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ADS1278 SCLK和CLK之间的倍数关系问题

Other Parts Discussed in Thread: ADS1278

最近在使用ads1278做采集,按照DS上的说法 SCLK要是CLK的  1 , 1/2 ,1/4倍 。但实际按照这样设置的时候发现读出的数据有问题。  按道理来说spi的sclk速度应该要高于采集时钟clk才可以的啊,实际测试也验证了这一点。但是为什么ds上说sclk要等与或者小于clk ?

  • 你应该是理解反了吧, 我看文字下面的时序图的

    SCLK
    The serial clock (SCLK) features a Schmitt-triggered
    input and shifts out data on DOUT on the falling
    edge. It also shifts in data on the falling edge on DIN
    when this pin is being used for daisy-chaining. Even
    though SCLK has hysteresis, it is recommended to
    keep SCLK as clean as possible to prevent glitches
    from accidentally shifting the data. When using
    Frame-Sync format, SCLK must run continuously. If it
    is shut down, the data readback will be corrupted.
    The number of SCLKs within a frame period (FSYNC
    clock) can be any power-of-2 ratio of CLK cycles (1,
    1/2, 1/4, etc), as long as the number of cycles is
    sufficient to shift the data output from all channels
    within one frame. 

  • 这个怎么理解。

  • 您好,
    CLK是系统时钟,SCLK是SPI的时钟,fSCLK最大等于fCLK。您实际测试验证的时序波形可以分享出来看一下是什么原因吗