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gbarbour
gbarbour
Associate II
April 27, 2014
Question

STM32F429I-Disco SDRAM disable question

  • April 27, 2014
  • 3 replies
  • 777 views
Posted on April 27, 2014 at 02:22

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I have the STM32F429I Disco board and would like to use more GPIOs than the 27 free ones available in the current board configuration.

I see that 38 pins are used by the SDRAM. I have not been able to find more specific information about how the SDRAM works or what it is used for.

Where can I find explanations of how the SDRAM pins are used and whether or not I can disable the SDRAM function and use the pins for GPIOs?

Thank you.

#stm32f429-sdram-disco
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3 replies

Tesla DeLorean
Tesla DeLorean
Guru
April 27, 2014
Posted on April 27, 2014 at 02:35

The primary reason for SDRAM on the board is to provide a frame buffer for the display, and storing bitmaps, sprites, etc.

The User Manual should describe the pin utilization, and you could remove the SDRAM from the FMC bus. There might also be other boards you can consider, or something breaking out a 176-pin device.
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gbarbour
gbarbourAuthor
Associate II
April 27, 2014
Posted on April 27, 2014 at 04:53

Hello Clive,

Thank you for your quick response. I read about the FMC bus and it was helpful in answering my question. Thank you.

I have been looking at other boards for the last few days and have found only a few that are based on a MCU with an onboard LCD controller. Now that I have found the Disco board isn't quite as flexible as I first thought I will keep looking.

I really like the STM32F429 chip and I considered making or buying a simple adapter board for the larger version, but, I would prefer a pre-made board if I can find the right one. (I am open to suggestions.)

Thank you for your advice.

Tesla DeLorean
Tesla DeLorean
Guru
April 27, 2014
Posted on April 27, 2014 at 05:21

I'd watch WaveShare, the XCore407i is a reasonable board, I suspect they have a 429i model in the works.

I'm not sure how well it would escape the pin choices for the 429, if you can do a straight breakout of the 176-pin device that would give you a clean slate, or work through the pin/peripheral options.

The STM32F429I-DISCO is frustratingly broken from an expansion perspective.
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