Basic Sampling

The way to set a basic sampling receive application is as follows:

• A receive channel must be obtained using the mxfModuleChannelGet() or mxfModuleChannelAllGet() functions using MXF_SCLASS_RXSAMPLING_SRV subclass.
• The Sampling buffer must be allocated using the mxfRxSamplingBufferAlloc() function.
• A sampling kill time can be set with the mxfRxSamplingKilltimeSet() function to allow the invalidation of the last reception if the data is too old.
• Start the sampling using the mxfRxSamplingStart() function.
• Sampling read can be performed by using the mxfA429RxSamplingRead() or mxfA429RxSamplingSingleRead() functions and the data received decoded using the mxfA429ArwDecompose() function.

The MXF_A429_SAMPREC structure must be used for reading an ARINC 429 message with sampling service.

Example

ar429_rx_sampling.c
The example below shows how to implement an ARINC 429 sampling receive application.

#define BUFFER_SIZE     4096 // 4KB
#define LABEL           3

HMXF_SERVER server;
HMXF_CHANNEL rxChannel;
HMXF_BUFFER  rxBuffer;
MXF_A429_SAMPREC *hostBuffer=NULL;
MXF_A429_SAMPREC *recSamp;
uint32 label=LABEL, sdi, data, ssm, parity;
uint64 msgsCount, bytesCount;
uint64 j;
uint32 rc;

   ...

   // Sets timebase to 64-bit microseconds
   if (!rc)
      rc = mxfSystemTimeBaseSet(server, MXF_TIMEBASE_DEVICE_USEC);

   // Allocates host buffer
   if(!rc)
   {
      hostBuffer = (MXF_A429_SAMPREC *)malloc(BUFFER_SIZE);
      if(!hostBuffer)
         rc = MAXT_ERROR_MEM;
   }

   // Allocates RX sampling buffer
   if(!rc)
      rc = mxfRxSamplingBufferAlloc(rxChannel, BUFFER_SIZE, &rxBuffer, NULL);

   // Filters out a specific label
   if (!rc)
      rc = mxfA429RxSamplingMsgSelectSet(rxBuffer, MXF_MSG_DESELECT, 1, &label);

    // Sets sampling kill time to 1 second.
    if (!rc)
        rc = mxfRxSamplingKilltimeSet(rxBuffer, 1000000);      

   // Starts sampling
   if(!rc)
      rc = mxfRxSamplingStart(rxBuffer);

   ...

   // Reads and displays records
   if(!rc)
   {
      rc = mxfA429RxSamplingRead(rxBuffer, MXF_RXSAMPLING_FLAG_DEFAULT, 0, BUFFER_SIZE, &msgsCount, &bytesCount, hostBuffer);
      if(!rc)
      {
         printf("Read %llu messages\n\r", msgsCount);
         recSamp = (MXF_A429_SAMPREC*)hostBuffer;
         for (j=0; !rc && j<msgsCount; j++)
         {
            rc = mxfA429ArwDecompose(recSamp->data, &label, &sdi, &data, &ssm, &parity);
            if(!rc)
            {
               printf("%02llu: Timetag %llu - ARINC word=[%03llo,%lld,%05llX,%lld,%s]\n",
                      j, recSamp->timeTag, label, sdi, data, ssm, (parity==VMXF_A429_PARITY_ODD)?"ODD":"EVEN");
               if(!rc)
                  rc = mxfA429NextSamplingRecordPtrGet(recSamp, &recSamp);
            }
         }
      }
   }

   ...