Telink TLSR8232 BLE SDK Developer Handbook
AN-19112700-E1 85 Ver.1.0.0
Users should balance on it. There are requirements for configurations of Tx FIFO and
Rx FIFO. Misconfigurations will lead to unexpected errors. The following provides the
configurations and examples.
If users want to set the maximum transmission data length to 251 Bytes, Tx FIFO
should be set as 251 + 12 = 263 Bytes, considering 4-byte alignment, Tx FIFO
should be set to 264 Bytes finally.
If users want to set the maximum receiving data length to 251 Bytes, Rx FIFO should
be set as 251 + 28 = 279 Bytes，considering 16-byte alignment, Tx FIFO should be
set to 288 Bytes finally.
Conclusion:
Tx FIFO size = actual maximum Payload size of transmission + 12 (4-byte aligned)
Rx FIFO size = actual maximum payload size of receiving + 28 (16-byte aligned)
3.3 L2CAP
Logical Link Control and Adaptation Protocol, L2CAP for short, connects the upper APP
layer and the lower Controller layer. By acting as an adaptor between the Host and the
Controller, the L2CAP makes data processing details of the Controller become negligible
to the upper-layer application operations.
The L2CAP layer of BLE is a simplified version of classical Bluetooth. In basic mode, it
does not implement segmentation and re-assembly, has no involvement of flow control
and re-transmission, and only uses fixed channels for communication.
The figure below shows simple L2CAP structure: Data of the APP layer are sent in
packets to the BLE Controller. The BLE Controller assembles the received data into
different CID data and report them to the Host layer.
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