In page 13 of the DWM1001 datasheet, there is a graph of power consumption during TWR. I assume this graph if for a tag in stationary detection (so it could go to deep sleep between TWRs). I assume also this is the consumption of only the isolated DWM1001 module.
When viewing this graph, one can assume a medium value of about 40mA during 10ms. These values will give an average current consumtion of about 0.4 mA when the module is in stationary detection and there is a TWR process each second (40 mA x 0.010 s / 1s = 0.4 mA). This value is really low, as with an small battery of 150mAh, the tag will be alive for at least 250 hours (150mAh/0.4mA = 375 hours ).
I would like to know if this calculation is realistic, or one should consider another consumption sources in the DWM1001, as the Bluetooth, processor, accelerometer,…
Can you give us a reallistic estimation of average consumption when the tag is in stationary detection and there is a TWR process each second, including the consumption of Bluetooth, processor, etc.
If dissabling the Bluetooth capabilities, how will the average consumption will be improved?
Could you give us some insight of how to configure the analog inputs of the nRF52 (in the user code space) to measure the voltage of a battery?
Thank you very much in advance for the replies
Epenciso
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And, sorry, another question:
What means ‘Responsive mode’ in a tag? (i am not able to find an explanation…)
According to my measurements, with 1 Hz ranging and Bluetooth off the average current is approx. 380 uA, depending on the input voltage. With BT on it is almost doubled, but with default firmware the tag turns BT off after a while, so unless you really need it all the time, you can work with this consumption.
If you can use slower update rate, the consumption does gown rapidly, being approx. only 18 uA with 30s rate. With 100ms it goes up almost to 4 mA.
Deep sleep current is actually 4 uA (or even a bit less).
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See section 4.5 of DWM1001 System Overview And Performance.
Just a remark: My measurements were using 4 anchors, i.e. 1+4+1+4 transmissions, instead of 1+3+1+3 as shown in the document. So, if are using only 3 anchors, it will be even less power hungry.
I have no appropriate instrumentation. Could I ask you to measure the average current when the module is not in stationary detection and there is a TWR process each second? Could I assume the current between ranging processes is the ‘idle’ value of 13mA?
Also, do you know what is the consumption variation with input voltage from 2.8 to 3.6V?
1 Hz w/o stationary detection has approx. 380 uA, as I’ve mentioned. This includes ranging current and deep sleep current between measurements. I’ll post a graph, once measured. Including the difference for 2.8/3.6V.
Please, could you confirm the 380uA value is for non-stationary detection? If the DWM is in non-stationary detection, it shouldn’t go to sleep mode between measurements, but should stay in idle mode (with 13mA of current). Or I am missing something?
Please, could you check this again?
If this is confirmed, what is then the current for stationary detection with 1s rate in ‘stationary update rate’ parameter (and the module is not moving)?
My understanding of stationary detection is, whether the update rate is always the same or depends on device movement. It should have no impact on using deep sleep. That should be influenced by “Responsive mode”, which I am not using with my measurements.