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SCO WB content over HCI UART

franck FLETER
Intellectual 400 points

Hi,

We are using TI BT CC256x chipset in our product, the HCI UART is used for  audio :

   A2DP - SBC

   A2DP - AAC

   SCO - WideBand speech

   RFCOMM/SPP for file transfer

On UART is clocked at 2.4 Mhz. The host processor is STM32F4, we did a very long run of SPP (with user data CRC) to check the integrity of our UART link.

Regarding the SCO configuration, we configure  HCI_VS_Write_SCO_Configuration (0xFE10) with the value 0x00, to reject packets with bad CRC.

With this current configuration, we can observe that we have sometimes burst of "WBS speech data" (60 bytes starting from the H2 header) full of 0x00 whereas the HCI header (first 4 bytes is correct).

The sniffer trace BPA600 shows that all the SCO WB packets are correct.

FYI, over the UART, our third-party BT stack (binary), reads 1 bytes, then 3 bytes, then bytes of "WBS speech" 

Any idea of this issue ?

Br,

  Franck

  • 0
    TI__Guru* 85400 points
    Hi Franck,

    Can you please retry after adding:
    Send_HCI_Write_SCO_Flow_Control_Enable 1

    Opcode: 0x0c2f

    Regards,
    Gigi Joseph.
  • 0 in reply to Joseph Gigi
    Intellectual 400 points

    H Joseph,

    Thanks for your feedback 

    SCO_Flow_Control is already set to 1. I should have mentioned this in my previous update.

    Any other idea / suggestion ?

    Br,

      Franck

  • 0 in reply to franck FLETER
    TI__Intellectual 2360 points

    Franck,

    Please check your usage of the HCI_VS_Write_SCO_Configuration() command. Note that the "TX buffer max latency" parameter is 2 bytes, which is different than the other 3 parameters.

    Also, within the HCI header of a SCO data packet please check the packet status flags bits when the error occurs. There are 4 possible values:

    0x00 = correctly received data
    0x01 = possibly invalid data
    0x10 = no data received
    0x11 = data partially lost

    Refer to the 4.0 spec in section "5.4.3 HCI Synchronous Data Packets" for more information on these values.

    Thanks,
    Samuel

  • 0 in reply to Samuel
    Intellectual 400 points
    Hi Samuel,

    I am so sorry to not replying to your suggestion earlier. I was so busy on other BT topics. I should apply your recommendations soon and let you know.
    BTW, I am going to open another ticket of BT issue, more critical for us, and saw with this TI chipset.

    Br,
    Franck