Digital audio interface

General microcontrollers such as STM32 can be used to develop digital audio interfaces, but the digital audio output function of general microcontrollers is usually weak and needs to be expanded to some extent. By combining STM32F4 and CPLD chips, high-performance USB digital audio interfaces can be designed.

Due to the limited audio interface function of the STM32F4 chip itself and the inability to directly output DSD signals, the design goal is achieved by connecting an external chip, namely CPLD. This part of the function mainly completes the timing output of audio signals. The USB audio data received from the host is processed in the STM32F4 chip and output to the CPLD chip. Due to the large amount of audio data and high real-time requirements, parallel transmission is achieved through the DMA function of STM32.
In addition to the STM32F4 compatible MCU, AG32VF407 also has built-in CPLD logic inside the chip, which can effectively meet the requirements of digital audio interfaces. The I2S interface is implemented through CPLD simulation, which consumes approximately 0.5K of LUT logic and effectively reduces customer BOM costs. The MCU and CPLD of AG32 communicate at high speed through the internal AHB bus of the chip, far exceeding the STM32+CPLD scheme, effectively meeting the needs of real-time audio transmission.
The schematic diagram of the alternative solution through AG32 is as follows.

Program features:
1. AG32 has a maximum clock frequency of 248MHz and a wide range of peripherals, including five UARTs, two I2Cs, and supports various peripheral modules such as USB, CAN, and SPI channels. With its high-speed instruction execution speed, convenient JTAG debugging method, and low power consumption, it provides a relatively complete platform for data collection and processing design.
2. AG32 has a 3x12 bit ADC with a maximum of 3M SPS (17 channels), 2 DACs, and provides two dual channel comparators.
3. AG32 is initially compatible with STM32 pins, but can be flexibly redefined through configuration files for use by MCU and CPLD in the kernel, thus providing more GPIO ports than STM32.
4. The MCU and CPLD of AG32 communicate at high speed through the internal AHB bus of the chip, which is much faster than traditional SPI.
5. AG32 built-in CPLD can achieve customized logic functions for customers.
6. Available in over 32/48/64/100 packages.