Lower priority task with getchar() halts higher task in FreeRTOS

Lower priority task with getchar() halts higher task in FreeRTOS - how to fix that?

I have two functions:

shell() uses getchar() to get user input

playLED() plays a LED animation

I have two tasks running in FreeRTOS

    xTaskCreate(

                    shell,

                    "shell",

                    512,

                    NULL,

                    1,

                    NULL);



    xTaskCreate(

                    playLED,

                    "playLED",

                    512,

                    NULL,

                    15,

                    NULL );

    vTaskStartScheduler();

Then I noticed the LED animation play become step-wise, it changes only when getchar() received input from user, instead of a smooth animation.

I've already set LED priority a lot higher, however this didn't fix the halt. Is there anything else that I should configure somewhere?

The code is run on NXP LPC54018 board with MCUXpresso. A similar problem on a different device can be found at https://os.mbed.com/questions/781/Skip-getchar-if-no-input-using-interrupt/

edited Oct 29 '18 at 18:02

asked Oct 27 '18 at 0:08

Suicide Bunny

142110

Can you better describe your environment (CPU, libraries, µC, toolset)? getchar() is not part of FreeRTOS. So only answers specific to your environment can be given.

– Codo
Oct 27 '18 at 9:17

Thanks for the reply. I am using it with a MCUxpresso on NXP LPC 54018

– Suicide Bunny
Oct 29 '18 at 17:59

add a comment |

I have two functions:

shell() uses getchar() to get user input

playLED() plays a LED animation

I have two tasks running in FreeRTOS

    xTaskCreate(

                    shell,

                    "shell",

                    512,

                    NULL,

                    1,

                    NULL);



    xTaskCreate(

                    playLED,

                    "playLED",

                    512,

                    NULL,

                    15,

                    NULL );

    vTaskStartScheduler();

Then I noticed the LED animation play become step-wise, it changes only when getchar() received input from user, instead of a smooth animation.

I've already set LED priority a lot higher, however this didn't fix the halt. Is there anything else that I should configure somewhere?

The code is run on NXP LPC54018 board with MCUXpresso. A similar problem on a different device can be found at https://os.mbed.com/questions/781/Skip-getchar-if-no-input-using-interrupt/

edited Oct 29 '18 at 18:02

asked Oct 27 '18 at 0:08

Suicide Bunny

142110

Can you better describe your environment (CPU, libraries, µC, toolset)? getchar() is not part of FreeRTOS. So only answers specific to your environment can be given.

– Codo
Oct 27 '18 at 9:17

Thanks for the reply. I am using it with a MCUxpresso on NXP LPC 54018

– Suicide Bunny
Oct 29 '18 at 17:59

add a comment |

I have two functions:

shell() uses getchar() to get user input

playLED() plays a LED animation

I have two tasks running in FreeRTOS

    xTaskCreate(

                    shell,

                    "shell",

                    512,

                    NULL,

                    1,

                    NULL);



    xTaskCreate(

                    playLED,

                    "playLED",

                    512,

                    NULL,

                    15,

                    NULL );

    vTaskStartScheduler();

Then I noticed the LED animation play become step-wise, it changes only when getchar() received input from user, instead of a smooth animation.

I've already set LED priority a lot higher, however this didn't fix the halt. Is there anything else that I should configure somewhere?

The code is run on NXP LPC54018 board with MCUXpresso. A similar problem on a different device can be found at https://os.mbed.com/questions/781/Skip-getchar-if-no-input-using-interrupt/

edited Oct 29 '18 at 18:02

asked Oct 27 '18 at 0:08

Suicide Bunny

142110

I have two functions:

shell() uses getchar() to get user input

playLED() plays a LED animation

I have two tasks running in FreeRTOS

    xTaskCreate(

                    shell,

                    "shell",

                    512,

                    NULL,

                    1,

                    NULL);



    xTaskCreate(

                    playLED,

                    "playLED",

                    512,

                    NULL,

                    15,

                    NULL );

    vTaskStartScheduler();

Then I noticed the LED animation play become step-wise, it changes only when getchar() received input from user, instead of a smooth animation.

I've already set LED priority a lot higher, however this didn't fix the halt. Is there anything else that I should configure somewhere?

The code is run on NXP LPC54018 board with MCUXpresso. A similar problem on a different device can be found at https://os.mbed.com/questions/781/Skip-getchar-if-no-input-using-interrupt/

freertos

edited Oct 29 '18 at 18:02

asked Oct 27 '18 at 0:08

Suicide Bunny

142110

edited Oct 29 '18 at 18:02

asked Oct 27 '18 at 0:08

Suicide Bunny

142110

edited Oct 29 '18 at 18:02

asked Oct 27 '18 at 0:08

Suicide Bunny

142110

asked Oct 27 '18 at 0:08

Suicide Bunny

142110

asked Oct 27 '18 at 0:08

Suicide Bunny

142110

Can you better describe your environment (CPU, libraries, µC, toolset)? getchar() is not part of FreeRTOS. So only answers specific to your environment can be given.

