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Using Events in FreeRTOS

Posted by sanchitgoel17 on May 17, 2016

Hi,

I'm porting my application that's written on ST10 micro-controller to STM32F407 using STCubeMX tool based on FreeRTOS in Keil IDE. I want to use 50 events in a particular task but FreeRTOS doesn't allow me to use more than 32 events that is based on bit field. So, any help on how to define/use more than 32 events would be highly appreciated.


Using Events in FreeRTOS

Posted by davedoors on May 17, 2016

Use 2 event groups instead of 1.


Using Events in FreeRTOS

Posted by sanchitgoel17 on May 17, 2016

Dave, how can I use 2 event groups for a single task? And I'm using CMSIS OS as wrapper on top of FreeRTOS. I would like to use osSignalSet() function that is provided by CMSIS OS.


Using Events in FreeRTOS

Posted by rtel on May 17, 2016

Use 2 event groups instead of 1.

...and allocate a bit in the first event group to indicate if a bit in the second event group is set or not - that way you only need to block on one not both.


Using Events in FreeRTOS

Posted by sanchitgoel17 on May 17, 2016

In CMSIS OS,

Can I have these options: 1. Instead of passing eSetBits as the 3rd argument to function xTaskNotify() I want to pass eSetValueWithoutOverwrite. 2. I want to change type of ulNotifiedValue from "volatile uint32_t" to "volatile long long" in case I pass the third parameter as eSetBits.

If you confirm this can be implemented, then I will request ST to fix this up in the CMSIS RTOS.


Using Events in FreeRTOS

Posted by rtel on May 17, 2016

I'm not familiar with the CMSIS OS API, so can't comment on that, but in FreeRTOS the notification value must be 32-bits.


Using Events in FreeRTOS

Posted by rajeevcrc on May 17, 2016

Hi,

I want to confirm following with respect to FreeRTOS 1. Can we use /call atomic instruction (available with ARM cortex M4 processor) and use it before manipulation ulNotifiedValue of type "long long" 2. If I go with current impelementation available with FreeRTOS, I believe, I can pass the 3rd argument to function xTaskNotify() as eSetValueWithoutOverwrite. However, I will have to check the return value to confirm whether the signal will be sent.

Rajeev


Using Events in FreeRTOS

Posted by rtel on May 17, 2016

I want to confirm following with respect to FreeRTOS 1. Can we use /call atomic instruction (available with ARM cortex M4 processor) and use it before manipulation ulNotifiedValue of type "long long"

I don't understand the question, but as per my reply a few moments ago, the notification value must be 32-bits.

  1. If I go with current impelementation available with FreeRTOS, I believe, I can pass the 3rd argument to function xTaskNotify() as eSetValueWithoutOverwrite. However, I will have to check the return value to confirm whether the sinal will be sent.

That is correct. http://www.freertos.org/xTaskNotify.html

Regards.


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