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TIDA-00489: Current peaks caused by HWI detecting a movement

Genius 4205 points

Replies: 8

Views: 466

Part Number: TIDA-00489

Hey guys,

we are using the TIDA 00489 layout and have some test sensors here (no changes made to layout). We are counting the movements detected by the sensor using HWI and increment a counter each time this HWI is triggered. We are using the sensor collector TI 15.4 stack for network communication, however the current measurements we have done so far completely coincide with the ones specified by TI regarding idle, polling peaks, data message peaks a.s.o. But we noticed minor peaks, as the right one in the below picture. It takes ca. 5ms and goes up to approx. 2.4mA.

When the sensor was covered, so no motions were detected, no such peaks were measured, if a lot of movements have been present, the number of measured values by the sensor matched the amount of small peaks we could see in the graph over 10s. So we are very sure, that these peaks originate from the HWI.

I was wondering if we could lower the current consumption by means of doing some changes in the software? Since we are only incrementing a counter maybe during the ISR we could apply some further power restrains?

I welcome any suggestion

kind regards

Slev1n

  • Expert 8505 points

    When you were doing the power measurements with lots of movement, were most of the peaks the first peak (800uA) or were they the second peak (2.4mA)?  


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  • In reply to clam:

    Hey Clam,

    it looked like this. So most of the peaks are around 2.4mA. The time resolution of the measurement device is 500µs.

  • Guru 106355 points

    In reply to Slev1n:

    Hi Slev1n,

    Have you considered using the SensorController?

    Regards,
    Fredrik
  • In reply to Fredrik K:

    Fredrik K

    Have you considered using the SensorController?

    I have, but

    1. The layout would have to be changed because the comparators are not connected to pins available in the sensor controller
    2. As discussed in this thread, the sensor controller can only handle 1 HWI, but I have two comparators causing HWIs if a movement is detected.

    So, do you guys see similar current peaks using HWIs? Any power setting to lower it?

    kind regards

    Slev1n

  • In reply to Slev1n:

    Any further suggestions? Do you see the same behavior in the current consumption if a HWI is triggered?
  • Guru 106355 points

    In reply to Slev1n:

    Hi Slev1n,

    A HWI would wake up the entire system, so it is expected that this draws around 3 mA.

    Regards,
    Fredrik
  • In reply to Fredrik K:

    Hey Frederik, thank you for the answer. I have one further easy question, looking into the power modes of the CC1310, I was wondering if I can set the power mode during ISR to idle instead of active, then the CPU would still be off, but current of CC1310 is at 570µA. Am I able to make simple mathematic operations like, adding, subtracting one number or getting RTC ticks in this mode or is the CPU necessary for that?

  • Guru 106355 points

    In reply to Slev1n:

    Hi Slev1n,

    That is not possible, you need the CPU for calculations and logical operations.

    Regards,
    Fredrik

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