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0 pointssho_hn3y ago0 comments

For the most part I've found that RaspPis are over-dimensioned for many projects I'm inclined to do, for example around the house, and have switched to much more readily-available and cheaper ESP32 and STM32 boards.

I do have a RasPi in use that runs some heavier software like a Hue bridge emulator written in Python (diyHue), and for some of my projects I now have that Pi do more intensive computation centrally and then just dispatch results to esp32s.

I'm currently building one of those refresh-once-a-day framed e-ink "newspaper on the wall" projects. In the picture frame I just have the panel, an IT8951 display controller and an esp32, all running off a LiPo pouch, mostly in deep sleep. The RSS scraping and pdflatex+ghostscript pipeline to produce the image is running on the central Pi in this.

A single Pi may be all you need if your projects live on a network!

0 pointssho_hn3y ago0 comments

A single Pi may be all you need if your projects live on a network!

0 comments

7 comments · 3 top-level

knodi1233y ago· 2 in thread

How much time can you get off a lipo pouch?

If it's "on the wall", why isn't it powered by an ac adapter?

sho_hnOP3y ago

> How much time can you get off a lipo pouch?

Time will tell, but I'm hoping for at least a couple of months on a 1100 mAh. Napkin calculations had me at 6-7 months.

It's e-ink, so I can shut down the entire display and controller after the refresh, and the ESP32 is in deep sleep until it wakes up on timer and performs a network fetch and display update, then back to sleep.

> If it's "on the wall", why isn't it powered by an ac adapter?

Effort :-) It's a picture frame on a wall, I don't want to have an externally visible cable going into it and burying a cable in the wall is more work than all the rest of it.

knodi1233y ago

Wow, I'm not used to thinking of batteries in those terms. If you hit 3 months, you deserve to crack a bottle of champagne, that's a really impressive bit of engineering. Although now that I think about it, smoke detectors have been lasting a year on a 9-volt for all my life, so maybe I'm just short-sighted. :-)

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dividedbyzero3y ago· 2 in thread

What panel are you using?

sho_hnOP3y ago

This one: https://www.waveshare.com/product/displays/e-paper/epaper-1/...

13.3", the largest I could afford :-)

aliqot3y ago

That's so cool. Did you build this from instructions somewhere or just using your imagination and seeing what works? Perhaps a build log article maybe?

1 more reply

madaxe_again3y ago

Yeah, I have a single 4b doing everything from openhab to shinobi to LoRA bridging, MQTT brokering, VPN termination, DNS, routing, pretty much anything where I need a Linux box to do a thing - we live off grid, so having a handy utility server that uses very little power is dead handy.

Plans to get another, as some redundancy would be good and it strains transcoding video, but you can pile a surprising amount onto one.

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