This document introduces how to use low cost small CPLD to implement I2S interface to connect STR7xx SPI peripheral with audio device (codec, ADC, DAC, filter, etc.).
This document details a solution for connecting I2S audio devices (such as codecs, ADCs, or DACs) to STR7xx and STR91x microcontrollers. It proposes using a low-cost CPLD to bridge the I2S protocol with the MCU's SPI peripheral, minimizing CPU load and hardware cost.
| CPLD Device | MAX3000A 32 macrocell |
|---|---|
| CPU Load (STR71x) | 3.9% at 32 MHz MCLK |
| Firmware Footprint | less than 5 Kbytes |
The example CPLD was built for the STR71x and STR750 microcontrollers but can be tailored for STR91x or STM32.
The solution uses very low cost hardware, approximately $1.