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Visitor II
May 19, 2025
Question

STM32H747: SAI with DMA on M7 core causes gaps in I2S stream, works fine on M4

  • May 19, 2025
  • 2 replies
  • 351 views

Hi everyone,

I'm working on a project based on the following STM32H7 LwIP example:
https://github.com/stm32-hotspot/STM32H7-LwIP-Examples/tree/main/STM32H747_Disco_M7_ETH

In addition to the Ethernet functionality, I’ve enabled the SAI peripheral with DMA to transmit audio via I2S. I’ve noticed a problem:

When I run the SAI with DMA on the Cortex-M7 core using FreeRTOS, the audio stream contains gaps or dropouts.

However, when I move the exact same SAI/DMA initialization and logic to the Cortex-M4 core, the audio output is perfect with no gaps.
Has anyone experienced similar issues when using DMA for audio on the M7 core with FreeRTOS?

Any suggestions would be greatly appreciated.

Thanks in advance!
TG808

2 replies

Technical Moderator
May 20, 2025

Hello @TG808 

Could you run your code without FreeRTOS and LWIP and check if the issue is still there?

Did you refer to the example below and get inspired from it: 

STM32CubeH7/Projects/STM32H735G-DK/Examples/SAI/SAI_AudioPlay at master · STMicroelectronics/STM32CubeH7 · GitHub

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Visitor II
May 14, 2026

Hi TG808,

Did you have any success in solving this problem? I am currently using the SAI configured in Master receive for I2S on a H7 and am facing the same problem.