STM32L476 Nucleo-64 cannot read USB drive

[kevinyy]

大家好，

我正在使用一塊 STM32L476 Nucleo-64 開發板。我想直接將 USB 隨身碟連接到開發板的 USB 連接埠來讀取它。

我正在使用開發板的UART檢查USB讀取操作是否成功。我成功讀取了一個16GB的USB驅動器，但當我嘗試讀取一個256GB的驅動器時卻失敗了。

這對我來說很奇怪。有人遇到類似的問題嗎？或是有什麼建議可以解釋一下是什麼原因造成的？

任何幫助都將不勝感激！

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Google Translate:

Hello everyone,

I'm using an STM32L476 Nucleo-64 development board. I want to connect a USB flash drive directly to the board's USB port to read it.

I am using the UART of the development board to check if a USB read operation is successful. I successfully read a 16GB USB drive but failed when I tried to read a 256GB drive.

This seems strange to me. Has anyone encountered a similar problem? Or has any suggestions on what could be causing this?

Any help would be greatly appreciated!

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[FBL]

Hi @kevinyy 

This could be linked to several factors. First, reading from large drives may require larger buffers or more RAM for FATFS operations. STM32L476 has limited RAM (80KB SRAM total). Check if it's insufficient RAM that leads to reads failure.

[Pavel A.]

In addition to what @FBL wrote, larger drives can use a different USB protocol (UASP instead of USBSTOR). Existing ST examples don't demonstrate this protocol.