4 Replies Latest reply on Jun 21, 2018 11:23 AM by e.pratt_1639216

    Can't get GATT write "command complete" to send


      Hi All,


      I've gone through the forums, youtube videos, and the 100 days of PSOC samples to figure this out, and am stuck.  I can't get the "command complete" event to send from my peripheral back to central, and don't know why.  I handle CYBLE_EVT_GATTS_WRITE_REQ, update the GATT DB, and call CyBle_GattsWriteRsp -- but the command complete event never gets sent.  I've tried variations in the order, changing the gatt parameters, adding in additional calls to CyBle_ProcessEvents, or even putting in random delays -- yet it never works.  I attached a debugger to the Cypress sample code, and literally looked at each call linearly, and made the same calls on my own -- yet the response is still not sent.


      Here's the code link to an example program I made up to show what I expect to work:



      Line 100 is where I handle the Write Request.  Any ideas on why this doesn't send back the response I expect would be welcome.  The repo should clone and build on the BLE Pioneer kit.



        • 1. Re: Can't get GATT write "command complete" to send

          The documentation with the CyBle GattC Write command lists all of the events and response generated by it, as well as a quick summary of how they are handled. (You can see this by opening the API documentation for the BLE component, or doing a search-all for the function name).

          Also, the CYBLE_EVT_GATTS_WRITE_REQ event should have documentation associated with it in the same way as I mentioned above about what parameters and values are needed/handled/should be replied.

          • 2. Re: Can't get GATT write "command complete" to send

            I've already read the docs before asking.  The sample code I linked shows what should work according to everything in the docs and the Google.


            Here's the code snippet I expect to work:

               case CYBLE_EVT_GATTS_WRITE_REQ:
               // Get the write request event parameters
              wrReqParam = (CYBLE_GATTS_WRITE_REQ_PARAM_T*) eventParam;
               // see if the host wanted to write a new should blink flag
               if ( wrReqParam->handleValPair.attrHandle == CYBLE_LEDSTATE_ISBLINKING_CHAR_HANDLE )
              g_shouldBlink = wrReqParam->handleValPair.value.val[0];
               CyBle_GattsWriteRsp(g_bleConnectionHandle); // Send a response.


            Attaching the debugger shows the Ble Handler getting called.  The LED updates correctly based on what's written by Cysmart.  The GATTDB state is correct, as I can read the db later. But CySmart times out on the write request with this code -- yet works correctly with the PSoC 100 days code sample, "Day003_Custom_Profile_CapSense_RGB_LED".  I'm making the same calls in the same order as the sample.  It should just work.

            • 3. Re: Can't get GATT write "command complete" to send

              Aha!  I figured out the error.  It was something stupid.


              I can't call CyBle_GattsWriteRsp with my own generated handle.  I have to use the BLE generated handle!  The correct code must read:



              It works now!! Yay!

              • 4. Re: Can't get GATT write "command complete" to send

                Yeah, unless you have a need not to use the cypress variables, it is easier with only one possible BLE connection to leave all of the data/variables directly referenced.


                Glad you found the problem though