• Locked Locked
  • Replies 4 replies
  • Subscribers 51 subscribers
  • Views 795 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

How to change values from ATT_Handle_Value_Notify?

Alin Vasile
Prodigy 80 points


Hello!

I followed the TI link to optimize the BLE Throughput : http://processors.wiki.ti.com/index.php/CC2640_BLE_Throughput

I obtained a characteristic with 60 bytes but when I try to change the transmitted values it looks like in the screenshot.

I created a for loop to put values from 0 to 59 in the characteristic but it  send in ATT_Handle_Value_Notify from 0 to 0x13, on the first payload from 0x14 to 0x2E and in the final payload from 0x2F to 0x3B. How can I change the characteristic to write all values in ATT_Handle_Value_Notify, not in payload?

P.S. In ATT_Handle_Value_Notify the rest of the values are random.

Thanks,

Alin

  • TI__Mastermind 25035 points
    Hi Alin,

    It is not possible to send more than 20 bytes of data payload for notification as defined by the specification.

    Best wishes
  • in reply to Zahid Haq
    Prodigy 80 points
    Hi Zahid,

    So, you are saying that the ATT_Handle_Value_Notify is useless to be bigger? In this characteristic I have 60 bytes but I can't change values, it sends first 20 bytes with the data that I want and the rest of them are random bytes.
  • Prodigy 80 points

    I'm back with another question.

    I set the ATT_Handle_Value_Notify at 20 bytes and I want to transmit 8 packets in a 7.5 ms connection interval. I want to obtain something like

    1000 ms / 7.5 ms * 20 bytes * 8packets = 21333 bytes/sec = 170,666 bps. At this moment I am sending 5 packets which means 1000 ms / 7.5ms * 20bytes *5 packets = 13333bytes/sec = 106,666 bps.

    Here is a screenshot:

    As you can see the L2CAP Header is sent everytime with my data. Can I send the L2CAP Header only once in a connection interval?

    Now I am using a CC2650EM and a USB Dongle BLED112 from Bluegiga.

    Thank you!

  • in reply to Alin Vasile
    TI__Mastermind 25035 points
    Hi Alin,

    You can use a higher MAX_PDU_SIZE in your application(default is 27), and if both the peripheral and central side supports it, you should see L2CAP Header once for each notification.

    Best wishes