SD card write using SDIO (4 bit) with DMA enabled is making system fail. I suspect cyclic write of around 200 bytes at 100 Hz is leading to bus contention issue or so.

[DevBee]

Am using sTM32F4 Discovery board with extension board for RS232 interface and SD card.

RS232 is also using DMA and its priority is higher than that of SD card DMA channel priority. The tasks working on RS232 interface and SD card log are different too. When I enable SD card logging (DMA enabled), the system behaviour is erratic as if due to DMA channel contention issues, other tasks using DMA channel are failing leading to system failure.

Kindly guide how to resolve this issue.