Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Show HN: ePaper.js – Easily create an ePaper display using JavaScript and HTML

github.com

Post reply on HN
Print view View original

1–10 of 14 posts

Re: Show HN: ePaper.js – Easily create an ePaper display using JavaScript and HTML

#3

Post by sdfhbdf »

Looks very cool and promising.

I'm wondering what's the power draw for the Pi with this one since it "Loads index.html in a headless instance of Chromium, using Puppeteer". Isn't Puppeteer quite a power hungry process?

Would it run on Pi Zero with a battery attached and how long would it last with updates once a minute or once every 5 minutes?

I'm thinking about possible projects that would not have AC power all the time, maybe something solar powered for a dashboard outside.

Re: Show HN: ePaper.js – Easily create an ePaper display using JavaScript and HTML

#4

Post by lukehaas »

sdfhbdf wrote: post #3

Looks very cool and promising. I'm wondering what's the power draw for the Pi with this one since it "Loads index.html in a headless instance of Chromium, using Puppeteer". Isn't Puppeteer quite a power hungry process? Would it run on Pi Zero with a battery attached and how long would it last with updates once a minute or once every 5 minutes? I'm thinking about possible projects that would not have AC power all the…

I built something that's similar to what you're describing, here's an article about it: https://www.hackster.io/lukehaas/e-ink-display-for-daily-new...

It combines a Pi Zero with a 2000mAh lipo, updates every 6 hours and lasts for around 90 days per charge.

Re: Show HN: ePaper.js – Easily create an ePaper display using JavaScript and HTML

#5

Post by taf2 »

lukehaas wrote: post #4
sdfhbdf wrote: post #3

Looks very cool and promising. I'm wondering what's the power draw for the Pi with this one since it "Loads index.html in a headless instance of Chromium, using Puppeteer". Isn't Puppeteer quite a power hungry process? Would it run on Pi Zero with a battery attached and how long would it last with updates once a minute or once every 5 minutes? I'm thinking about possible projects that would not have AC power all the…

I built something that's similar to what you're describing, here's an article about it: https://www.hackster.io/lukehaas/e-ink-display-for-daily-new... It combines a Pi Zero with a 2000mAh lipo, updates every 6 hours and lasts for around 90 days per charge.

Thanks I like the idea of a git pull on boot up.

Re: Show HN: ePaper.js – Easily create an ePaper display using JavaScript and HTML

#7

Post by capableweb »

sdfhbdf wrote: post #3

Looks very cool and promising. I'm wondering what's the power draw for the Pi with this one since it "Loads index.html in a headless instance of Chromium, using Puppeteer". Isn't Puppeteer quite a power hungry process? Would it run on Pi Zero with a battery attached and how long would it last with updates once a minute or once every 5 minutes? I'm thinking about possible projects that would not have AC power all the…

Quick idea: even though Chromium (not Puppeteer) is quite power hungry, you only need to run it once every update period and then take a archive/dump of the output that gets fed to the screen, then use this cache copy while shutting down Chromium.

Re: Show HN: ePaper.js – Easily create an ePaper display using JavaScript and HTML

#8

Post by mekkkkkk »

Waterluvian wrote: post #6

When using my reader, sometimes mutations require a full screen invert. Sometimes stuff just seems to change trivially. What governs that? Is that done by the display or driver or higher level code?

The problem with e-ink is that redrawing pixels without cycling leads to ghosting after a few draws. Most displays automatically cycles the entire screen now and then to mitigate this. I guess it's up to software or firmware to detect when to do it.

Re: Show HN: ePaper.js – Easily create an ePaper display using JavaScript and HTML

#9

Post by leetbulb »

Waterluvian wrote: post #6

When using my reader, sometimes mutations require a full screen invert. Sometimes stuff just seems to change trivially. What governs that? Is that done by the display or driver or higher level code?

In my experience with Waveshare e-ink displays, it's up to the application when to perform a full or partial refresh. Generally after so many draws, ghosting begins to appear and so you perform a refresh.

Re: Show HN: ePaper.js – Easily create an ePaper display using JavaScript and HTML

#10

Post by robocollab »

sdfhbdf wrote: post #3

Looks very cool and promising. I'm wondering what's the power draw for the Pi with this one since it "Loads index.html in a headless instance of Chromium, using Puppeteer". Isn't Puppeteer quite a power hungry process? Would it run on Pi Zero with a battery attached and how long would it last with updates once a minute or once every 5 minutes? I'm thinking about possible projects that would not have AC power all the…

It would be pretty easy to modify the chain of command to have the backend start and stop the Chromium process. I haven't taken any detailed measurements, yet, but I'm guessing simple web pages like the example weather dashboard aren't too CPU intensive to render.
Post reply on HN