Description
Hi,
I am storing data to an SD-card over SPI with Portenta H7. Running the SdFat “bench” example I only reach about 1.3 MB/s write speed.
I expected more: e.g. the Arduino Due in the SdFat README shows ≈3.9 MB/s, and a forum post in 2023 reports the same ceiling (1763.56KB/Sec) on the GIGA R1 (link:https://forum.arduino.cc/t/sdfat-tests-on-giga-r1/1198629/1).
Test setup
•Arduino Mbed Portenta Boards 4.3.1
• Arduino IDE 2.3.5
• Library: SdFat 2.3.0 (via Library Manager)
• Sketch : SdFat → examples → bench (edits in SdFatConfig.h →#define USE_SPI_ARRAY_TRANSFER 1
#define ENABLE_DEDICATED_SPI 1)
• SPI clock : tried 50 MHz and 60 MHz – speed barely changes
• SD card : 32 GB “Raspberry Pi” (Class 10, U3, V30, A2)
Questions:
Is there a simple configuration change (like enabling DMA) that can improve the SPI write speed?
Is this a documented limitation of Mbed OS's SPI implementation?
As I have limited experience with embedded systems, so step-by-step instructions or links would be greatly appreciated.
Thank you for your time and assistance!
Best regards