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Fastest sampling rate of ADC to TMS320C5505

Binglin Li
Prodigy 50 points
Other Parts Discussed in Thread: TMS320C5505

Hi, I'm working on the TMS320C5505 zDSP USB stick. The 10-bit SAR ADC on the DSP board has a maximum of sampling rate 62.5KHz and is not fast enough for use. So I need to connect an extra ADC through the IO pins. The ideal sampling rate is 100MHz. But the time for SPI inputs operate max at 1/40ns=25MHz. I considered to use 8 GPIO pins in parallel to interface with the 100MSPS ADC. As I know, the min time for GPIO data inputs is 2 cycle duration. Does it mean when I set the CPU clock at 100MHz, the max sampling rate of ADC that I can use is 50MHz? How can I use the DSP board to connect to 100MSPS ADC? If can't, what is the max sampling rate of ADC I could use? Thanks.

  • 0
    TI__Mastermind 23785 points
    The clock rate of the SAR module must not exceed 2MHz, documented in User's Guide. GPIO input high pulse duration minimum is spec'ed as 2C and low duration is C. C is SYSCLK in ns. Thus a complete value high-low-high pulse is 3C. This is spec'ed in Data Manual's GPIO section.
    Regards.
  • 0 in reply to Steve Tsang
    Prodigy 50 points

    Thanks, Steve. I am concerned with the sampling rate of ADC because I want to know the highest sampling rate of the ADC that I can use. It seems that 100MSPS ADC cannot be connected directly to the DSP board through IO because the IO data inputs are not fast enough.

    Regards,

    Binglin Li