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ADS1294 RESET pin, any pull-up or -down?

Vala
Expert 1110 points

Hi,

I didn't find the answer to this question. Is there any internal pull-up resistor for the RESET pin in ADS129x? Can I leave it floating? I will be using the RESET command through SPI.

-Vala

  • 0
    TI__Mastermind 38745 points
    Hey Vala,

    There is no internal pull-up. You must tie it high in hardware.

    Brian
  • 0 in reply to Brian Pisani
    Expert 1110 points

    Thanks for your answer Brian. The interesting thing is that at least so far my device is working with RESET pin floating. I can read/write registers and the outputs of all VCAPs are as expected. The RESET pin also sets the registers to their default values right? For me it does not happen and the registers are read with the values that I have written (well of course that can be random). Although I don't see the DRDY signal after setting some registers and issuing the START and RDATAC commands.

  • 0 in reply to Brian Pisani
    Expert 1110 points
    May I recommend to mention this in the datasheet? In the 'Pin Configuration' table several pins are labeled to be connected to high or low rails. Is it a good idea to label the RESET pin too?

    Could you also comment on the START pin? Should it be tied high or low too?
  • 0 in reply to Vala
    Expert 1110 points
    About the START pin I found the following sentence in the datasheet:

    "When using the START opcode to begin conversions, hold the START pin low".

    And here is the behavior of the chip in my device with the RESET pin is floating if any one is interested in future:
    Although I can read/write the registers and their values never change to their default values, the DRDY signal never changes its state even after power up that it should be in the continuous reading mode. In this phase, I cannot read the registers (since the chip is in continuous mode). But when I send a STOP command, I can read the registers. After sending START command the chip again does not send any signal on DRDY and I can even read the register values (without sending a STOP command).

    I guess this is what you can the "unpredictable state" which happens when the RESET pin is floating.

    -Vala
  • 0 in reply to Vala
    TI__Mastermind 38745 points
    Vala,

    Thanks for the commentary. Looks like you've learned the behavior of the START pin. The advice about indicating the RESET pin's behavior in the pin assignments table has been noted.

    Regards,
    Brian