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Current draw from various boards
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Current draw from various boards

by Rcayot on Sat Feb 20, 2021 8:45 am

Hello,
I am building an outdoor weather sensing system that I intend to power by solar panel/charger. I was going to try to use my Pi Zero W, but I have found that it gobbles up power!

I then tried to find the power consumption information on various boards from Adafruit, and I cannot find that information.

I would need to know the current draw from the microcontroller board ( say an itsybitsy M4) plus a wifi module, or a wifi capable board.

Please help me find that information.

Thanks in advance,
Roger

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Re: Current draw from various boards

by blnkjns on Sat Feb 20, 2021 10:52 am

Ditch the WIFI, that is the real power gobbler. You're better off using BLE, which can do longer ranges outdoor compared to WiFi. Or LoRa.
BLE has it in the name: Bluetooth Low Energy! For low data rates it consumes very little energy.
Nice board with everything built in is the micro:bit. The older is probably a little less hungry as it is clocked on 16Mhz (more than enough for your needs), but the new one has a more modern chip and BLE 5.0, which makes the Bluetooth a tad better (range and power consumption). Maybe you could underclock the micro:bit v2.

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Re: Current draw from various boards

by adafruit_support_bill on Sat Feb 20, 2021 11:04 am

Most modern microcontrollers have fairly sophisticated power management capabilities. The good news is that they can operate very efficiently. The inconvenient news is that there is no simple number that defines their power requirements. It depends mostly on what you program it to do.

By disabling unused parts of the processor and putting it to sleep between transmit cycles you can conserve even more power.

If you search the forums you should find several threads regarding low-power weather stations.

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Re: Current draw from various boards

by Rcayot on Sat Feb 20, 2021 3:16 pm

thanks for the ideas.

I am using wifi because, while I have gotten BLE to work using the 'controller' function, I have yet to see an applicable data streaming example that would help me. I know there are a bunch of 'learn' modules on BLE, but as far as code examples, there are few.

If you can think of any BLE examples with code, where a sensor is sending data to BLE, I would appreciate it.

I have an itsybitsy nRF82540 that works well using Circuitpython and the adafruit BLE library, but only in 'controller' mode.

I could use MQtt, or UART but don't know how.

I already have the example with wifi working, but on a Pi Zero.

Roger

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Re: Current draw from various boards

by 42volts on Mon Feb 22, 2021 5:26 pm

I was trying to do a low power project using adafruit hardware once a couple of years ago. The goal was to use a Nordic nRF52840 on a coin cell, and had to run for at least a couple of years. Unfortunately, adafruit doesn't put a lot of effort into the power consumption side of things, so while the nRF was capable of an average current draw of under 5 microamps while meeting my project's needs, the adafruit boards for it were running something like 1000 times that. I ended up abandoning the idea of using adafruit hardware for prototyping and went with a nordic dongle; https://www.nordicsemi.com/Software-and ... 840-Dongle

Now given that the rpi was ever even remotely under consideration, I would assume that you have a considerably higher power budget than single-digit microamps, so adafruit hardware may be suitable for you.

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Re: Current draw from various boards

by 42volts on Mon Feb 22, 2021 5:31 pm

Rcayot wrote:If you can think of any BLE examples with code, where a sensor is sending data to BLE, I would appreciate it.


You should be able to find a suitable example here; https://github.com/zephyrproject-rtos/z ... /bluetooth
Maybe the "peripheral_esp" example? Basically, it sends sensor data (temperature, humidity, pressure).

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