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User avatar
By adam.g
#207423
Hey guys,

I haven't been able to find any information regarding the current draws for the various Redboard Artemis boards (i.e. ATP, Nano, etc.). Would you be able to point me towards where I might be able to find what the operating and quiescent draws are for the three board variations?

Cheers,
Adam
User avatar
By TS-Mark
#207513
Hi Adam,

Your results are going to vary depending on what you have the processor doing and how you are powering it. I am going to ask around to see if we performed more thorough tests but in a quick test using a variable power supply at my desk, these are the results I have from powering both the RedBoard and ATP versions out of the box (running Blink) with 7V into the barrel jack connector:
  • RedBoard Artemis: ~11-13mA
  • Artemis ATP: ~17mA
The current draw when powering via USB will be lower than these results since you are bypassing the variable regulator for the barrel jack input.

The Nano is a bit different since it does not use the LM117 regulator and also has the battery charging circuit included. In my testing with 5V applied to VIN the Nano was consuming ~6-7mA and ~4mA with 3.3V provided directly to the 3.3V pin (again while running Blink).

Finally, if you just want to measure the draw of the Artemis module on its own, you can sever the MEAS jumper on either the RedBoard or ATP versions (the Nano does not have this jumper) and then solder wire or headers to the pins next to that jumper to isolate power to the Artemis module and measure with an ammeter/multimeter.
User avatar
By adam.g
#207655
Hi Mark,

Thanks for your reply. I've since picked up Redboard Artemis Nano and have conducted some tests to determine the current draw under varying conditions. The tests involved uploading the Blink program and observing the current draw when the LED was OFF using a Fluke 287. I also made use of the Ambiq HAL & SparkFun BSP functions to attempt to place the board in a deep sleep (e.g. am_hal_sysctrl_sleep(AM_HAL_SYSCTRL_SLEEP_DEEP);). I've included the results of my tests below:

3.3V @ VIN
Awake: 2.8 mA
Sleep: 2.35 mA

5V @ VIN
Awake: 2.35 mA
Sleep: 1.89 mA

3.7V LiPo (4.2V) @ VBAT
Awake: 2.35 mA
Sleep: 1.88 mA

I was disappointed to see how high the quiescent draw of the board was, especially since the Artemis itself has a "1μA deep sleep mode (BLE Off) with RTC at 3.3V". Looking at the schematic, it appears that the biggest offender is the PWR LED, which is always ON. I measured a 1.64V voltage drop across the LED, which I believe gives us a constant 1.66 mA current draw across the 1K Ohm resistor. The AP2112 LDO is also going to contribute 55 uA to the quiescent draw, but I feel like there's other offenders I haven't discovered as of yet (I'm looking at you: MCP73831).

I'm really keen to find a low quiescent draw QWIIC board, but I'm thinking the Artemis Nano may not be the one. Happy to hear if you've got any suggestions of other boards or how to decrease the quiescent draw even further!

Cheers,
Adam
User avatar
By TS-Mark
#207681
Hi again Adam,

Thanks for taking the time to do some really solid measurements here to get a good idea of what the Artemis Nano will draw in different situations. We really do appreciate your work here along with your feedback about the quiescent current draw of the Artemis Development Boards.

The Nano was never designed with true low-power operation in mind, unfortunately, but, if you want to further try and reduce the current draw for your Artemis Nano, you are on the right track with disabling/removing the power LED and investigating what type of current the MCP73831 pulls without a battery attached. That should be a pretty low current draw but it's worth checking. One other note is to try powering with 3.3V directly to the 3.3V pins since that will bypass the AP2112K 3.3V regulator. You really should not see too much being drawn by that with 3.3V applied to Vin but it's another component that will add to the total current draw of the board. The other component to look at is the microphone. Disabling power to that will definitely help with power conservation.

As of right now, the best option we have for a dev board that has a Qwiic connector and is relatively low power is the SparkFun Edge. We do have a new version of that with the full Artemis module onboard slated to release soon so keep an eye out for that but as far as I know, this will still have some issues for a true low-power solution since the mics and accelerometer are large current sinks (relatively speaking) and there is no easy way to disable them with this version.

Finally, I do want to again thank you for your feedback regarding the Artemis module and how we do not have a low-power option to truly showcase the abilities of the Artemis module. We have taken that along with other users' input into consideration and actively working on another board that will allow some user-configurable options to truly get a low-power development board using Artemis.