FreeRTOS队列结构C

Question

I do not understand how to declare a structure that I can use to send data between two threads in FreeRTOS.

I have two threads, the one should populate the struct with data, and the other one should read the data from the struct, which was sent with a message queue.

The data can be copied or via pointer, it is not large amounts of data.

In my main.c file I declare the structure and declare the queue and the queue handle: Before int main(void):

xQueueHandle LED_Queue_Handle, ChannelFreqQueue;

    struct AMessage
{
        uint8_t channelID;
        float channelFreq;
};

In main I create the queue

ChannelFreqQueue = xQueueCreate(2, sizeof(struct AMessage *));

In the task that needs to send data to the queue:

static void StopCompThread(void const *argument)
{
    uint32_t count=0;
    uint8_t ActiveChannel =0;
    uint16_t uartcount =0;
    const float period = 0.0085;
    static float frequency = 0;

    for (;;)
  {
        struct AMessage txIdrisData;

        if(xSemaphoreTake(OscStopSem, portMAX_DELAY))       // Timer 17 Callback 8.5ms
        {
                    HAL_TIM_Base_Stop_IT(&htim17);
                    __HAL_TIM_SET_COUNTER(&htim17,0);       
                    count = __HAL_TIM_GetCounter(&htim3);
                    uartcount++;


                            uint16_t pinstatus = (uint16_t)GPIOB->ODR & 0x2000;
                            if (pinstatus == 0)
                            {
                                ActiveChannel = 0x01;
                            }
                            else ActiveChannel = 0x02;

                            if (uartcount == 525)
                            {
                                txIdrisData.channelID = ActiveChannel;
                                txIdrisData.channelFreq = frequency;

                                xQueueSend(ChannelFreqQueue, (void *) &txIdrisData,portMAX_DELAY); 

                            }

        }

    } //FORever

} // StopCompThread

And then the task that needs to receive the data from the queue:

static void IDRISThread(void const *argument)
    {
        struct AMessage rxIdrisData;    

        float temp = 0.0;
        uint8_t channel = 0;
        char IdrisDataBuf[11] = {0}; // 3 Bytes x 4 channels = 12 Bytes
        uint8_t IdrisStatusByte = 0;

        for (;;)
      {
          xQueueReceive( ChannelFreqQueue, &( rxIdrisData ), portMAX_DELAY );

            temp = rxIdrisData.channelFreq;
            channel = rxIdrisData.channelID;

            temp = temp * 1000;

            snprintf(IdrisDataBuf, 2, "%.0f",temp); // Channel Data - Counts/Frequency

            if (channel == 0x00)
            {
                IdrisDataBuf[2] = 0x00;
            }
            if (channel == 0x01)
            {
                IdrisDataBuf[2] = 0x01;
            }

            uart_send(IdrisDataBuf, 12);


        } //FORever

    } // IDRISThread

I am sure that I have a misunderstanding of how to declare and use the structure and also that I have pointers and non-pointers mixed up. I have tried to use this API doc as reference: http://www.freertos.org/a00118.html

If someone can point out my mistakes or help with pseudo-code that might help me understand it would be appreciated.

Answer 1

You have no room to store elements in your queue

ChannelFreqQueue = xQueueCreate(2, sizeof(struct AMessage *));

Creates 2 pointer element to struct AMessage structures. What you need is 2 element array of struct AMessage

ChannelFreqQueue = xQueueCreate(2, sizeof(struct AMessage));

Answer 2

Why not just queue the structure, rather than a pointer to the structure, it would be much simpler. Read the blurb on the FreeRTOS Queues documentation page and see the "Alternatives To Using Queue Sets" section half way down the Queue Sets page.