CCS/CC2564MODN: etGATT_Server_Device_Buffer_Empty not called

Pascale Meier

Part Number: CC2564MODN

Tool/software: Code Composer Studio

I'd like to write to a characteristic as in the SPPLE example (I took that example code and modified it for my own purposes) using the function call

Result = GATT_Write_Without_Response_Request(
BluetoothStackID, ConnectionID,
DeviceInfo_->ClientInfo.Rx_Characteristic,
(Word_t) DataCount,
&SPPLEBufferNotify[TransmitIndex]);

However, when I send too much data I get the return value: BTPS_ERROR_INSUFFICIENT_BUFFER_SPACE. So, I'm sending too many packets obviously. The Bluetopia documentation says that the user has to wait for the callback etGATT_Connection_Device_Buffer_Empty to be called before sending more data. So I expected to get this callback whenever the queue becomes empty but it seems like that this callback is never called, so the question is why? I also expect this callback if I don't have an overflow, if I send, let's say, just 50 bytes, but this is not the case.

First, I did everything in the etGATT_Server_Write_Request callback. But then I thought that the etGATT_Connection_Device_Buffer_Empty callback will probably be missed if I stick there so I just set a flag to execute the sending process in the main file where a scheduler is set up. However, etGATT_Connection_Device_Buffer_Empty was called neither. Also, as soon as the error BTPS_ERROR_INSUFFICIENT_BUFFER_SPACE triggers, it keeps returning that error, so that I have to restart the device, why does it get stuck there?

Thanks in advance

Pascale

over 7 years ago

0 Vihang Parmar over 7 years ago

TI__Mastermind 29250 points

Hi Pascale,

If you refer to the SPPLEDemo, the etGATT_Connection_Device_Buffer_Empty event is under the GATT_Connection_Event_Callback and not the GATT_ServerEventCallback.

BR,
Vihang

0 Pascale Meier over 7 years ago

Prodigy 60 points

Ok, my bad. Yeah the device is acting as server, so calling

Result = GATT_Handle_Value_Notification(
BluetoothStackID, SPPLEServiceID, ConnectionID,
SPPLE_RX_AND_TX_CHARACTERISTIC_ATTRIBUTE_OFFSET,
(Word_t) DataCount,
&SPPLEBufferNotify[TransmitIndex]);

which should call etGATT_Server_Device_Buffer_Empty() in GATT_ServerEventCallback(). But this isn't happening. So I'mstill having the same problem as described beforehand.

Thanks

0 Vihang Parmar over 7 years ago in reply to Pascale Meier

TI__Mastermind 29250 points

Hi Pascale,

I do see the etGATT_Connection_Device_Buffer_Empty event popping up for the GATT_Handle_Value_Notification() API in the default SPPLEDemo. Have you made any major changes to this part of the demo?

Best regards,
Vihang

0 Pascale Meier over 7 years ago in reply to Vihang Parmar

Prodigy 60 points

Thanks for your reply. Actually, I went back to a just slightly changed version of the original one (other pinout). However, I expect etGATT_Server_Device_Buffer_Empty to be called, not etGATT_Connection_Device_Buffer_Empty. In my setup, the device is acting as a server whil the tablet (running LightBlue) is running as a client. So I do the steps as described in the SPPLEDemo-Wiki.

SPP+LE>Server

SPP+LE>RegisterSPPLE 
Sucessfully registered SPPLE Service. 

SPP+LE>AdvertiseLE 1 
GAP_LE_Advertising_Enable success.

Afterwards, I enable listen to notifications on the TX and RX Credits Characteristic and do the following as in the description:

Open the Tx Credits Characteristic (0xBA04C4B2-892B-43BE-B69C-5D13F2195392).
Choose "Write new value".
Type 6400. (100 credits = 0x0064 little-endian)
Choose Done.
Press the back button in the top left corner

Then I enter into the console:

SPP+LE>LESend 5cfc3252180b 100

Send Complete, Sent 100.

GATT_Set_Queuing_Parameters(BluetoothStackID, (unsigned int)NumberLEPackets, (unsigned int)(NumberLEPackets-1), FALSE); has

NumberLEPackets set to 7, and I added a Display call to detect the callback after GATT_Handle_Value_Notification() is going to be called.

static void BTPSAPI GATT_ServerEventCallback(unsigned int BluetoothStackID, GATT_Server_Event_Data_t *GATT_ServerEventData, unsigned long CallbackParameter)
{
int LEConnectionIndex;
Byte_t Temp[2];
Word_t Value;
Word_t PreviousValue;
Word_t AttributeOffset;
DeviceInfo_t *DeviceInfo;

/* Verify that all parameters to this callback are Semi-Valid. */
if((BluetoothStackID) && (GATT_ServerEventData))
{
switch(GATT_ServerEventData->Event_Data_Type)
{
case etGATT_Server_Device_Buffer_Empty:
Display(("etGATT_Server_Device_Buffer_Empty\r\n"));
break;
case etGATT_Server_Read_Request:
/* Verify that the Event Data is valid. */
if(GATT_ServerEventData->Event_Data.GATT_Read_Request_Data)
{

I'm also tracking the etGATT_Connection_Device_Buffer_Empty callback, which isn't called either.

Any ideas?

Thanks,

Pascale

0 Pascale Meier over 7 years ago in reply to Pascale Meier

Prodigy 60 points

Ok, I realized that tha callback is called only if an buffer overflow exists.

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CCS/CC2564MODN: etGATT_Server_Device_Buffer_Empty not called