/*!
    \file    readme.txt
    \brief   description of SD card read and write test
    
    \version 2024-12-20, V3.31, demo for GD32F4xx
*/

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*/

  This example is based on the GD32450i-EVAL-V1.2 board, it shows how to use SDIO to read or
write to SD card. Firstly, all the LEDs are turned on and off for test. If initialization 
of the card is successful, print out the detailed information of the card by USART. Then 
write a block of data to the card and read. If any error occurs, print the error message 
and turn on LED1, LED3 and turn off LED2. After that, do the lock and unlock operation 
test. Lock the card first and try to erase the data of the card. Then unlock the card and 
erase the card. If any error occurs, print the error message and turn on LED1, LED3 and 
turn off LED2. Last is the multiple blocks operation test. If no error occurs, turn on all
the LEDs.

  Uncomment the macro DATA_PRINT to print out the data and display them through HyperTerminal.
Set bus mode(1-bit or 4-bit) and data transfer mode(polling mode or DMA mode) by commenting 
and uncommenting the related statements.

  The JP5 should be jumped to USART.
