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IWR1443: TIDEP-0091 communication sequence

Julia Sánchez Sánchez
Prodigy 115 points
Part Number: IWR1443
Other Parts Discussed in Thread: TIDEP-0091,

Hello,

I'm studying the TIDEP-0091 Design Guide. On point 2.2, we can read the following:

"GPIO-1 MSP432 output to the mmWave sensor input for mode control, 1=Calibration, 0 = Functional cycle"

Then, on point 2.6, on Figure 7: TIDEP-0091 Level Sensing Control and Communication Sequence, we can see the following:

We can see on the description of the operation on the top, that after responding to mode, the IWR1443 performs calibration. What we can observe in the signals diagram is that there's an interval after "MMwave sensor start Boot" and then GPIO-1 changes its state from 0 to 1 (from the text, we can interpretate that's the period at which the MSS software is performing the calibration).

But according from the first definition, shouldn't it be the opposite? I thought that pin state would be changing from 1 to 0 after calibration is complete, but maybe I'm not fully understanding the pin functioning.

I've been looking at IWR1443 Datasheet and there is no specification that GPIO1 is an active low signal.

I want to know to be sure to know how to implement these signals from the MCU.

Best regards,

Julia S.  

  • 0
    TI__Genius 14295 points

    Hello Julia,

    You can see more info in the source code comments when downloading the code.

    GPIO1 is actually indicating whether a full calibration is being run or if the calibration is being restored from flash. You can see the other GPIO toggles in the code as well.

    Regards,

    Jackson

  • 0 in reply to Jackson Thomas
    Prodigy 115 points

    Hello Jackson,

    Thanks for your answer. I understand what you are explaining. My question is if, if the pin GPIO_1 is configured as described in the code, shouldn't its value be 0 in the Figure 7 I included in my initial comment?

    If the measurement cycle is a normal one, shouldn't it be taking the full calibration from flash and doing just a partial one (and therefore its value be 0)?

    I don't know if I'm not understanding the pin functioning or if I'm not understanding the situation described in Figure 7. I think what's happening is one of these two situations.

    Best regards,

    Julia.

  • 0 in reply to Julia Sánchez Sánchez
    TI__Genius 14295 points

    Ok I see your question now. The GPIO1 is being set by the MSP432 device / host processor. So this will only transition at startup of the host device. Then it will remain constant unless modified by the 432. The IWR device only reads this GPIO. The calibration is actually performed after loading the code since that is when the GPIO signal is read. So the transition doesn't mean anything in the diagram, that is just the MSP432 booting as well. 

    Hope that helps.

    Regards,

    Jackson 

  • 0 in reply to Jackson Thomas
    Prodigy 115 points

    Hello Jackson,

    Thanks for your quick reply.

    Okay, so, if my understanding is correct, what you mean is that in Figure 7 process, signal from GPIO1 is only being relevant on the moment of "mmWave sensor start Boot", when it's read as a 0 and therefore a partial calibration + functional cycle is executed. Then, it's later change to value 1 wouldn't affect the IWR process. What I don't get is why the 432 would change this value in the middle of the cycle.

    Was this what you meant, or am I understanding it incorrectly?

    Thanks again and best regards,

    Julia Sánchez.

  • +1 in reply to Julia Sánchez Sánchez
    TI__Genius 14295 points

    Actually from the image above it would be latched as a 1 for full calibration. The IWR sensor reads the GPIO during initialization of the code, which comes right after the load program time in the bottom. The diagram is a little confusing as the transition of the GPIO1 signal is not important. I think it just shows that to indicate it is a signal. Whatever the GPIO is at read time (the code snipped above), which comes during the start of the run program section, is the value that is used.

    Regards,

    Jackson

  • 0 in reply to Jackson Thomas
    Prodigy 115 points

    Okay, now everything is clear to me.

    Thank you very much for your attentive responses.

    Best regards,

    Julia.