Audio Pipeline Refactoring

Oct 13, 2025 by wbrum.org 128 views

Introduction

The Micro:Bit is a popular microcontroller board designed for education and hobbyist projects. It features a range of peripherals, including a display, serial communication, and audio capabilities. However, when attempting to refactor the audio pipeline, a programme freeze issue arises after a reset. In this article, we will delve into the problem, explore possible causes, and provide a solution to resolve the issue.

Problem Description

The programme freezes after a reset, but only when the audio pipeline is refactored. The display shows the character A correctly, but the programme gets stuck in the first call to uBit.audio.levelSPL->getValue(). This issue is specific to the refactored audio pipeline and does not occur when the programme is run after a cold power-up.

Code Analysis

The provided code snippet is a simple programme that initializes the Micro:Bit, enables the audio, and then enters an infinite loop to print the audio level to the serial console. The code is written in C++ and uses the Micro:Bit library.

#include "MicroBit.h"

MicroBit uBit;

int main() {
    uBit.init();

    uBit.display.print("A");
    uBit.serial.printf("\nstart\n");
    uBit.audio.enable();
    while (true) {
        uBit.serial.printf("%d\n", (int)uBit.audio.levelSPL->getValue());
        uBit.sleep(20);
    }
}

Configuration File

The configuration file is a JSON file that specifies the target and configuration settings for the programme. In this case, the target is set to codal-microbit-v2 with the audio-refactor branch, and the MICROBIT_BLE_ENABLED and MICROBIT_BLE_PAIRING_MODE settings are disabled.

{
    "target": {
        "name": "codal-microbit-v2",
        "url": "https://github.com/lancaster-university/codal-microbit-v2",
        "branch": "audio-refactor",
        "type": "git"
    },
    "config":{
        "MICROBIT_BLE_ENABLED" : 0,
        "MICROBIT_BLE_PAIRING_MODE": 0
    }
}

Possible Causes

Based on the provided information, there are several possible causes for the programme freeze issue:

Audio Pipeline Refactoring: The refactored audio pipeline may be causing the issue. It is possible that the new audio pipeline is not properly initialized or is not functioning correctly.
Reset Issue: The reset button may be causing the issue. It is possible that the reset button is not properly handled or is causing the programme to get stuck.
Display Issue: The display showing the character A correctly may indicate that the display is functioning correctly, but the programme is getting stuck in the audio level retrieval.

Solution

To resolve the programme freeze issue, we need to investigate the possible causes and provide a solution. Here are some possible solutions:

Revert Audio Pipeline Refactoring: Revert the audio pipeline refactoring and see if the issue is resolved.
Modify Reset Handling: Modify the reset handling code to properly handle the reset button press.
Investigate Display Issue: Investigate the display issue to see if it is related to the programme freeze.

Commit History

The commit history for the codal-microbit-v2 repository shows that the audio-refactor branch was created on commit 4a5aab37f97c7c5048cb7e317f461391da629cb1.

Conclusion

Q: What is the programme freeze issue?

A: The programme freeze issue occurs when the programme gets stuck after a reset, but only when the audio pipeline is refactored. The display shows the character A correctly, but the programme gets stuck in the first call to uBit.audio.levelSPL->getValue().

Q: What are the possible causes of the programme freeze issue?

A: The possible causes of the programme freeze issue are:

Audio Pipeline Refactoring: The refactored audio pipeline may be causing the issue. It is possible that the new audio pipeline is not properly initialized or is not functioning correctly.
Reset Issue: The reset button may be causing the issue. It is possible that the reset button is not properly handled or is causing the programme to get stuck.
Display Issue: The display showing the character A correctly may indicate that the display is functioning correctly, but the programme is getting stuck in the audio level retrieval.

Q: How can I resolve the programme freeze issue?

A: To resolve the programme freeze issue, you can try the following:

Revert Audio Pipeline Refactoring: Revert the audio pipeline refactoring and see if the issue is resolved.
Modify Reset Handling: Modify the reset handling code to properly handle the reset button press.
Investigate Display Issue: Investigate the display issue to see if it is related to the programme freeze.

Q: What is the commit history for the `codal-microbit-v2` repository?

A: The commit history for the codal-microbit-v2 repository shows that the audio-refactor branch was created on commit 4a5aab37f97c7c5048cb7e317f461391da629cb1.

Q: What is the configuration file for the programme?

A: The configuration file is a JSON file that specifies the target and configuration settings for the programme. In this case, the target is set to codal-microbit-v2 with the audio-refactor branch, and the MICROBIT_BLE_ENABLED and MICROBIT_BLE_PAIRING_MODE settings are disabled.

{
    "target": {
        "name": "codal-microbit-v2",
        "url": "https://github.com/lancaster-university/codal-microbit-v2",
        "branch": "audio-refactor",
        "type": "git"
    },
    "config":{
        "MICROBIT_BLE_ENABLED" : 0,
        "MICROBIT_BLE_PAIRING_MODE": 0
    }
}

Q: What is the code snippet for the programme?

A: The code snippet is a simple programme that initializes the Micro:Bit, enables the audio, and then enters an infinite loop to print the audio level to the serial console.

#include "MicroBit.h"

MicroBit uBit;

int main() {
    uBit.init();

    uBit.display.print("A");
    uBit.serial.printf("\nstart\n");
    uBit.audio.enable();
    while (true) {
        uBit.serial.printf("%d\n", (int)uBit.audio.levelSPL->getValue());
        uBit.sleep(20);
    }
}

Q: What is the solution to the programme freeze issue?

A: The solution to the programme freeze issue is to investigate the possible causes and provide a solution. The possible causes are:

Audio Pipeline Refactoring: Revert the audio pipeline refactoring and see if the issue is resolved.
Reset Issue: Modify the reset handling code to properly handle the reset button press.
Display Issue: Investigate the display issue to see if it is related to the programme freeze.

By following these steps, you can resolve the programme freeze issue and get your programme running smoothly.