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marcogrossi89
marcogrossi89
Associate III
September 18, 2017
Question

STM32 digital input frequency

  • September 18, 2017
  • 3 replies
  • 1041 views
Posted on September 18, 2017 at 17:58

Hello, my problem is I need to acquire a waveform at high frequency (sampling frequency in the order 35 to 50 MHz carried out by fast external ADC). I would like to use an high performance STM32 microcontroller (such as F3 or F4) to acquire 8 bit digital inputs (ADC output) and transfer them to memory by DMA however I do not know what is the maximum frequency for the operation'DMA read input port and transfer to memory'.

Anyone can help?

Thanks.

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    3 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    September 18, 2017
    Posted on September 18, 2017 at 18:11

    The DCMI port is supposedly capable of 54 MHz operations, but you'll be hard pressed to consume/process data at such rates. How deep of a sample buffer are you looking at?

    FIFOs can also be used from high rate capture

    http://www.averlogic.com/AL422B.asp

     
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    marcogrossi89
    marcogrossi89Author
    Associate III
    September 18, 2017
    Posted on September 18, 2017 at 18:22

    The analog signal is 6.78 MHz and is sampled by an external pipelined fast ADC (50 Msps). What I need is to acquire the ADC 8 bits digital outputs with a STM32 input port and transfer the byte to memory. If I use a 48Mhz clock for ADC then I can acquire about 7 samples per period. I think a buffer of 70 bytes (10 periods) should be enough.

    Naturally sampling with higher frequency would provide more samples per period but I have no idea how to do it.

    Tesla DeLorean
    Tesla DeLorean
    Guru
    September 18, 2017
    Posted on September 18, 2017 at 18:51

    At 48 MHz you need to be looking at the DCMI peripheral and how to utilize that.

    If you use the FIFO device, you could access that via the FSMC/FMC

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