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AMC1210: is SPI deactivated via RST is low?

Christian Sch.
Prodigy 90 points
Part Number: AMC1210


Tool/software:

Hello,

we use the AMC1210 with Interface Mode SPI by tying M0 and M1 to ground. How does the SPI interface (CS=CS, WR=CLK, RD=MOSI, AD0=MISO) act while the AMC1210 is in reset by tying RST to ground?

  • Does it react on CS and CLK and read MOSI data? Does it activate AD0 to drive MISO data?
  • Or does it ignore everything and any data at MOSI and does it leave AD0 (MISO) in high impedance state?

Thanks and best regards

Christian

  • 0
    TI__Guru**** 182021 points

    Hi Christian,

    To be honest, I don't believe the /RST input will completely deactivate the SPI function.  The /RST input resets all internal registers to their default state, so all of the Filter Module data registers will be set to 0x00..00.  If the /CS pin is driven low and you try to write to any register, if /RST is also low, the register will still hold its default reset state.  Both SCLK and MISO will be held in tri-state if /CS is high.

  • 0 in reply to Tom Hendrick
    Prodigy 90 points

    Hi Tom,

    and what about MISO? Is it in tri-state even if /CS is low while /RST is low?

  • 0 in reply to Christian Sch.
    TI__Guru**** 182021 points

    From what I can see, MISO will drive 0x0000 even if /RST is low.  Can I ask what you are trying to do in the end?  The /RST pin would be driven by your controller along with /CS, MOSI and SCLK.  If you are driving the /RST pin, why would you also be trying to communicate through the SPI interface?

  • 0 in reply to Tom Hendrick
    Prodigy 90 points

    Hi Tom,

    I want to substitute the AMC1210 by another emulated SPI slave to perform fault injections for software testing. I was hoping it would be possible to disable the AMC1210 completely by /RST = low so I can just connect the emulated SPI slave in parallel to all SPI signals.

    But if AMC1210 does not leave the MISO in high-impedance state, I cannot drive MISO simultaneously by another instance.

    Christian

  • 0 in reply to Christian Sch.
    TI__Guru**** 182021 points

    Hi Christian,

    I can try to find a way to verify for sure on my end, but if you have hardware available, simply trying to drive a square wave onto MISO with RST and CS held low should show you if the pin is actually tri-stated.  From the detail that I have available, I don't see where the RST pin actually influences the SPI connectivity, it appears to only interact with the internal register settings.