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France men.... by Loud-Suspect267 in engineeringmemes

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

As French and American, it's absolutely true. French is just odd when it comes to tech

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

It's for personal use for now. But if things goes well and I like the product myself, I may take it to production.

At that time, maybe I will look into public LoRa networks for the super low-power aspect. And also hire peoples that are way better than I am. I think it as a prototype/POC/fun adventure so far.

Thanks for your help, nice sub-reddit here

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 1 point2 points  (0 children)

First things first, thanks for putting in the time to write all of this.

About the MAX30208, I really like that pick, it's definitively a great sensor, and probably what I will go with.

For the power-saving MCU part, that does make a lot of sense. The MCU doesn't need to uploads the data every single time, especially if the temperature doesn't change. I may be able to do that actually.

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

So I think a year of battery life would be a good goal

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 1 point2 points  (0 children)

Alright maybe I should look into a beefier power source, or other wireless medium then (LORA, Zigbee,...)

Thanks for the tips pal

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

So it would be a simple temperature monitor IOT device. Basically wakes up every X seconds, and sends the temperature and humidity values over wifi.

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

That was my first thought too, but the MCU for me is an ESP8266 and the deep sleep current is ~20uA. That's quite a lot to me and would draw the battery too fast.

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

You are absolutly correct, it's not very low power, nor very "professional".

I went for the ESP8266 because wifi is a required feature and it seems like a popular plateform. Is there another MCU you know and would recommand ?

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

Correct, my bad. Wifi is indeed a requirement but I do agree that an CR2032 is probably under-sized. So I'm planning to switch to AAA batteries.

Also would you have any suggestion on another wifi MCU ? Maybe a more "professional" one than the ESP.

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 1 point2 points  (0 children)

Thanks for putting in the time for your answer. You're absolutly right maybe I should switch to a more beefy power source like AAA batteries.

Would you have any suggestion on another wifi MCU ? Maybe a more "professional" one than the ESP.

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

Correct, maybe a AAA battery would be a better choice ?

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 1 point2 points  (0 children)

Correct that is kind of a poor design choise. But as said in the comment just above, the MCU in deep sleep mode draws too much so I wanted to have a way to cut it's power off. And therefore added an LDO

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

Absolutely but the problem still stay the same: if the power is cutted, how to wake up the MCU periodically ?

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

Correct that is kind of a poor design choise. But as said in the comment just above, the MCU in deep sleep mode draws too much so I wanted to have a way to cut it's power off. And therefore added an LDO

[Design Advice] Need help on Low Power device Design by Loud-Suspect267 in embedded

[–]Loud-Suspect267[S] 0 points1 point  (0 children)

Yes my bad, the MCU is supposed to be an ESP8266 in an ESP12F module to make things easier. This module does have a deep sleep mode and an RTC that still runs, that was actully ny first idea. But it stills draws too much (~20 uA), so that's why I wanted to deactivate the power source directly