CSR8811 I2S/PCM data

[Aleksandr Mikoff]

Hello.

Let's imagine that I have the following setup: the bluetooth module CSR8811 is connected to the headset. 

After discovery/connect procedure the headset streams audio data and I wish to get the PCM/I2S data from CSR8811 chip using the I2S bus. 

Is it possible to do this in current version of BlueKitchen? If not, do I have any other options to stream audio data from the chip?

Thanks a lot.

[Matthias Ringwald]

Hi Aleksandr

Most Bluetooth chipsets that are connected via UART (H4/H5) will have SCO audio from HSP/HFP routed to the I2S bus interface by default.

if you don't set the ENABLE_SCO_OVER_HCI compile flag in btstack_config.h, the audio should end up there.

Please note that wide band speech in HFP needs to go through an mSBC codec. We're currently implementing this as part of BTstack, but

the SCO data then needs to be routed to the MCU instead of the Bluetooth's I2S interface. Some vendors come up with solutions for this,

e.g., the TI CC256x chipsets support "Assisted HFP" where the codec is implemented in the Bluetooth controller, although that disables the BLE support.

CSR has different chipsets and I think some have some kind of DSP for that, but I'm not sure about this.

Best

 Matthias

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[Aleksandr Mikoff]

Thank you so much for you reply. I am not interested in HFP, only the HSP is an aim of interest.

Only one question left - is it possible to send some type of codec config command to configure the I2S bus for CSR8811 in BlueKitchen (the same as it done in TI CC256x)?

среда, 27 июля 2016 г., 0:36:07 UTC+3 пользователь Aleksandr Mikoff написал:

[Matthias Ringwald]

Hi again

Yes, BTstack can send custom configuration commands to CSR chips. This happens with the commands here: https://github.com/bluekitchen/btstack/blob/master/chipset/csr/btstack_chipset_csr.c#L67

However, you'd need to figure out these commands as there's no public documentation on them. The best approach is to dig through the BlueZ sources and/or just Google for it. 

CSR chips have something like a key/value store and the used term is "PSKey". 

If that doesn't work, you could switch to the CC256x based Bluetooth modules that provide public documentation and also support via their E2E Forum.

Good luck

 Matthias