CODEC
Sample List
This chapter introduces the details of the CODEC sample. The RTL87x2G provides the following examples for the CODEC peripheral.
Functional Overview
Uplink Channel (Recording Channel): This device has an analog microphone and two digital microphone inputs with PDM interfaces for recording applications. Downlink Channel (Playback Channel): The monophonic analog DAC output only supports differential mode, used for external audio amplifier connection. CODEC I2S is used as the I2S Slave interface for the internal audio codec. The audio format supports I2S, Left-Justified, PCM Mode-A, and PCM Mode-B.
Feature List
Supports two uplink channels: channel0 / channel1.
Supports one downlink channel: supports analog DAC output.
Configurable uplink and downlink sampling frequencies.
The I2S interface can support audio protocols like I2S, Left-Justified, PCM, etc.
RX supports 8/16-bit data length.
TX supports 8/16/24-bit channel length.
Supports 5-band EQ functions.
Uplink Channel
The uplink path (recording path) is a recording processing module with key functionalities including:
Input Type and Interface: The device is equipped with an analog microphone and two digital microphone inputs with PDM interfaces.
Gain Control: PGA (MIC Gain) can support single-ended and differential mode inputs, providing analog gain of 0/20/30/40dB to amplify the microphone signals.
Power Supply: MICBIAS provides DC bias current for external microphone devices.
Signal Conversion: SDM ADC converts amplified analog signals into digital signals.
Digital Microphone Clock: The DMIC interface provides five configurable clock frequencies (5M/2.5M/1.25M/625k/312.5k Hz) to support finer digital signal processing.
Signal Processing: High-pass filters remove DC components from audio signals and provide multiple frequency corner options to optimize low-frequency response.
Digital Gain and Mute Control: DVOL module provides dynamic control of digital gain from -17.625dB to +84dB and supports dynamic mute control.
Sampling Rate and Audio Adjustment: Supports audio recording up to 16-bit depth and 48kHz sampling rate, with 5-band EQ functionality for audio response adjustment and optimization.
The downlink path (playback path) is a playback processing module with key functionalities including:
Output Mode: Monophonic analog DAC output only supports differential mode for connection to external audio amplifiers.
Signal Conversion: n-bit SDM converts digital signals into n-bit modulated digital signals for digital-to-analog conversion. The DAC PDM module offers flexibility for interfacing with PDM power amplifiers (DM interface) in playback applications.
Gain and Mute Control: DVOL module supports attenuation from +0dB to -65.625dB, and the mute controller can also be dynamically set.
Audio Processing Capability: Supports up to 10-band EQ functions. Supports bit depth up to 24-bit and sampling rate of 48kHz.