General > General Technical Chat
IoT consumption logging/profiling
PlainName:
--- Quote ---Does anyone have some kind of experience with that EMK850S+?
--- End quote ---
I've been hoping someone like you might get one to find out and let us know 8)
LogicalDave:
I don't have experience with the EMK850S, but I have used several other devices for dynamic power measurement. The best is the Joulescope; for something much less expensive, you could try the Nordic Power Profiler Kit (NRF-PPK2: https://www.nordicsemi.com/Products/Development-hardware/Power-Profiler-Kit-2) but I believe it only works up to 1A (so you'll have to measure transmit power separately and turn it down for profiling if you use the PPK2).
One of the major differentiators for these types of devices is the sample rate. If you're looking for a fast event, a device that samples at 10ksps or 100ksps might not capture it. The Joulescope samples at 2Msps and advertises a bandwidth of 300kHz. how fast and how large are the random current spikes you are trying to capture? There might be other approaches.
coppice:
I haven't used the joulescope or the ZS1100A, but they appear to be doing more or less the right thing for measuring total energy in bursty applications. The devil may be in the details, though. E.g. how well are they able to control things like ringing? Most tools, regardless of price, are pretty useless for these bursty loads, with huge dynamic range, where the high bursts are not the long term dominant energy usage. The other approach which works well is in some of the tools for the MSP430 family from TI. These feed energy into the supply in well controlled shots. If you count the shots you have an accurate energy measurement over a wide dynamic range. However, if you need to go up to multiple amps, the TI tools I know of will be overloaded. I do like that approach, though.
PlainName:
--- Quote ---where the high bursts are not the long term dominant energy usage
--- End quote ---
Depends on the application. I'm currently trying to sort a supply for a (third party) light sensor which connects via WiFi and goes through three AA batteries in a couple of days. I think the periodic WiFi connection, brief though it is, massively overwhelms the sleeping power draw.
Similarly, Bluetooth can be a bummer if, between connections, the kit is just kicking its heels waiting for something to connect. Just spacing out the advertising a bit can make a big difference in life.
Obviously, a slight change in background power draw can make a big difference because it's there all the time, but I would be surprised if it's a generalism that the bursts aren't dominant, at least with 'low power' kit.
coppice:
--- Quote from: PlainName on April 12, 2023, 10:28:44 pm ---
--- Quote ---where the high bursts are not the long term dominant energy usage
--- End quote ---
Depends on the application. I'm currently trying to sort a supply for a (third party) light sensor which connects via WiFi and goes through three AA batteries in a couple of days. I think the periodic WiFi connection, brief though it is, massively overwhelms the sleeping power draw.
Similarly, Bluetooth can be a bummer if, between connections, the kit is just kicking its heels waiting for something to connect. Just spacing out the advertising a bit can make a big difference in life.
Obviously, a slight change in background power draw can make a big difference because it's there all the time, but I would be surprised if it's a generalism that the bursts aren't dominant, at least with 'low power' kit.
--- End quote ---
If the high bursts dominate the power consumption there are numerous techniques that are effective to find them, and try to reduce them. However, you still need something like the joulescope to get an good assessment of what you battery consumption ends up looking like, without waiting for a real battery to wear out in real use.
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