WICED Bluetooth Host Stack solution (for FreeRTOS)

Overview

WICED Bluetooth host stack solution includes bluetooth stack library, bluetooth controller firmware and platform/os porting layer. Bluetooth stack library is designed for embedded device, it consumes less RAM/ROM usage but still keeps high performance. With WICED Bluetooth API set, application developers can use them easily to create their own application. The porting layer is implemented by CYHAL and CY_RTOS_AL (Hardware/Operation System Adaptation Layer), hence it can adapt to Cypress platforms, and easy to port to other vendor's platform.

Platform HCI transport config

Besides of stack settings, HCI configuration is also required to specify, including pins, format and UART baudrate. Please refer to cybt_platform_config.h for more detail:

• structure cybt_platform_config_t
• API cybt_platform_config_init( )

The API cybt_platform_config_init( ) shall be invoked prior to wiced_bt_stack_init( )

How to enable trace log?

• Compile time definition: Please refer to cybt_platform_config.h which can set individual trace log (Default set all category is CYBT_TRACE_LEVEL_ERROR)
• Run time update: Dynamic set trace level by using API cybt_platform_set_trace_level( )
• Enable libbtstack.a trace or use WICED_BT_TRACE macro, please set CYBT_TRACE_ID_STACK category which be invoked prior to host_stack_platform_interface_init( ), and can not used after host_stack_platform_interface_deinit( )
• Undefined CYBT_PLATFORM_TRACE_ENABLE to disables all the debug log messages

//#define CYBT_PLATFORM_TRACE_ENABLE

Working flow

~ release-v1.3.0

• Porting layer create 2 tasks
  • HCI task which handles HCI packet transmission and reception
  • BTU/BT task which handles Bluetooth core stack and profiles
• TX path:
  • BT stack calls pf_write_xxx_to_lower( ) with packet data
  • Inside those functions,
    • Allocate memory from porting layer heap for the TX packet
    • Put TX packet into HCI task queue
  • HCI task gets TX packet from the queue then write the same to HCI UART
• RX path:
  • UART driver fires the interrupt when data was coming from BT controller
  • In IRQ handler, put the related message to HCI task queue
  • Once HCI task gets the message,
    • Allocate memory from porting layer heap, read the packet from UART and write the same to the allocated memory
    • Put RX packet into BT task queue.
  • BT task gets RX packet then calls wiced_bt_process_xxx() to notify BT stack

since release-v2.0.0

• Porting layer create 2 tasks
  • HCI_TX task which handles HCI packet from BT stack to BT controller
  • HCI_RX task which handles HCI packet from BT controller to BT stack
• TX path:
  • BT stack calls pf_write_xxx_to_lower( ) with packet data
  • Inside those functions,
    • Allocate memory from porting layer heap for the TX packet
    • Put TX packet into HCI_TX task queue
  • HCI_TX task gets TX packet from the queue then write the same to HCI UART
• RX path:
  • UART driver fires the interrupt when data was coming from BT controller
  • In IRQ handler, put the related message to HCI_RX task queue
  • Once HCI_RX task gets the message,
    • Read the packet from UART and write the same to the static buffer
    • Call wiced_bt_process_xxx() to notify BT stack

API Reference Manual

• Bluetooth platform API manual
• Bluetooth stack BLE API manual

© Cypress Semiconductor Corporation, 2020.