STM32H723VGT6 DMA2 Controller Fails Silently After Prolonged Operation – No Error Flags Reported

[peter_zhly]

Problem Description:
MCU Model: STM32H723VGT6
DMA Configuration:

• DMA1/DMA2 handles 15 DMA channels in total:
  • 5 UARTs (TX + RX)
  • 4 additional UART RX channels
  • 1 PWM channel (TIM15 CCR1 via DMA)
    Observed Failure:
    After 10–60 minutes of normal operation, ​all peripherals using DMA2 stop functioning:

1. ​UARTs: RX overrun errors occur (ORE flag set in ISR).
2. ​PWM (TIM15 CCR1):
   • DMA circular mode remains active (Half/Complete Transfer interrupts trigger normally).
   • SxNDTR counts correctly, but ​CCR1 register data never updates (verified via debugger).
3. ​No DMA Error Flags:
   • TEIF (Transfer Error), FEIF (FIFO Error), and other error flags in DMA_LISR/HISR remain cleared.

Key Observations:

• Failure ​suggests DMA2 loses access to data bus without triggering error detection mechanisms.
• Issue persists across multiple boards, ruling out hardware defects.

Troubleshooting Performed:

1. DMA buffer addresses confirmed in AXI SRAM (0x24000000) with MPU full-access permissions.
2. Interrupt flags (TCIF, HTIF) cleared properly in ISRs.

Request:
Has anyone encountered similar DMA2 silent failures? Any insights into:

• Potential AXI bus arbitration conflicts?
• Hidden errata related to DMA2 bus access?
• Debugging techniques to capture transient bus faults?

Thanks in advance for your expertise!