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ADS7956: General Questions for initialization

A Rau
Prodigy 20 points
Other Parts Discussed in Thread: ADS7956

Hi,

I'm trying to interface the ADS7956 with the Arduino over SPI so I can read the digital converted voltage values over the SPI bus. I'm unsure on how to initialize the chip for Auto-1 mode. I'm not using the Alarm or GPIO. I need to scan all 12 channels of the ADC in ascending order. 

Is it sufficient upon power up to send the mode control register command bits for Auto 1 mode over SPI, wait a clock cycle for the change to take effect, then start reading from the ADC? Or do I need to program both the program register and the mode control registers? If so, which do I program first? I didn't think I needed to set the program register since the default (all channels) matches my desired settings. 

Any help would be appreciated.

Thanks,

A. Rau

  • 0
    TI__Mastermind 25020 points
    Hello A Rau,

    I will consolidate your previous post on to this post, please respond on this post.
    On the datasheet for ADS7956, Table 2, shows the mode control register setting for Auto-1 Mode (Manual mode is explained in Table 1, and Auto2-mode is explained in Table 5). Then, after mode control register, Table3 explains program register settings for Auto1-mode ; I would suggest following that order.

    www.ti.com/.../ads7956.pdf

    In any mode, the device can perform its mux selection in one frame and sampling + conversion is done in the next frame as per the timing diagram in Figure 1. If you select a channel in frame "n", you will sample the data for that channel in frame "n+1" and will get the conversion results for this channel in frame "n+2".

    I hope this helps
    Cynthia