STM32N657X0 SAI Rx DMA: Callbacks not firing / No clock output

[caglayankml]

Hello everyone,

I'm working with a NUCLEO-N657X0-Q board and trying to read audio data from an INMP441 I2S microphone using SAI2 in Master Receive mode with DMA. I have configured everything in STM32CubeIDE, but the DMA transfer complete interrupts are never firing.

Here is a summary of my setup and the troubleshooting steps I've taken.

Hardware Setup:

• Board: NUCLEO-N657X0-Q
• Microphone: INMP441
• Connections:
  • PE12 -> SCK (SAI2_SCK_B)
  • PE13 -> WS (SAI2_FS_B)
  • PE11 -> SD (SAI2_SD_B)
  • Mic L/R pin is connected to GND.
  • Mic is powered by the board's 3.3V supply.

STM32CubeIDE Configuration (.ioc):

• Project Type: FSBL only (no Appli).
• SAI2_B Configuration:
  • Mode: Master Receiver
  • Protocol: I2S Philips Standard
  • Data Size: 24 Bits
  • Number of Slots: 2
  • Audio Frequency: Set to 16 KHz.
• DMA Configuration:
  • SAI2_B is linked to HPDMA1_Channel0.
  • Mode is set to Circular.
• NVIC Configuration:
  • HPDMA1_Channel0 global interrupt is enabled.
• Clock Configuration:
  • SAI2 Kernel Clock is configured to ~2.048 MHz (derived from PLL2). It is not 0 and not at a very high frequency.

The Problem:

1. HAL_SAI_Receive_DMA() is called and returns HAL_OK.
2. However, the DMA callbacks (HAL_SAI_RxHalfCpltCallback and HAL_SAI_RxCpltCallback) are never triggered.
3. I have placed counter variables inside the callbacks, and they never increment when checked with the debugger. The i2s_buffer remains filled with zeros.
4. This leads me to believe that the SAI peripheral is not generating the necessary clocks (SCK/WS) to communicate with the microphone, which is why no data is being received and no DMA interrupts are generated.

Troubleshooting Steps Taken:

• Disabled Security Isolation: I have commented out the SystemIsolation_Config(); call in main.c.
• Verified IRQ Handler: I confirmed that stm32n6xx_it.c contains the HPDMA1_Channel0_IRQHandler function and it calls HAL_DMA_IRQHandler().
• Verified All Settings: I have double-checked all the configurations mentioned above (Clock, NVIC, DMA, SAI protocol) multiple times.
• Checked Hardware: I have verified the physical wiring.

My Question:

Before I proceed with probing the clock lines with an oscilloscope (which is far away), I wanted to ask the community: Is there a common configuration mistake or an essential initialization step for the STM32N6's SAI peripheral in Master Receive mode that could cause this behavior (i.e., failure to start clock generation)?

For your review, I have attached my main.c project file and screenshots of my HPDMA and SAI configurations.

(Please note: I used an AI assistant to help edit this text, so I apologize for any awkward phrasing.)