ESP32-U4WDH Bluetooth Audio Framework on Espressif IDE

Job Specification: ESP32-U4WDH Bluetooth Audio Framework ### Job Title Embedded Engineer: ESP32-U4WDH Bluetooth Audio Framework (ESP-IDF 5.5+, ESP-ADF 2.8+, A2DP/HFP, MP3 & Auto-Reconnect) --- ### Project Overview We are seeking an experienced embedded firmware engineer to develop a clean, modular Bluetooth audio framework on an ESP32-U4WDH chip using Espressif's native tools. Espressif IDE (minimum version 4.3.0) shall be used. CRITICAL NOTE: This project is for a foundational framework, NOT a finished production application. We will be adding our own custom application logic, features, and code on top of this framework. The codebase must be highly structured, modular, and well-documented. --- ### Development Environment & Deliverables - Software Versions: Must use ESP-IDF version 5.5.4 (minimum) and ESP-ADF version 2.8 (minimum). - Target IDE: The finished framework must be delivered as a complete project that can be directly imported into the Espressif IDE environment (version 4.3.0 minimum). All necessary configuration files, components, and project files must be present so it compiles out-of-the-box. - Hardware Platform: Development can be done on any board containing the ESP32-U4WDH. We suggest using the ESP32 DevKit Mini. - Hardware Verification: To verify that the framework actually works, it is expected that you connect your development board with a real codec hardware setup. We strictly operate on a 'No audio - is no pay' basis. - Code Integration: The project may utilize and build upon multiple official examples provided by Espressif (such as combining the `pipeline_a2dp_sink_and_hfp` example with mixer/mp3 player examples). However, the final deliverable must be fully integrated into a single, cohesive framework that fulfills all requirements simultaneously. We will not accept disjointed or separate code examples. --- ### Fixed Architecture Constraints 1. Single Chip Architecture: Only the single ESP32-U4WDH package is used. There is no external RAM or ROM beyond what is integrated inside the U4WDH package. Memory footprint optimization is critical. 2. Codec Support: The system uses the TLV320AIC3204 codec. Note: We will provide the initialization code and all driver code for this specific device. You do not need to write the codec driver. 3. Pin Configuration: All I2S and I2C pins will be configured and mapped by us. --- ### Core Framework Functionality & Deliverables 4. Bluetooth Connection & Auto-Reconnect: - Implement simultaneous Bluetooth Classic A2DP Sink (music streaming) and HFP (Hands-Free Profile for two-way calling). - The system must switch seamlessly between music and calls when a phone call is received. - Auto-Reconnect: After being paired to a single host device (Mac, iPhone, Android phone, or PC), the ESP32 must automatically reconnect to that device if it gets disconnected or if the ESP32 is restarted. 5. Serial Port Test Keys (CLI Control): Implement a simple command-line interface over the serial port to trigger these specific actions for evaluation: - Pairing Control: Start pairing, Stop pairing, Delete paired device from NVS/ESP32. - Bluetooth Music Playback: Play, Pause. - Volume Adjustment: Increase volume, Decrease volume. 6. MP3 Voice Prompts, Audio Ducking & Call Behavior: - The framework must support playing local MP3 voice prompt files stored in the `main/audio` directory. - During Bluetooth Music (A2DP): When an MP3 voice prompt is triggered, the ongoing music stream must automatically be muted/attenuated by around 60%, and smoothly return to 100% volume once the prompt finishes playing. - During a Phone Call (HFP): The voice prompts must still function. If a voice prompt is triggered while a phone call is active, it is acceptable and expected for the ongoing phone call to be fully muted for the exact duration of the voice prompt. Normal two-way call audio must resume immediately after the prompt finishes. --- ### Critical Terms: "No Cure, No Pay" & Milestone-Based Evaluation We have extensive experience with embedded development contracts and will not tolerate substandard or non-functional deliverables. This project will be strictly run on a fixed-price, escrow-locked milestone basis with a "No Cure, No Pay" policy. Evaluation & Acceptance Criteria: 1. Zero Pre-payments: No funds will be released until code is delivered and fully verified by our team. 2. Compilation Test: The project must import flawlessly into Espressif IDE (v4.3.0+) and compile without any warnings or errors using ESP-IDF 5.5.4 and ESP-ADF 2.8. 3. Hardware & Feature Verification: We will flash the framework onto an ESP32-U4WDH development board. All features (Auto-reconnect, CLI Test keys, A2DP/HFP profile switching, and MP3 audio ducking/muting under internal RAM constraints) must perform exactly as specified. Real audio output must be confirmed. If the delivered framework fails to compile, crashes due to memory leaks/panics, or fails to meet the core functional requirements listed above, no milestone payments will be released, and the contract will be cancelled. By applying to this job, you agree that you are an absolute expert in Espressif audio development and are fully confident in delivering a production-ready framework under these conditions.