Hello everyone,
I'm trying to interface a microSD card using FileX on a custom board with an STM32H747IIT6.
The microSD card is connected to the SDMMC1 peripheral using a 4-bit wide bus, with external pull-ups on the data lines.
Initially, we used FATFS to interface with the microSD card, which worked flawlessly. Now, as we transition to Azure, we want to use FileX. Additionally, we are using NetXDuo to create a web server, with the SD card serving as storage for web server files.
The issue occurs when calling fx_media_open (app_netxduo.c, line 522), which almost always returns error code 0x90 (except for a single successful attempt going step by step via the debugger).
Current Configuration:
- SDMMC1 pin speed: medium
- SDMMC1 peripheral clock: 40 MHz, scaled down to 10 MHz using a divider (set to 4)
- SD card: SanDisk 64GB, formatted in exFAT (exFAT support is enabled)
Troubleshooting Steps Taken:
- Adjusted clock speed via divider (1–40 MHz)
- Changed pin speed (medium, high, very high)
- Tested different microSD cards (4–64GB, all SanDisk)
- Lower-spec cards failed with a different error code (0x03)
- If formatted with FAT, the exFAT option was disabled
I would greatly appreciate any insights or suggestions on how to resolve this issue.
Best regards,
OskarP.
