Introduction
When developing Bluetooth speakers with Jieli’s audio SoCs, adding custom prompt tones often brings up a few common issues – popping noises during power on/off, unsupported audio formats, etc. This guide walks through these issues and their solutions using the Jieli AC696N development board.
1. Pop/click noise when playing prompt tones during power on or off
- First, listen to the original prompt tone file – is the noise already in the audio itself?
- On the development board, the SDK code already includes the following two lines to handle this (add them if missing):
// Power on: disable PA before ramping up
// Power off: disable PA before shutdown
Explanation:
When the speaker is powered on or off, the amplifier (PA) and speaker can produce a pop/click sound – this is normal behavior. The solution is to disable the power amplifier before the power‑on sequence, and also disable it before shutting down. The SDK example has these lines written by default. During debugging, you can verify whether the pop disappears after adding them.
2. Added prompt tones in different formats – MP3 works, but WTG doesn’t
- Double‑check the file format – don’t accidentally mix up extensions.
- For WTG format, you need to enable the corresponding codec in the configuration tool.
Different tone formats require different encoder support. Enable the codec for WTG if you really need it.
Recommendation: Stick with MP3 for prompt tones – it’s simpler and works out of the box.
Summary
By understanding the power amplifier timing (to eliminate pops) and using MP3 format for tones, adding custom prompt tones on the Jieli AC696N platform becomes straightforward. All steps have been tested on the actual development board.