Digilent-Compatible I2S Audio Codec

codec front render

Codec PCB Render

codec photo

Assembled Codec PCB

Description

This is an I2S-based Audio Codec that can be connected to 12-pin Digilent peripheral module sockets (PMOD). It provides up to 24-bit, 96kHz stereo audio line-level I/O.

Features:

WM8731 Codec with:
- 8kHz-96kHz sample rate
- 24-bit I2S data
- Selectable SPI or I2C control port
- Internal analog mixing/routing/muting/volume control
Filtered Analog 3.3V Supply
3.5mm stereo line-in and line-out jacks (AC-coupled)
12-pin Digilent-compatible PMOD connector

The signals on the PMOD interface connector are:

Function	Pin	Pin	Function
I2S_SCLK	1	2	MCLK
I2S_SDO	3	4	SPI_CLK
I2S_LRCK	5	6	SPI_DO
I2S_SDI	7	8	SPI_CSB
GND	9	10	GND
+3.3V	11	12	+3.3V

Function	Description
I2S_SCLK	I2S Bit Clock
I2S_SDO	I2S Data to the codec DAC
I2S_LRCK	I2S Word Clock
I2S_SDI	I2S Data from the codec ADC
MCLK	Codec Master Clock
SPI_CLK	Control port clock (SPI or I2C)
SPI_DO	Control port data (SPI or I2C)
SPI_CSB	Control port select (SPI) or address (I2C)

Caveats:

Although the WM8731 Codec supports on-chip headphone amp and MIC input, these functions are not brought out to interfaces.
WM8731 crystal oscillator functionality is not enabled - the MCLK must be supplied by the host FPGA.
User must select SPI or I2C control port by installing either R1 (SPI) or R10 (I2C). Do not install both R1 and R10 simultaneously.

Design Materials

PC Boards are available directly from BatchPCB.

Project Status

2012-04-30: Started Schematic and layout.
2012-05-01: Order PC boards.
2012-05-20: V0.2 PCB assembled.
2012-05-26: DAC driver project posted.
2012-05-27: Loopback driver project posted.
2012-05-28: Delay project posted.
2012-10-29: PCB link posted.

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Last Updated

:2012-10-29

Comments to:

Eric Brombaugh