– Codo
Oct 27 '18 at 9:17

Thanks for the reply. I am using it with a MCUxpresso on NXP LPC 54018

– Suicide Bunny
Oct 29 '18 at 17:59

add a comment |

Can you better describe your environment (CPU, libraries, µC, toolset)? getchar() is not part of FreeRTOS. So only answers specific to your environment can be given.

– Codo
Oct 27 '18 at 9:17

Thanks for the reply. I am using it with a MCUxpresso on NXP LPC 54018

– Suicide Bunny
Oct 29 '18 at 17:59

Can you better describe your environment (CPU, libraries, µC, toolset)? getchar() is not part of FreeRTOS. So only answers specific to your environment can be given.

– Codo
Oct 27 '18 at 9:17

Thanks for the reply. I am using it with a MCUxpresso on NXP LPC 54018

– Suicide Bunny
Oct 29 '18 at 17:59

add a comment |

2 Answers
2

active

oldest

votes

Does getchar() disable interrupts at all when receiving input? In that case the FreeRTOS scheduler will not be able to run the high priority task.

answered Oct 27 '18 at 7:04

stathisv

38614

Thanks for the reply. That's what I suspect but I don't know how to fix that. My expectation that the interrupt should be isolated to this task only but somehow it affect everything

– Suicide Bunny
Oct 29 '18 at 17:58

add a comment |

I think vTaskDelay(1) in the beginning of the task with getChar will resolve the problem.

Also you can change order of creation of tasks, it can also help.

answered Nov 22 '18 at 20:20

SG92

416

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

Does getchar() disable interrupts at all when receiving input? In that case the FreeRTOS scheduler will not be able to run the high priority task.

answered Oct 27 '18 at 7:04

stathisv

38614

Thanks for the reply. That's what I suspect but I don't know how to fix that. My expectation that the interrupt should be isolated to this task only but somehow it affect everything

– Suicide Bunny
Oct 29 '18 at 17:58

add a comment |

Does getchar() disable interrupts at all when receiving input? In that case the FreeRTOS scheduler will not be able to run the high priority task.

answered Oct 27 '18 at 7:04

stathisv

38614

Thanks for the reply. That's what I suspect but I don't know how to fix that. My expectation that the interrupt should be isolated to this task only but somehow it affect everything

– Suicide Bunny
Oct 29 '18 at 17:58

add a comment |

Does getchar() disable interrupts at all when receiving input? In that case the FreeRTOS scheduler will not be able to run the high priority task.

answered Oct 27 '18 at 7:04

stathisv

38614

Does getchar() disable interrupts at all when receiving input? In that case the FreeRTOS scheduler will not be able to run the high priority task.

answered Oct 27 '18 at 7:04

stathisv

38614

answered Oct 27 '18 at 7:04

stathisv

38614

answered Oct 27 '18 at 7:04

stathisv

38614

answered Oct 27 '18 at 7:04

stathisv

38614

Thanks for the reply. That's what I suspect but I don't know how to fix that. My expectation that the interrupt should be isolated to this task only but somehow it affect everything

– Suicide Bunny
Oct 29 '18 at 17:58

add a comment |

Thanks for the reply. That's what I suspect but I don't know how to fix that. My expectation that the interrupt should be isolated to this task only but somehow it affect everything

– Suicide Bunny
Oct 29 '18 at 17:58

Thanks for the reply. That's what I suspect but I don't know how to fix that. My expectation that the interrupt should be isolated to this task only but somehow it affect everything

– Suicide Bunny
Oct 29 '18 at 17:58

add a comment |

I think vTaskDelay(1) in the beginning of the task with getChar will resolve the problem.

Also you can change order of creation of tasks, it can also help.

answered Nov 22 '18 at 20:20

SG92

416

add a comment |

I think vTaskDelay(1) in the beginning of the task with getChar will resolve the problem.

Also you can change order of creation of tasks, it can also help.

answered Nov 22 '18 at 20:20

SG92

416

add a comment |

I think vTaskDelay(1) in the beginning of the task with getChar will resolve the problem.

Also you can change order of creation of tasks, it can also help.

answered Nov 22 '18 at 20:20

SG92

416

I think vTaskDelay(1) in the beginning of the task with getChar will resolve the problem.

Also you can change order of creation of tasks, it can also help.

answered Nov 22 '18 at 20:20

SG92

416

answered Nov 22 '18 at 20:20

SG92

416

answered Nov 22 '18 at 20:20

SG92

416

answered Nov 22 '18 at 20:20

SG92

416

add a comment |

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