My application on the beaglebone black are multithread and for the
reception there is a thread. And I don't have any problem receiving data on
this thread. Don't forget to use mutex and semaphore.
Le mer. 27 juil. 2016 12:11, William Hermans <yyrk...@gmail.com> a écrit :
> If I recall correctly, typically anything that is related to interrupts,
> and blocking file reads( things of this nature - where you're waiting ) are
> not thread safe as these types of calls can be preempted by another thread.
> So, what I'd do to test if my assumption is correct. Is to write a test
> app without threading. Or perhaps write a callback, but again, callbacks
> are definitely not thread safe.
>
> I'm not seeing all the posts in this discussion for some reason. But is
> there a specific reason why you need threads ? Because if you need this
> sort of process segregation, it may be best to run entirely different
> processes( multiple executables ), and then use some form of IPC mechanism
> such as shared memory. Which POSIX shared memory really is fairly simple
> once you become familiar with it. I had to do this with an application I
> wrote several months back ,myself. Since a library I was using used
> callbacks extensively and was not playing nicely on the stack ( preempting
> my own code routinely ).
>
> On Wed, Jul 27, 2016 at 2:49 AM, Regina Choi <rejina.cho...@gmail.com>
> wrote:
>
>>
>> I'm not aware of library functions that are not thread safe, can you give
>> some example library function that is not thread safe? So if the library
>> function is not thread safe, what would be the effect if we accidentally
>> use it in our program?
>>
>> Does that means we cannot use the library function completely in pthread
>> if it is not thread safe and resort to polling mechanism?
>>
>>
>>
>> On Wednesday, July 27, 2016 at 1:00:10 PM UTC+8, William Hermans wrote:
>>>
>>> Are you sure everything you're using code wise is thread safe ? There
>>> are a lot of library functions that are not thread safe.
>>>
>>> On Mon, Jul 25, 2016 at 8:31 PM, Regina Choi <rejina...@gmail.com>
>>> wrote:
>>>
>>>> Thanks for reply.
>>>>
>>>> I'm not sure why, but I don't get timeout error messages from the read
>>>> thread (though I have set it to 1 sec) !? It just freeze there waiting for
>>>> UART input, even though there are UART input coming in.
>>>>
>>>> Yes, I got the Byte sent message printf from TX thread. Please see the
>>>> attachement.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Jul 26, 2016 at 2:30 AM, Wally Bkg <wb666...@gmail.com> wrote:
>>>>
>>>>> I'm stumped. Are you now getting timeout error messages from the read
>>>>> thread?
>>>>>
>>>>> Are you getting the Byte sent: message printf from the TX thread?
>>>>>
>>>>>
>>>>> On Sunday, July 24, 2016 at 10:11:57 PM UTC-5, Regina Choi wrote:
>>>>>>
>>>>>>
>>>>>> Apology for late reply.
>>>>>>
>>>>>> I've tried with options.c_cc[VMIN] = 0; it's still the same issue.
>>>>>>
>>>>>> From the datasheet of AM335x, uart rx/tx buffers are 64 bytes.
>>>>>>
>>>>>> I've also tried putting tx command in tx thread that activated later
>>>>>> than rx thread. Nothing changed as well.
>>>>>>
>>>>>> void* uartTxWait(void *param){
>>>>>>
>>>>>> int count;
>>>>>> usleep(1000000);
>>>>>> unsigned char cmd[] = {0x10, 0x00, 0x32}; //"Tx From
>>>>>> Beaglebone ";
>>>>>>
>>>>>> if ((count = write(file, (char*)cmd, 3))<0){
>>>>>> perror("Failed to write to the output\n");
>>>>>> //tcsetattr(file, TCSAFLUSH, &oriopt); //before
>>>>>> exit, undo raw setting
>>>>>> //return -1;
>>>>>> }else{
>>>>>> printf("Byte sent: %d \n", count);
>>>>>> }
>>>>>>
>>>>>>
>>>>>> pthread_exit(0);
>>>>>> }
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Friday, July 22, 2016 at 10:50:52 PM UTC+8, Wally Bkg wrote:
>>>>>>>
>>>>>>> I noticed you have options.c_cc[VMIN] = 2; If for some reason only
>>>>>>> one character comes in, it'll block forever. Try using
>>>>>>> options.c_cc[VMIN]
>>>>>>> = 0; so that each char can timeout if its not received.
>>>>>>>
>>>>>>> How big are the Beaglebone uart buffers?
>>>>>>>
>>>>>>> You may still have a race between your write of the data and
>>>>>>> starting your RX thread. Try putting the write into your TX thread and
>>>>>>> launch it after you've launched the RX thread.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Thursday, July 21, 2016 at 10:10:11 PM UTC-5, Regina Choi wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> Hi Wally,
>>>>>>>>
>>>>>>>> I have tried adding fflush(stdout and fflush(stderr) in the while
>>>>>>>> loop, however, in the UartRxWait thread, the read( ) function is in
>>>>>>>> block
>>>>>>>> waiting for incoming data. Which doesn't output anything. In the case,
>>>>>>>> after start and shut down minicom, the UartRxWait thread running as
>>>>>>>> usual,
>>>>>>>> there is no output from the fflush(stdout) and fflush(stderr) either.
>>>>>>>>
>>>>>>>> yes, at the moment I have to kill the program to terminate. I have
>>>>>>>> modified the code such that it loop for only 5 times and terminate the
>>>>>>>> thread.
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>> For more options, visit http://beagleboard.org/discuss
>>>>> ---
>>>>> You received this message because you are subscribed to a topic in the
>>>>> Google Groups "BeagleBoard" group.
>>>>> To unsubscribe from this topic, visit
>>>>> https://groups.google.com/d/topic/beagleboard/p_v98aypDfk/unsubscribe.
>>>>> To unsubscribe from this group and all its topics, send an email to
>>>>> beagleboard...@googlegroups.com.
>>>>> To view this discussion on the web visit
>>>>> https://groups.google.com/d/msgid/beagleboard/16a9b1d0-6c0e-4b31-ac7f-490bc091f751%40googlegroups.com
>>>>> <https://groups.google.com/d/msgid/beagleboard/16a9b1d0-6c0e-4b31-ac7f-490bc091f751%40googlegroups.com?utm_medium=email&utm_source=footer>
>>>>> .
>>>>>
>>>>> For more options, visit https://groups.google.com/d/optout.
>>>>>
>>>>
>>>> --
>>>> For more options, visit http://beagleboard.org/discuss
>>>> ---
>>>> You received this message because you are subscribed to the Google
>>>> Groups "BeagleBoard" group.
>>>> To unsubscribe from this group and stop receiving emails from it, send
>>>> an email to beagleboard...@googlegroups.com.
>>>> To view this discussion on the web visit
>>>> https://groups.google.com/d/msgid/beagleboard/CAJ5%2BLfyKahyeih3Db50ZP7yOiLPUyKt0f6sn7dwnijJ6gEx07Q%40mail.gmail.com
>>>> <https://groups.google.com/d/msgid/beagleboard/CAJ5%2BLfyKahyeih3Db50ZP7yOiLPUyKt0f6sn7dwnijJ6gEx07Q%40mail.gmail.com?utm_medium=email&utm_source=footer>
>>>> .
>>>>
>>>> For more options, visit https://groups.google.com/d/optout.
>>>>
>>>
>>> --
>> For more options, visit http://beagleboard.org/discuss
>> ---
>> You received this message because you are subscribed to the Google Groups
>> "BeagleBoard" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to beagleboard+unsubscr...@googlegroups.com.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msgid/beagleboard/9d7676da-fb51-4ea2-b378-77486ba052bd%40googlegroups.com
>> <https://groups.google.com/d/msgid/beagleboard/9d7676da-fb51-4ea2-b378-77486ba052bd%40googlegroups.com?utm_medium=email&utm_source=footer>
>> .
>>
>> For more options, visit https://groups.google.com/d/optout.
>>
>
> --
> For more options, visit http://beagleboard.org/discuss
> ---
> You received this message because you are subscribed to the Google Groups
> "BeagleBoard" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to beagleboard+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/beagleboard/CALHSORrX555JB43Db_bsajqhGD_nnSOKx8NmoUAnDbjF7HUubQ%40mail.gmail.com
> <https://groups.google.com/d/msgid/beagleboard/CALHSORrX555JB43Db_bsajqhGD_nnSOKx8NmoUAnDbjF7HUubQ%40mail.gmail.com?utm_medium=email&utm_source=footer>
> .
> For more options, visit https://groups.google.com/d/optout.
>
--
For more options, visit http://beagleboard.org/discuss
---
You received this message because you are subscribed to the Google Groups
"BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to beagleboard+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/beagleboard/CAF%2BMRtkeVNY5Nb6jOL2ztLTyMhc2E8x_xLghnDe_rgjKgU-YtA%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.
