Lab 108 (AI KIT): Bluetooth Low Energy Device Advertising

Background

Overview of the CYW43439 Bluetooth Core

The Infineon AIROC CYW43439 chipset (integrated inside the Murata Type 1YN module) provides Bluetooth v5.2 capabilities, supporting Basic Rate (BR), Enhanced Data Rate (EDR), and Bluetooth® Low Energy (BLE).

Step 1: Power Sequencing and Clock Requirements

Similar to the Wi-Fi section, the Bluetooth core relies on strict power sequencing and an external clock:

  1. Supply Power: The module requires a main battery voltage (VBAT, typically 3.6 V) and an IO supply voltage (VIO, typically 1.8 V or 3.3 V).
  2. Ramp and Timing: VBAT must ramp up (from 10% to 90%) no faster than 40 microseconds, and it must be powered up before or simultaneously with VIO.
  3. External Sleep Clock: The Bluetooth core requires a continuous 32.768 kHz external sleep clock applied to the LPO_IN pin for proper operation.

Step 2: Bluetooth Initialization and Reset

To initialize the Bluetooth section and bring it out of its reset state:

  1. Assert BT_REG_ON: Drive the BT_REG_ON pin high. On the PSoC 6 MCU, this is connected to pin P3.4.
  2. Asserting this pin powers up the internal regulators dedicated to the Bluetooth section. (Note: Deasserting this pin holds the Bluetooth section in reset. It features an internal 200 kΩ pull-down resistor by default).

Step 3: Configure the Communication Interfaces

Unlike the Wi-Fi core, which uses SDIO, the Bluetooth core relies on a UART interface for control and a PCM interface for audio:

  1. HCI UART Interface: Configure the PSoC 6 MCU to use a high-speed 4-wire UART interface. You must configure the following PSoC 6 pins:
    • BT_UART_TXD (Serial Output): PSoC 6 pin P3.[0].
    • BT_UART_RXD (Serial Input): PSoC 6 pin P3.[1].
    • BT_UART_CTS (Clear-to-Send): PSoC 6 pin P3.[2].
    • BT_UART_RTS (Request-to-Send): PSoC 6 pin P3.[3].
  2. PCM Audio Interface (Optional): If your application streams Bluetooth audio, you must also configure the PCM data pins (BT_PCM_CLK, BT_PCM_SYNC, BT_PCM_IN, BT_PCM_OUT), which can operate in either master or slave mode.

Step 4: Configure Bluetooth Wake Signals (Power Management)

To optimize power consumption during idle states, you must configure the dedicated wake-up GPIOs:

  1. Enable BT_HOST_WAKE: Configure PSoC 6 pin P4.[0] as an input. The Bluetooth module uses this signal to wake up the host PSoC 6 MCU when it receives incoming Bluetooth data.
  2. Enable BT_DEV_WAKE: Configure PSoC 6 pin P3.[5] as an output. The PSoC 6 MCU asserts this signal to wake up the Bluetooth device when the host needs to transmit data.

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