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ADS1158 mode switching

Desmond Pan
Prodigy 20 points

Other Parts Discussed in Thread: ADS1158

using ads1158 make me confused that if I want to configure it from scan_auto to fixed_mode. because i want to both ways for data collection.

So should I need to reset it again when mode switching?

  • 0
    TI__Mastermind 46290 points

    Desmond,

    You should be able to reconfigure the device by writing to the MUXMOD bit in CONFIG0 (0x00). Optionally you could stop the converter from converting first, reset the converter, configure & validate your registers, and then return to converting. Check out the 'Configuration Guide' section of the Application Information in the device datasheet for more information. 

  • 0 in reply to Kevin Duke
    Prodigy 20 points

    Kevin,

    I want to configere ads1158 working in auto_scan and fixed_mode. but I should initialize it working in auto_scan mode.

    Now I have a problem that can I use LabView to sent cmd to F28335 to change the config of ads1158. And make it work in fixed mode?

  • 0 in reply to Desmond Pan
    TI__Mastermind 46290 points

    Desmond,

    I'm having a hard time understanding exactly what your issue is here. If you can provide more information it'll be easier to help you.

    • Precisely, what do you want to do?
    • What have you tried to do to implement that? What happens?
    • What is your particular concern about using LabVIEW along with your F27335?

    I'm not sure in practice how friendly the ADS1158 is with switching modes on the fly, which seems to be your issue here. I think your best modus operandi is going to be issuing resets to ensure successful re-configuration of the device, if for no other reason than a clean implementation. You sequence should look like this:

    1. Reset the serial bus by raising CS high. This puts the serial bus in a known state so we know precisely what is being written to the device every time.
    2. Stop any potentially active conversion sequence. This isn't completely necessary but it ensures that the channel sequence hasn't advanced to an unexpected channel while the device has been configured in auto-mode. Additionally, this helps guarantee that the digital filter is reset.
    3. Reset the device. Again, not completely necessary but it ensures a known working state for the device.
    4. Using the MUL bit write your complete configuration set to all of the relevant registers.
    5. Read back the register settings to ensure a valid write.
    6. Begin using the device.

    When it's time to change the mode of operation from auto-scan to fixed or the other way around you can write to MUXMOD to change the conversion mode. My memory is fuzzy with respect to whether this action clears out the digital filters or not. If it does, you should have no problems. If it doesn't and you expect for the first conversion result to be correct then you need to stop the device from converting. If an invalid conversion result is no problem you can keep chugging along.

    What is your application? Why do you need to change modes? How fast do you need to change modes?