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tofighi
tofighi
Associate
October 30, 2016
Question

STM32F429 & SDRAM

  • October 30, 2016
  • 3 replies
  • 868 views
Posted on October 30, 2016 at 09:45

Hi

Im working with stm32f429 and i want to have 2 MT48LC16 SDRAM for my TFT_LCD and yet cause of some conflicts, i can only use 1 FMC SDRAM on cube. is it possible to do this? if yes how must i determine the address and DQML and DQMH pins on the 2 SDRAM? 
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    3 replies

    slimen
    slimen
    Visitor II
    October 31, 2016
    Posted on October 31, 2016 at 19:01

    Hello,

    You can start from an FMC_SDRAM working example under STM32CubeF4:

    \STM32Cube_FW_F4_V1.13.0\Projects\STM32F429I-Discovery\Examples\FMC

    Refer to the datasheet and reference manual related to your device, they will be your support about DQML and DQMH pins.

    Regards

    tofighi
    tofighiAuthor
    Associate
    November 1, 2016
    Posted on November 01, 2016 at 08:52

    Hi 

    thank you for your response but the examples for the discovery kit is about how to read or write form ONE SDRAM, but my question is how can i have 2 SDRAMs instead of one and yet only use one FMC clk and chip enable ...

    best regards

    Mariya 

    ST Renegade
    ST Renegade
    Associate
    November 3, 2016
    Posted on November 03, 2016 at 13:43

    Hello Trinity,

    In such a case I highly recommend to use the STM32CubeMX tool, which checks the used pins for you etc. to avoid some conflicts between already used pins.

    In case of the SDRAMs, there are some lines which are common (shared) for both memories (data, address etc.) and lines which are unique for each memory (write eneable for instance). But as said, STM32CubeMX will help you with this. :)

    Just one more remark, as you are going to use two memories connected in parallel, pay attention to your layout and make sure the memories are properly terminated etc. While one memory will be active (the latter will stay in high impedance state), the signal will still be transmitted to both devices. This can lead to reflections on the lines due to improper terminations etc. On the internet you will find a lot of application notes from TI, Analog devices, NXP how to design high speed circuits etc.

    I hope my answer helps you to move forward.

    Have a nice day,

    Renegade

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