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STM32F429 NAND conflict withSDRAM

Question asked by zhou.ning on Oct 21, 2014
Latest reply on Nov 18, 2014 by Clive One
I have a board based on the stm32f429. There is a 16M Bytes SDRAM (MT48LC16M8) and a 32M bytes NAND (NAND128W3A2B) connected to the FMC bus.

I used one area of the SDRAM as the LTCD buffer,such as:

 /* Start Address configuration : the LCD Frame buffer is defined on SDRAM */   
 LTDC_Layer_InitStruct.LTDC_CFBStartAdress = LCD_FRAME_BUFFER;

There is two strange problem:

[1] The nand write/read is always unstable, sometimes went wrong. After months of trying, I finally found that:

The nand operation is ok if I turn off the LTDC controller, namely not using the SDRAM as frame buffer. the command is:

 LTDC_Cmd(ENABLE);

[2] Even I turn off the LTDC controller, if I use the upper 8M bytes of sdram, the nand still generates write error.

To summarize:

The only working nand operation is to satisfy both:

a. Turn off the LCD controller;

b. configure the SDRAM as using 8M bytes only:

  FMC_SDRAMInitStructure.FMC_ColumnBitsNumber = FMC_ColumnBits_Number_9b;
  FMC_SDRAMInitStructure.FMC_RowBitsNumber = FMC_RowBits_Number_12b;

If I configure to use the whole 16M SDRAM like:

  FMC_SDRAMInitStructure.FMC_ColumnBitsNumber = FMC_ColumnBits_Number_10b;
  FMC_SDRAMInitStructure.FMC_RowBitsNumber = FMC_RowBits_Number_12b;

nand will go wrong.

I have researching this problem for months, can't find the answer, could anyone help me out. Even a hint maybe will help me find the solution.

Thank you very much!

If I only use the

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