The customer needed to support two independent Bluetooth solutions on the same device, each capable of handling HFP (Hands-Free Profile) calls. Typically, this requires:

Hardware

Two separate PCM hardware interfaces.

Routing

Dedicated routing for each Bluetooth subsystem

Power

Increased PCB complexity, hardware BOM cost, and power usage.

However, the device hardware architecture only included one PCM interface, making it impossible to support dual-Bluetooth calling using traditional designs.

This created a major limitation:

➡️ Only one Bluetooth module could handle voice calls at a time unless additional hardware was added

We implemented an advanced PCM (Pulse Code Modulation) sharing mechanism that allows two independent Bluetooth subsystems (Bluetooth 1 and Bluetooth 2) to use a single PCM hardware interface to handle HFP (Hands-Free Profile) calls, without requiring additional hardware.

This solution enables seamless call audio routing for incoming and outgoing calls from either Bluetooth module while maintaining stability, timing accuracy, and resource control.

Key Benefits Delivered to the Client

• Eliminated need for a second PCM hardware block
• Reduced hardware cost and PCB redesign effort
• Enabled both Bluetooth modules to handle HFP calls reliably
• Ensured conflict-free call audio routing using intelligent slot checks
• Optimized power usage through smart PCM clock control
• Provided a scalable solution supporting up to four independent HFP calls with each Bluetooth can make two calls.