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  1. Like
    NicholasLindan got a reaction from Markel in Powering ST LSM303AGR from MCU IO Pin   
    I've done this on products - powered an analog section off an I/O pin.  It is the cheapest power control method - heck it's free and it takes no power to implement.
    If you need more current you can parallel two or more pins.  There is no problem with parallel MOSFETs, they will current share as rdson increases with temperature.
  2. Like
    NicholasLindan got a reaction from agaelema in Announcing the PRTOS preemptive real time operating system   
    Announcing the release PRTOS, an open-source preemptive real time operating system kernel for bare-metal applications.
    You may find PRTOS a good choice if you want to learn about preemptive multitasking.  The API, though having all the features of FreeRTOS or uC/OS, is much simpler and easier to learn.  Additionally the system will fit into much smaller processors.
    PRTOS is released by Cleveland Engineering Design - the developer of the CoRTOS cooperative real time OS, also available on Sourceforge.
    PRTOS presently supports the MSP430 and AVR architectures.
    PRTOS is available on Sourceforge at https://sourceforge.net/projects/prtos-preemptive-rtos/
    The advantages of PRTOS are:
      It has the smallest footprint of any true preemptive system: 1.3kB for basic scheduling and task control, 4.8kB with all the features below (MSP430 / size optimization);   Only 950 lines of code implement all of the RTOS features (SLOC-L);   The system is configurable, you include only the features you need;   There is minimal to zero interrupt burden;   The system is well documented with a short but comprehensive manual, well-commented source code, and a test suite demonstrating the features;   The system is proven - it has been in use since 1982 with applications in in-vitro medical equipment, process control instrumentation and industrial machinery;   It is released under a GPL V3 license and commercial licensing is available. PRTOS provides the following features:
      Preemptive   Prioritized   Round-robin equal priority tasks Task Control
      Initialize/Ready   Suspend/Resume   Lock/Unlock   Change priority   Relinquish a round-robin turn Communication
      Messages, priority messages   Signals Delay & Time
      Task delays   Time-outs   Periodic signals   Run timers Resources  (mutexes)
      Multiple resource ownership   Priority inversion mitigation   Priority or FIFO queuing Semaphores
      Binary   Counting   Signaling ISR -> task functions
      Send signal   Send message, send priority message   Resume task  
  3. Like
    NicholasLindan got a reaction from bluehash in CoRTOS: An open source minimalist RTOS   
    CoRTOS is a Cooperative Real Time Operating System for bare-metal applications.
    Its advantages over other systems are that it is fully documented with a manual and examples, is easy to understand and use and is astonishingly simple: The kernel is just 16 lines of C.  The CoRTOS module compiles to ~200 bytes of code.  The system includes optional modules implementing delays, timers, messaging, mutexes and signaling. It is intended for smaller microprocessors, such as the MSP430, Cortex M0+, AVR and PIC24, and for smaller systems of maybe a dozen tasks.

    CoRTOS is not a task scheduler.

    CoRTOS works like any other RTOS. Tasks schedule themselves, picking up where they left off after making a call to the OS.

    Please feel free to send questions to nolindan@ix.netcom.com

    The intended audience includes:
    • Those needing a small footprint RTOS;
    • Students learning about real time systems;
    • Makers wanting to program "close to the metal"
    World's simplest RTOS CoRTOSV1d.zip
  4. Thanks
    NicholasLindan got a reaction from Fmilburn in CoRTOS: An open source minimalist RTOS   
    I know that every time I grab code I edit it so it conforms to my needs, prejudices and sensibilities -- that makes the code mine, in a sense, and less foreign - and as I make the changes I get to mutter under my breath about the original author: "Bloody fool, what does he think he is doing."  I expect any one using CoRTOS will want to and have to change it in some way and utter their own mutterings.
    So please, make changes to your heart's content with the source.  In any work, everyone finds something to disagree on.  What some find terminally annoying others find full of virtue. I can't please everyone and I'm not going try.  That path is the surest way to please no one.
    The Shakers would put a purposeful gouge in their furniture lest their attempt at perfection offend God.  I leave plenty of gouges in my work.
    As the manual states: "Worth price charged."
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