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Have a question about Micrium's embedded software? Ask our Expert, Matt Gordon

e14 Contributor

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Matt Gordon

Matt Gordon is a senior applications engineer at Micrium.  He began his career developing device drivers, kernel ports, and example applications for Micrium's customers.  Drawing on this experience, Matt has written multiple articles on embedded software.  He also heads Micrium's training program and regularly teaches classes on real-time kernels and other embedded software components.  Matt holds a bachelor's degree in computer engineering from Georgia Tech, Georgia in the USA.


  • Dear Matt,

     

    I'm trying to use uc/os II on a STM32F103, usart communication. Things aren't working at all, and can't find working examples over the net.

    Could you please post some? I've read it's necessary to tell uC that system is entering an isr.

    Regards

     

    Carlos

  • Hello sir,

    I already have an application developed in vb.net 2008 that can detect user's face, but how can i link this with GINA(in winXP) so that i can develop a login system that recognizes users and allows them to login to windows with their face .

    I have browsed several custom GINA sources codes but all speaks in C++ and i know custom GINA can only developed in C++ code.

    Is there anyway i could link GINA to my application written in VB.NET, any function call from a custom GINA or something like that ?

    Can you provided a custom GINA so that i can use this and link to my VB.NET or VB6 or even C# application ?

    I know GINA is used upto win XP only. I just need to implement this feature in an XP machine only nothing beyond that.

    I hope you will be grateful to help me in that direction.

  • Hi Matt,

     

    Hey I have another evalboard form Luminary Micro LM3S3748-IQC50-A0LM3S3748-IQC50-A0 and Iwant to use the OS-III on this board but the ports for this board are not available for using with OS-III. It is supported with OS-II though. What do you suggest that i should do?

     

    Thanks in advance Matt.

     

    Regards,

    jumbowat

  • Hi Matt,

     

    The tasks run only once even if they are run in while(1) or while(DEF_ON)

     

    What should I do if I want to run the tasks infinitely????

     

    Please help.

     

    Kind Regards,

    jumbowat

  • in reply to e14 Contributor

    Technically, just one uC/OS-III port is used for all of the Luminary Micro/TI Stellaris parts; it is a generic Cortex-M3 port.  To run uC/OS-III on the particular board that you have in mind, you will need the kernel's source code and this port.  You will also need a modicum of BSP and application code.  You can get the kernel code (source and port) from an existing uC/OS-III Stellaris project--for instance, the LM3S9B92-based project that was developed for the TI version of Micrium's uC/OS-III book.  You can also borrow your application code from such a project, but this code might need to be modified slightly to suit your platform.  As for the BSP, you should be able to reuse the code from the uC/OS-II project that you mentioned.

  • in reply to e14 Contributor

    In uC/OS-II and uC/OS-III, a task containing an infinite loop should run periodically.  The only tasks that should run just once are those that are deleted via OSTaskDel(). 

     

    Regards,

     

    Matt

  • in reply to e14 Contributor

    The projects that were developed for the STM32 version of Micrium's uC/OS-III book contain USART code that could serve as your template.  You can download these projects from the knode: http://www.element14.com/community/docs/DOC-36991/l/micrium-ucos-iii-project-for-stmicro-cortex-m3-stm32f107. 

     

    Regards,

     

    Matt

  • Hi Matt,

     

    You have been a great help, just one little thing, how to use the flags in uC/OS-III. I define the bits, create the flag, pend the flag and after the task is executed I post the flag, but I guess its not as simple as using a semaphore, beacuse its not working. Please help Matt. image

     

    Regards,

    jumbowat

  • in reply to e14 Contributor

    To some extent, event flags are like collections of binary semaphores.  Each flag represents an event and can be in one of two possible states: the event has taken place, or it hasn’t.  Your application can wait on these events using a pend function similar to the one provided as part of uC/OS-III’s semaphore API. 

     

    The pend function, which is named OSFlagPend(), accepts a number of arguments, the second of which is a bit pattern indicating the particular flags that are of importance to the calling task.  The function also accepts an options value that allows the calling task to specify whether it will wait for all (an “and” pend) or any (an “or” pend) of the designated events to take place.  A return from the pend function typically occurs once the conditions established by the calling task through these two arguments have come into existence.  However, the calling task can use another of the function’s arguments to specify a timeout, a period of time after which the function will return regardless of which events have taken place. 

     

    The pend function’s counterpart is the event flag post function, OSFlagPost().  Like pend, this function accepts an argument that specifies a set of flags.  In the case of post, though, the calling task will not wait on these flags; instead, the kernel will update the flags’ values to indicate that the events to which they correspond have taken place. 

     

    Example pend and post calls are shown below.  Additional example code can be found in the uC/OS-III books available from the knode.