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Regarding Pairing issue in HOGP profile and FCS errors

Sunil Mankame
Intellectual 300 points
Other Parts Discussed in Thread: CC2541, CC2540

Hi,

I am using BLE 1.3.2 based software on my peripheral device based on TI CC2541 chip.

I have no problem in pairing with TI Advanced Remote dongle (HOGP)  basedon CC2540.

But, I am facing problem in pairing with dongle of another make.

The profile that I am working on is HID over GATT (HOGP).

I am getting lot of FCS errors in HOGP pairing in the Pacaket Sniffer Captures.

Are these FCS errors causing any issue in pairing with the Dongle of another make?

One out of four packets has FCS error

I dont doubt on the hardware, because I dont get any FCS errors when I check with other profile on the same board.

Any idea or clue can help me in further debugging.

Thanx in advance,

Sunil

 

  • 0
    Intellectual 300 points

    Hi E2E Community,

    I did few more experiments and following is the update.

    I am using another demo remote (peripheral device) based on some other chipset and it is able to pair and connect with the other dongle.

    I changed the AdvData of the TI CC2541 based remote to match that of the other remote which works with the dongle.

    I did not see any change in behaviour.

    I also changed the advertising interval to be same as in the other remote. But, no luck yet.

    Inspite of all these changes the TI CC2541 based remote still able to pair and work with TI Advanced Remote BLE-HOGP dongle.

    But I dont understand why it is not working with Dongle from other vendor.

    I observed one difference in the sniffer captures.

    The only diference is thatthe TI based remote's advertisements have lot of FCSerrors where as the other one has none.

    Could this be the reason for not being able to pair with the other dongle.

    As per my knowledge, the Target Dongle should ignore packets with FCSerrors and still continue to be in in initiating state and interpret the othet advt. packets. But I am not able to find any CONNECT_REQ or any other packets sent by the dongle under discussion.

    Can anyone share you knowledge if you had undergone similar experience?

    Thanks in advance,

    Sunil

  • 0 in reply to Sunil Mankame
    Intellectual 300 points

    Hi TI E2E Community,

    I have further update on the issue that I am facing.

    As the sniffer captures of advertisment from remote found to be OK, I guessed freq. synchronization could be a problem.

    So, I changed the number of preamble bytes to give more time for synchronization receiver end (i.e., Dongle). 

    I did it by changing the value PHY_PREAMBLE_SYNC defined in phy.h

    I increased it to all possible values but still no luck.

    I am thinking if the noise level of the packets received at Dongle side is too high, it may get ignored due to FCS errors.

    Is there a way to confirm that?

    I have started using an external SMA antenna on remote side but still no luck.

    Can anyone provide some suggestions?

    Regards,

    Sunil

  • 0 in reply to Sunil Mankame
    Intellectual 300 points

    Hi TI experts,

    I also configured HID_INITIAL_ADV_INT_MIN and HID_INITIAL_ADV_INT_MAX to the least possible value of 32 corresponding to 20ms (minimum advertising interval possible as per Bluetooth V4.0 spec).

    But still not able to pair with the dongle of the other vendor.

    Pleasenote that the other vendor dongle (HID mode) that I am using is nano type. It is small size. Is the receiver side (dongle) antenna causing the problem?

    The TI's dongle works fine. Does the size matter wrt Antenna reception?

    Regards,

    Sunil

  • 0 in reply to Sunil Mankame
    Intellectual 300 points

    Hi All,

     

    This issue is closed now.

    The root cause was the faulty hardware

    After tuning the crystal with proper capacitors, the issue is resolved.

     

    Regards,

    Sunil