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Questions regarding interrupts level in nRF52840 chip

Chaabane

Hello,

I'm integrating mesh and freeRTOS and having problems with interrupts priorities on both sides. It's a little bit confusing to set the interrupt priority on each side so I'm trying to understand how the mesh interrupts are set and handled  thus the below questions :

1 - The number of bits used to define priority in the chip are set to 3  (__NVIC_PRIO_BITS), this means that an interrupt can have a priority from 0 to 7! assuming sub-priority is not using since I couldn't fin any information about it in the datasheet, is that correct ?

2- I read in the forum that the mesh application thread can be set to NRF_MESH_IRQ_PRIORITY_LOWEST(7) or NRF_MESH_IRQ_PRIORITY_THREAD(15). What's the relation between these values and the hardware interrupt priorities in the first question ?

Thank you

  • +1

    Hi,

     

    1 - The number of bits used to define priority in the chip are set to 3  (__NVIC_PRIO_BITS), this means that an interrupt can have a priority from 0 to 7! assuming sub-priority is not using since I couldn't fin any information about it in the datasheet, is that correct ?

    This corresponds to the NVIC interrupt priorities available in the hardware core of the Cortex M4 CPU, which are from 0 (highest priority) to 7 (lowest priority). Information related to the CPU core can be found on ARMs infocenter: http://infocenter.arm.com/help/topic/com.arm.doc.100166_0001_00_en/index.html

     

    2- I read in the forum that the mesh application thread can be set to NRF_MESH_IRQ_PRIORITY_LOWEST(7) or NRF_MESH_IRQ_PRIORITY_THREAD(15). What's the relation between these values and the hardware interrupt priorities in the first question ?

    The difference between the two is that NRF_MES_IRQ_PRIORITY_LOWEST is running in interrupt context, with priority level 7. This means that it will interrupt a function running in main-context (ie: your main while loop), but not any other interrupt priorities (from 6 to 0).

    NRF_MESH_IRQ_PRIORITY_THREAD is the same as running a function in your main-loop (thread and main is the same).

     

    Kind regards,

    Håkon

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