type optimization ]
I am currently working on a voltage controller running on a ATMEGA328P, ATMEL AVR 8 bits microcontroller. The controller logic is implemented in the main() routine and relies on a periodical timer whose frequency is fixed at application setup. Among other things, the timer ISR handler increments some per tick counters which are then used by the main routine to implement the voltage controller timing logic.By looking at the code, one noticed that I use the uint8_t type for counters instead of...
Interfacing LINUX with microcontrollers
IntroductionI am increasingly asked to work on small spare time projects where a user needs to control some device over the INTERNET. Recently, a friend needed to control heater relays and measure the temperature of its geographically distant secondary house. Another case relates to the control of a pan tilt home monitoring camera. A last one is the control of an old XY plotter DACs.
In both applications, the user wants to access the system over a web browser using HTTP. From the user...
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...
Data Hiding in C
Strictly speaking, C is not an object-oriented language. Although it provides some features that fit into the object-oriented paradigm it has never had the full object-oriented focus that its successor C++ offers. C++ introduced some very useful concepts and abilities that I miss when I’m developing in ANSI C. One such concept is protected member variables and functions.
When you declare a class in C++ you can also declare member variables and functions as part of that class. Often, these...
Chebyshev Approximation and How It Can Help You Save Money, Win Friends, and Influence People
Well... maybe that's a stretch. I don't think I can recommend anything to help you win friends. Not my forte.
But I am going to try to convince you why you should know about Chebyshev approximation, which is a technique for figuring out how you can come as close as possible to computing the result of a mathematical function, with a minimal amount of design effort and CPU power. Let's explore two use cases:
- Amy has a low-power 8-bit microcontroller and needs to compute \( \sqrt{x} \)...
Welcome to my life!
Hi folks!
As an electronic engineer the most of my work is about making new designs where a microcontroller is present in 99.9 % of the applications. Since 2003 I am self-employed and do consultants work for different companies. I have been traveling to different parts of the world doing work for DeLaval International, a company that makes automation equipment for the dairy industry. A lot of the things I have done for them involves use of different Atmel AVR...
10 Software Tools You Should Know
Unless you're designing small analog electronic circuits, it's pretty hard these days to get things done in embedded systems design without the help of computers. I thought I'd share a list of software tools that help me get my job done. Most of these are free or inexpensive. Most of them are also for working with software. If you never have to design, read, or edit any software, then you're one of a few people that won't benefit from reading this.
Disclaimer: the "best" software...
Lightweight hardware abstraction
Some lessons are tougher than others to master. You would think that hard fought battles would be easier to remember, but sometimes it just does not work that way. Recently, I was asked to pick-up a project that had been managed by another employee. The project was yet another cost reduction project. The hardware group was tasked with updating a currently shipping product, to reduce the existing failure rate, while at the same time to remove cost from the...
Product quality: belief or proof?
Embedded software development is a challenging activity, so it is essential to have tools and IP that is of the best quality. However, assessing that quality can be, in itself, a challenge.
Tenderfoot: Introduction to Magic (Numbers that is...)
Once upon a time, while participating in a source code review, I stumbled across the following C code in a header file:
struct Foo { //various structure fields char string_buffer[45+3]; //buffer requires about 45 bytes };My right eyebrow raised, I took a note, and continued with the code review, only to later stumble into this line of code in the body of a C function:
char * temp_string_buffer = (char*) malloc(45+3);Again, I took a note on this function, and continued...
Small or fast?
Developers of software for desktop computers take code optimization for granted. Embedded developers typically need to pay much more attention to the details
Embedded Software Creation I - Methodologies
The first knowledge we need it is to know the posibilities or methodologies that exists to create Software. Each methodology is used to develop diferent types of Software. The types usually are defined by the requeriments and the diferent normative that is related to the type of device. In the next post I will explain how to find the normative@ legislation (link), and how does it work.
Let's start with methodologies. There are lot's of methodologies and so many people that develop...
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...
A wireless door monitor based on the BANO framework
IntroductionI have been thinking for a while about a system to monitor the states of my flat and my garage doors from a remote place. Functionnaly, I wanted to monitor the state of my doors from a remote place. A typical situation is when I leave for holidays, but it can also be useful from the work office. To do so, I would centralize the information on a server connected on the Internet that I could query using a web browser. The server itself would be located in the appartement, where...
