Fully automated minimal bare metal blinker example Tested on Ubuntu 16.04 host, Raspberry Pi 2. https://github.com/dwelch67/raspberrypi is the most comprehensive example set I’ve seen to date (previously mentioned on this now deleted answer), but this is a minimal easy to setup hello world to get you started quickly. Usage: Insert SD card on host Make … Read more
I have some preferences (and pet peeves) from writing software to control media and display devices using RS232. Depending on your hardware, some of these may not apply: I think it’s a good idea to make your protocol more friendly for automation. If you need an interactive interface (command line or other), build it separately … Read more
Uninitialized exception vectors (you know, for the ones that “will never be reached”) Say it with me: Global variables. Especially ones shared between ISRs and tasks (or foreground loops) without protection. Failure to use “volatile” where necessary. Having routines that DisableInterrupts() and then EnableInterrupts() paired up. Got that? Not RestoreInterrupts(), but ENABLE. Yeah, nesting. No … Read more
In the C standard, a standalone implementation doesn’t have to provide all of the library functions that a hosted implementation has to provide. The C standard doesn’t care about embedded, but vendors of embedded systems usually provide standalone implementations with whatever amount of libraries they’re willing to provide. C is a widely used general purpose … Read more
A jump table can be either an array of pointers to functions or an array of machine code jump instructions. If you have a relatively static set of functions (such as system calls or virtual functions for a class) then you can create this table once and call the functions using a simple index into … Read more
My experience from an extremely constrained embedded memory environment: Use fixed size buffers. Don’t use pointers or dynamic allocation because they have too much overhead. Use the smallest int data type that works. Don’t ever use recursion. Always use looping. Don’t pass lots of function parameters. Use globals instead. 🙂
I just encountered this problem myself on Windows 7 Professional x64, and a solution that worked for me was to go into the registry and edit the following value: Location: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\sermouse Key: Start Value: 3 Change Value to 4 and it will stop this problem occurring. Here is a list of all valid Start values: … Read more
Exceptions are now well-handled, and the strategies used to implement them make them in fact faster than testing return code, because their cost (in terms of speed) is virtually null, as long as you do not throw any. However they do cost: in code-size. Exceptions usually work hand in hand with RTTI, and unfortunately RTTI … Read more
Lego Mindstorms NXT http://mindstorms.lego.com/ http://en.wikipedia.org/wiki/Lego_Mindstorms_NXT http://nxtnet.codeplex.com/
If the event of interest is: Asynchronous Urgent Infrequent then an interrupt based handler would make sense. If the event of interest is: Synchronous (i.e. you know when to expect it within a small window) Not Urgent (i.e. a slow polling interval has no ill effects) Frequent (i.e. majority of your polling cycles create a … Read more