Receive random data after connect

[sonnyz]

Hi,

I'm using 51822 QFAC SDK11 S130. The 51822 will receive a group of 18 bytes data from the phone. I'm facing a strange issue: every time after the BLE is connected, I will first receive a 18 bytes data which was not sent from the phone. This group of data basically has fixed values, but nothing to do with any data sent from the phone. I have no idea where are they coming from, can anyone give me a clue? Thank a lot!

Sonny

[awneil]

https://www.argenox.com/library/bluetooth-low-energy/ultimate-guide-to-debugging-bluetooth-smart-ble-products/

How are you sending the data ?

What debugging have you done to see what's going on?

Have you checked for uninitialised variables?

[sonnyz]

Thank you Awneil!

I use this to receive data from the phone: 

case BLE_GATTS_EVT_WRITE:     //receive data from the phone
{
    uint8_t * p_data = p_ble_evt->evt.gatts_evt.params.write.data;
    //printf("received data: %d  %d...", p_data[0], p_data[1] ....);  //18 data
}

 It shouldn't have uninitialized variables issue. From the debug, I can see that the first data packet (18 data) is always something else then what I have sent from the phone, the real data start from the 2nd packet. 

[awneil]

Are you sure that write is to  your Service/Characteristic ?

Check p_ble_evt->evt.gatts_evt.params.write.uuid

[sonnyz]

Thank you awneil! Just got time to test with your suggestion, but it shows incompatible error. Never mind, I just filter out the random value, everything else is fine. 

[awneil]

sonnyz said:

it shows incompatible error

not sure what you mean by that?

sonnyz said:

I just filter out the random value, everything else is fine

OK - jolly good