More than just a pretty face - a good UI is essential
A user interface can make or break a device - determining its success in the marketplace. With careful design, the UI can make the product compelling and result in a high level of satisfaction from new and experienced users.
Debugging DSP code.
I am fascinated with neural network processing and have been playing with them since the 80's.
I am a frequent contributor to the Numenta forum. Numenta is the current project of Jeff Hawins, the guy that gave us the Palm Pilot. They are working with the HTM model. This is a system based on studies of the functions of the cortical column and has some very interesting properties: It processes sequential data streams and has very effective one shot learning. The data is arranged in Sparse...
Designing Embedded System with FPGA - 1
With the introduction of soft processors and related tools (like EDK from Xilinx), implementation of basic embedded system in FPGA is made easy. This requires very little or almost no knowledge of VHDL programming. Actually that’s how I started. If user is interested in taking full advantage of FPGA and its parallel processing power, then yes, detail understanding of soft processor, its peripheral bus and VHDL programming is required.
I will start with...
Kind of Buggy! The state machine fantastic//
Over the years, I have had the opportunity to experience a lot of different kinds of coding mistakes. There were many that most programmers are familiar with, counting errors, indexing errors (the infamous 'off by one' bug), memory space sharing errors (A threading issue) as well as numerous others. I ran into one recently that I wound up using an old trick to help find.
My current project is a Pan/Tilt camera that was, upon occasion, not homing properly in one axis. The camera is a...
Core competencies
Creating software from scratch is attractive, as the developer has total control. However, this is rarely economic or even possible with complex systems and tight deadlines.
Embedded Software Creation II - European Normative & Legislation
In this post I will explain the European Normative. I will answer the main questions and I will be open to answer all the doubts any of you could have. Please leave a comment and I will answer if i could.
Why I need to look and accomplish some standards?The main reason is if you want to comercialize the product in the European Union, if exists any European Directive that cover the product, the product must be marked with the CE mark. For USA it work in the same way by the...
Debugging DSP code.
I am fascinated with neural network processing and have been playing with them since the 80's.
I am a frequent contributor to the Numenta forum. Numenta is the current project of Jeff Hawins, the guy that gave us the Palm Pilot. They are working with the HTM model. This is a system based on studies of the functions of the cortical column and has some very interesting properties: It processes sequential data streams and has very effective one shot learning. The data is arranged in Sparse...
Hidden Gems from the Embedded Online Conference Archives - Part 2
A look back at a deep dive into the Mars Perseverance flight software from one of the technical leads at JPL.
Thumb Rules for Effective Meetings
Meetings are unavoidable at any work place. At most occasions, meetings can be frustrating. We all face meeting-nightmares in our professional life.
I worked on a project, where none of the team-members were ever interested in any kind of group discussion or formal communication. At early stages of the project, no one wanted to be a part of decision making process. During middle-stages of the project, no one wanted to share any status updates or discuss any critical issues. And finally when...
There are 10 kinds of people in the world
It is useful, in embedded software, to be able to specify values in binary. The C language lacks this facility. In this blog we look at how to fix that.
A true pioneer passes away... A farewell to Ritchie.
We all have our heroes. We all have people who were important to our professional developments. For me, Dennis Ritchie was one of those people. I was an early adopter of the C programming language. Back in the very early 80's a friend and neighbor had excitedly shared with me his copy of "The C Programming Language" by Kernighan and Ritchie. At first I was a non-believer. I had for several years been a happy and productive assembly language...
Tracing code and checking timings
Debugging resource limited systemsApplications writers that write code on large systems have it easy. Well, perhaps not easy, but certainly easier. There are some things that they don't have to worry about and there is a huge array of tools available to them when it comes time to debug. The have choices in their toolsets, lots of choices. They also have a large selection of available methods for getting debugging information out to them such as log files, proc entries, pop up dialog boxes or...
Building Linux Kernel for Desktops
Linux Development has made an amazing process in last decade. Different Linux Distributions come with specific tools which greatly ease down the build process for Linux Kernel.
Here is a good introduction to these build tools and build procedure for different Linux Distributions:
Embedded Software Creation I - Methodologies
The first knowledge we need it is to know the posibilities or methodologies that exists to create Software. Each methodology is used to develop diferent types of Software. The types usually are defined by the requeriments and the diferent normative that is related to the type of device. In the next post I will explain how to find the normative@ legislation (link), and how does it work.
Let's start with methodologies. There are lot's of methodologies and so many people that develop...
