CC2650: Handles in central mode

Hi Tom

Thank you for the answer!

Tom Kopriva said:

1st, you'd want to find the correct service (given a UUID). As soon you discovered a service, you are given a range (or location) of handles (svcStartHdl and svcEndHdl) that belong to that service. By definition, a service can have multiple characteristics. Within these handles, you are looking for a specific Characteristic Declaration given with a specific UUID.

I understood this part. Here is my GATT profile declaration:

  // Simple Profile Service
  {
    { ATT_BT_UUID_SIZE, primaryServiceUUID }, /* type */
    GATT_PERMIT_READ,                         /* permissions */
    0,                                        /* handle */
    (uint8 *)&simpleProfileService            /* pValue */
  },

    // Characteristic Test Declaration
    {
      { ATT_BT_UUID_SIZE, characterUUID },
      GATT_PERMIT_READ,
      0,
      &simpleProfileCharTestProps
    },

  // Characteristic Value Test
  {
    { ATT_BT_UUID_SIZE, simpleProfilecharTestUUID },
    GATT_PERMIT_READ,
    0,
    &simpleProfileCharTest
  },

  // Characteristic Test configuration
  {
    { ATT_BT_UUID_SIZE, clientCharCfgUUID },
    GATT_PERMIT_READ | GATT_PERMIT_WRITE,
    0,
    (uint8 *)&simpleProfileCharTestConfig
  },

  // Characteristic Test User Description
  {
    { ATT_BT_UUID_SIZE, charUserDescUUID },
    GATT_PERMIT_READ,
    0,
    simpleProfileCharTestUserDesp
  },

There is one service. What I'like to do is to enable notifications for the test value characteristics. To do so I need to write 0x0001 to the test configuration characteristic. So I need to get a handle to this (the second last characteristic in the above code block) characteristic.


Now about the second part of yur answer I am not sure wether I understood you correctly. Is the following procedure correct?

First use

req.startHandle = svcStartHdl;
req.endHandle = svcEndHdl;
req.type.len = ATT_BT_UUID_SIZE;
req.type.uuid[0] = LO_UINT16(SIMPLEPROFILE_CHARTEST_UUID);
req.type.uuid[1] = HI_UINT16(SIMPLEPROFILE_CHARTEST_UUID);
VOID GATT_ReadUsingCharUUID(connHandle, &req, selfEntity);

and

  else if (discState == BLE_DISC_STATE_CHAR)
  {
    // Characteristic found, store handle
    if ((pMsg->method == ATT_READ_BY_TYPE_RSP) && (pMsg->msg.readByTypeRsp.numPairs > 0))
    {
      charHdl = BUILD_UINT16(pMsg->msg.readByTypeRsp.pDataList[0], pMsg->msg.readByTypeRsp.pDataList[1]);
      
      LCD_WRITE_STRING_VALUE("charHdl:", charHdl, 10, LCD_PAGE6);

      LCD_WRITE_STRING("Simple Svc Found", LCD_PAGE2);
      procedureInProgress = FALSE;
    }
    
    discState = BLE_DISC_STATE_IDLE;
  }

to get a handle (charHdl). With this handle I can now read (and eventually write) to the characteristic test declaration (the fourth last characteristic in the above decaration). Correct?

But my goal is to write to the second last characteristic in the above declaration. So I need to read from the characteristic test declaration to get a handle to the "Characteristic Test configuration". How to do this? This is not done in the simpleBLECentral example.

I managed to solve the problem. The handle of the characteristic that I need to write to seems to be 40. How to discover this information is still not clear to me, but it works now and I get notifications.

Other question:
How should I design my application to sample at 20kHz 12 bit samples from the ADC and transmit over bluetooth? The sample is properly wroking (I used sensor controller studio to program the sensor controller). So I get alerts if the ring buffer contains 120 samples. Now my idea is that in the interrupt routine I copy these 120 samples to a buffer and add a message with a pointer to that bufferto the RTOS message queue. Then if the message is dequeued and processed, I write the 120 samples to a single characteristic value. This characteristic has notifications enabled.
Is this the standard approach for high data rates or should I proceed differently? Maybe using multiple characteristics (max 4) with notifications enabled. Can I call the function SimpleProfile_SetParameter(...) twice directly after eachother or will I loose data this way?