RTOS/CC2640: Unknown packet being sent using GATT_NOTIFY

sandeep mittal

Intellectual 525 points

Part Number: CC2640

Tool/software: TI-RTOS

Hi,

I'm using SimpleBlePeripheral example to develop my application. I'm using the function

SimpleProfile_SetParameter(SIMPLEPROFILE_CHAR4, SIMPLEPROFILE_CHAR4_LEN, TX_Buff16);

to send data over BLE.

However, when I see the packets on BTool, I see a data packet which is sent between every expected data packet. Below is the packet that is Unexpected, but received by the host on BTool:

[513] : <Rx> - 09:12:28.226
-Type : 0x04 (Event)
-EventCode : 0x00FF (HCI_LE_ExtEvent)
-Data Length : 0x1C (28) bytes(s)
Event : 0x051B (1307) (ATT_HandleValueNotification)
Status : 0x00 (0) (Success)
ConnHandle : 0x0000 (0)
PduLen : 0x16 (22)
Handle : 0x0027 (39)
Value : 48:3F:00:20:D9:7E:00:00:01:CA:01:10:01:CA:01:10:
01:CA:01:10

The value of this unexpected packet doesn't change. It;s the same packet which is received after every expected packet is received.

Can someone help me understand what is this packet?, why is it being sent?

Thanks,

Sandeep

over 9 years ago

0 sandeep mittal over 9 years ago

Intellectual 525 points

Isn't there anyone here to help me with this????

0 Marie H over 9 years ago in reply to sandeep mittal

TI__Guru* 83901 points

Hi Sandeep,

A handle value notification is used to notify the client that a characteristic value has changed. (See BLuetooth Core Spec chapter 4.10 CHARACTERISTIC VALUE NOTIFICATION.)

If you look at the attribute table of SIMPLEPROFILE_CHAR4, you will see that this characteristic has the notify property.

0 sandeep mittal over 9 years ago in reply to Marie H

Intellectual 525 points

Hi Marie,

So, does it mean that Notification characteristic can not be used for sending data ? I'm trying to send continuous stream of data over BLE. which characteristic is ideal for this purpose?

Thanks,

Sandeep

0 Marie H over 9 years ago in reply to sandeep mittal

TI__Guru* 83901 points

Hi Sandeep,

The notification property is typically used for characteristics you don't want to read often. E.g. a doorbell can give a notification every time it is pressed.

You can still use it but it doesn't make much sense. You can change the property of the characheristic, or use a different one. Or, even better, use Bluetooth Developer Studio to make a Profile that suits your needs. We have a SimpleLink Academy training for BDS here: dev.ti.com/.../

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RTOS/CC2640: Unknown packet being sent using GATT_NOTIFY