JL JieLi AC696N Development Board – Advanced Power Management: Core Voltage Adjustment and Long-Press Reset

Introduction

Previously, we discussed reset source querying and I/O wake-up configuration—these are the basics of low power. However, in real products, there are a few more power management pitfalls worth addressing separately: when to raise the core voltage, how to control the SD card power pin, and how to configure long-press reset to avoid false triggers. These settings may seem minor, but if done incorrectly, they can cause mysterious problems—like intermittent crashes when running high-frequency applications, or long-press reset that's either too sensitive or too sluggish, hurting the user experience.

Recently, while debugging a product with SD card playback on the AC696N development board, I went through these configurations and organized them here for future reuse.

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I. When Do You Need to Raise the Core Voltage?

When the chip runs at higher frequencies or under heavy load, you may need to increase the core voltage (SYSVDD) to ensure stability.

How to do it:

1. In clock_manager.c, set clock_mode to CLOCK_MODE_USR

2. In the set_up.c file, adjust the SYSVDD_VOL_SEL configuration item.

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II. SD Card Dedicated Power Pin Control

The SD card power pin (SDPG) has a dedicated control function: sdpg_config(int enable).

• enable = 0: Set to high-impedance state
• enable != 0: Enable strongest drive mode to ensure stable SD card power supply

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III. Configuring Long-Press Reset Function

By editing the isd_config.ini file, you can enable or configure a long press on a specific I/O pin to trigger a hardware reset.

Configuration format: RESET=<port>_<time>_<level>

• <port>: e.g., PB01
• <time>: 00 (disabled), 01, 02, 04, 08 (seconds)
• <level>: 0 or 1, the active level to trigger reset

Example: RESET=PB01_02_0 means long press PB01 for 2 seconds, low level triggers reset.

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Summary

For the core voltage: if your product runs standard Bluetooth audio applications, the default voltage is generally sufficient. However, if you add SD card support, dual-mode Bluetooth, plus some extra processing, and you experience occasional crashes under load, try raising the SYSVDD voltage slightly—this often solves the problem.

The SDPG pin control is straightforward: use the strongest drive when SD card is present, otherwise set to high-impedance to save power. Don't miss this configuration.

For long-press reset duration, 2 or 4 seconds is recommended. Too short risks false triggers; too long becomes tiresome for users.

Verify these parameters on the AC696N development board first, then port them to your product board—this will save significant debugging time.