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 mxfCanBusRxSamplingRead() or mxfCanBusRxSamplingSingleRead() functions.

The MXF_CANBUS_SAMPREC structure must be used for reading an CAN message with sampling service.

Example

canbus_sampling.c
The example below shows how to implement an CAN sampling receive application.

#define BUFFER_SIZE     4096 // 4KB

HMXF_SERVER server;
HMXF_CHANNEL rxChannel;
HMXF_BUFFER  rxBuffer;
MXF_CANBUS_SAMPREC *hostBuffer=NULL;
MXF_CANBUS_SAMPREC *recSamp;
uint64 ID=0x08120000;
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_CANBUS_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 ID
   if (!rc)
      rc = mxfA429RxSamplingMsgSelectSet(rxBuffer, MXF_MSG_DESELECT, 1, &ID);

    // 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)
   {
      recSamp = hostBuffer;
      rc = mxfCanBusRxSamplingRead(rxBuffer, 0, 0, BUFFER_SIZE, &msgsCount, &bytesCount, hostBuffer);
      for (j = 0; j < msgsCount && !rc; j++)
      {
         printf("   %03llu: Timetag=%012llu, Size=%u", j, recSamp->timeTag, recSamp->dataSize);
         if (!recSamp->control)
            printf(" OK");
         else
            printf(" Error");

         printf("\n        Data=");
         for (byte = 0; byte<recSamp->dataSize; byte++)
         {
            printf("%02X ", recSamp->data[byte]);
         }
         printf("\n");

         rc = mxfCanBusNextSamplingRecordPtrGet(recSamp, &recSamp);
      }
   }

   ...