Developing for the Atmel AVR Microcontroller on Linux
Using avr-gdb and simulavr in tandem, you can run your software on a choice of AVR microcontrollers through the simulator, while using GDB to step through and observe the executing code. Acquire the simulavr source from the project site and perform the installation:
$ ./configure --prefix=/usr/local/AVR \ --with-avr-includes=/usr/local/AVR/avr/include $ make # make install
Install GDB, built for AVR targets, by compiling the source as follows:
$ ./configure --target=avr \ --prefix=/usr/local/AVR $ make # make install
When you finally have a program ready for testing on actual hardware, you need some way to upload the data and write it to the microcontroller's Flash program memory. AVRDUDE and a compatible hardware programmer are the last components of the development kit. Grab a copy of the AVRDUDE source and install it with:
$ ./configure --prefix=/usr/local/AVR $ make # make install
You now have installed every software component required for a complete AVR development environment. All you need is the physical means to transfer programs to microcontrollers.
AVRDUDE supports a number of different hardware programmer configurations. The simplest systems are described on the AVRDUDE site and are comprised of little more than a parallel port connector, a ceramic oscillator and a DIP socket. These are powered directly off the computer's port and may not work for everyone.
A step up in complexity, independently powered, buffered in-system programmers can be built easily (see Resources). Two programmers requiring only a few parts are discussed on the Psychogenic Web page, which describes the schematics, provides artwork and has complete instructions on creating your own printed circuit boards (as depicted in Figure 2) for the programmers.
A number of commercial solutions also are available. If you're interested in easily programming a wide selection of the AVR family, go with Atmel's STK500 kit. More than a simple programmer, the STK500 is a starter kit that allows you to program the microcontrollers and easily prototype new designs. It includes a number of LEDs and switches, an oscillator, RS-232 interface and other niceties that easily can be interfaced with your target chip.
Our focus here is on the development system rather than on programming for the AVR platform. The AVR Libc documentation is a good place to start for information on programming AVRs in Assembly, C and C++.
The Hello World program of the microcontroller universe is the classic flashing LEDs. A slightly different take on this theme, which Knight Rider fans should appreciate, is available on the Linux Journal FTP site, where you can download C (Listing 2) or C++ (Listing 3) versions of an example program that cycles each of eight light-emitting diodes (LEDs) back and forth.
Create a project directory—for instance, ~/helloavr/—and retrieve the program, saving Listing 2 as ~/helloavr/kr.c and Listing 3 as ~/helloavr/kitt.cpp. Also, copy the Makefile template, /usr/local/AVR/Makefile.tpl, to ~/helloavr/Makefile.
Using this Makefile is easy and makes compilation a snap. Open the Makefile in your favourite editor and modify the configuration section, near the top of the file, so that the MCU, PROJECTNAME and PRJSRC variables are set as shown in Listing 4. The MCU variable determines the AVR family member for which we are compiling the program, and the PRJSRC variable lists all the Assembly, C and C++ source files used in the project.
Listing 4. HelloAVR Project Makefile Configuration Options
##### Target Specific Details ##### ##### Customize these for your project ##### # Name of target controller # (e.g. 'at90s8515', see the available avr-gcc mmcu # options for possible values) MCU=at90s8515 # Name of our project # (use a single word, e.g. 'myproject') PROJECTNAME=helloavr # Source files # List C/C++/Assembly source files: # (list all files to compile, e.g. 'a.c b.cpp as.S') # Use .cc, .cpp or .C suffix for C++ files, use .S # (NOT .s !!!) for assembly source code files. PRJSRC=kr.c
Once you've configured the Makefile, compiling and linking the program is as simple as typing make.
You can perform the compilation and linking steps manually instead, by issuing:
$ avr-gcc -I. -g -mmcu=at90s8515 -Os \ -fpack-struct -fshort-enums \ -funsigned-bitfields -funsigned-char \ -Wall -Wstrict-prototypes -c kr.c $ avr-gcc -o helloavr.out kr.o
The most notable difference is the addition of the required -mmcu command-line argument, used to specify the target microcontroller. Either method compiles kr.c and creates the helloavr.out ELF-format program. This file cannot be executed on your development station but is used later during the debugging stage.
You also can build the C++ version of the program by doing a make clean, changing the Makefile PRJSRC variable to kitt.cpp and then issuing another make.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Non-Linux FOSS: Caffeine!
- Managing Linux Using Puppet
- Tech Tip: Really Simple HTTP Server with Python
- Parsing an RSS News Feed with a Bash Script
- Google's SwiftShader Released
- SuperTuxKart 0.9.2 Released
- Doing for User Space What We Did for Kernel Space
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide