|
No, no, no - I mean send a few scanlines to the pseudo-ram before dumping a whole screen (I said page) to the display. 10 scanlines * 640 * 4 bits would only be (6400/2) bytes worth of uController ram. The STM32F103C8T6 has 20kb and runs at 72mhz. Last year they were $3.something US - now about a tenner.  Heh heh - good thing I bought 5!
Kinda neat (but probably pointless here) that the the esp32 lets you memory-map the pseudo-ram and access it like it's on-chip ram.
I'd imagine a RaspberyPi Zero would make a potentially half decent brain for an e-reader - they're only 10 Australian pesos for 512MB and 1Ghz. 17 or so if you want the one with onboard wifi and blutooth.
You're one smart bunny. Love reading about your exploits
modified 17-Jul-21 1:48am.
|
|
|
|
|
For $10 I'll just get an ESP32 WROOM devkit. You can get the chip itself for like $2 but that's without all the supporting hardware to make it go + program it. They're dual core 240MhZ with like 300kB of RAM available and 4MB of flash. WROVERs with the extra PSRAM aren't that much more, but are a little bit harder to come by reliably.
The problem with a raspberry pi is they are power hungry as heck. It's a bit hamfisted for an e-reader. You may as well just run some EPUB reader software on a linux desktop over HDMI with it. The power saving from e-ink won't matter. I mean, if you really want to save on eye-strain get a nook because doing this with a raspberry pi is like going fishing with a battleship.
And thank you! I appreciate it when people let me know they enjoy my work. I'm getting an E-PUB reader working on a WROOM. Right now I'm neck deep in making a zip library that allows you to stream the contents directly out of the zip file without loading them into RAM or storing them in flash uncompressed (but you can if you want/need to). EPUBs are just zips renamed, so I'm treating the entire zip archive as its own little read-only filesystem with all the EPUB html and image content.  No RAM use - except for a small amount of temporary block buffer for the decompressing stream. My end goal is to get it running on a WROOM, and running quickly on a WROVER.
Real programmers use butterflies
|
|
|
|
|
 Oh wow, your analogy is killing me with laughter. "fishing with a battleship" he he he.
"It is a cheap battleship" he feebly replies.. 
Letting you know the tales of your adventures are fun reading are the least I could do.. You go gettem! Sounds like you're a long way through the task of beating those epubs into submission. Love it. 
|
|
|
|
|
If you use it for a color e reader do you need to worry that much about power?
It seems like a few physical switches would let the device be powered off most of the time.
Click a switch to advance to the next page, power on, page renders, power off. (Screen still displays)
Slow human reader will take seconds to read the page.
|
|
|
|
|
Powering an RPi off and on like that creates an issue, in that it runs an actual OS. Turning back on isn't instant. Sure it might be able to be done, but whatever can be saved in power on an RPi it still pales in comparison to the savings of using an ESP32 instead.
To err is human. Fortune favors the monsters.
|
|
|
|
|
DIV.JS[^]
What do you get when you cross a joke with a rhetorical question?
The metaphorical solid rear-end expulsions have impacted the metaphorical motorized bladed rotating air movement mechanism.
Do questions with multiple question marks annoy you???
|
|
|
|
|
Not clicking on it, what is it?
|
|
|
|
|
HTML, but only using DIVs.
What do you get when you cross a joke with a rhetorical question?
The metaphorical solid rear-end expulsions have impacted the metaphorical motorized bladed rotating air movement mechanism.
Do questions with multiple question marks annoy you???
|
|
|
|
|
I'm surprised that hasn't become the new rage.
|
|
|
|
|
but still ... it's a funny joke
|
|
|
|
|
Arbitrary-palette positional dithering algorithm[^]
I've been working on supporting color e-paper devices in IoT gadgets where the e-paper ranges from 2 to 7 colors that I've seen.
In order to allow you to load JPEG images onto these displays reasonably, some amount of dithering is extremely helpful, but I never thought it could be so involved.
Even if I never used it, this is an interesting read.
Real programmers use butterflies
|
|
|
|
|
|
I used to own that book.
Real programmers use butterflies
|
|
|
|
|
Ha!
I might have ripped the pages out quicker, had I known the code'd have been accessibly posted in the future. But as it was I must have scattered more than a few pages, crumpled up in individual wads then thrown into the bottom of a shipping box to serve as padding for those heavier X-mas gifts sent east ... through the years.
|
|
|
|
|
Very interesting!
I certainly learnt a few things about dithering that I didn't know before...
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
|
|
|
|
|
I use a variant of one his algorithms in my code, but it's not fast enough for me for the devices I want to target. Then again, 640x448x3bits is taxing for any IoT device, even without dithering and color matching. I'm not even sure if that screen is practical at all though and I won't know until it arrives. It could be that the Pi is the only thing I have that will run it.
Real programmers use butterflies
|
|
|
|
|
It works fantastic for HTML to markdown, even allowing you to specify which Markdown dialect to use.
CloudConvert[^]
I use it for maintaining my GFX lib documentation - i load my codeproject content into it and produce readmes for Github. It's a snap.
Real programmers use butterflies
|
|
|
|
|
Probably belongs here: Free Tools Discussion Boards[^] - this forum is mostly for  moments!
[edit]
You probably need to be careful with posts like this as well - it's a paid-for service with a free trial (25 per day), so some will consider it spam rather than a tool post.
[/edit]
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
I always post tools in the wrong section
*headdesk*
sorry.
Real programmers use butterflies
|
|
|
|
|
Online converters are so cool.
You can seemingly convert anything to anything today.
modified 6-Jun-21 19:01pm.
|
|
|
|
|
Not quite. If those tools converted between C, C++, C#, Java, and Python, this site would be spared a lot of "Questions" that are nothing but code dumps asking for precisely that!
|
|
|
|
|
Quote: Not quite. If those tools converted between C, C++, C#, Java, and Python, this site would be spared a lot of "Questions" that are nothing but code dumps asking for precisely that!
Get after it then.
|
|
|
|
|
Greg Utas wrote: this site would be spared a lot of "Questions" that are nothing but code dumps asking for precisely that!
I admire your optimism!
Given the number of questions posted which could be answered by typing the question into Google and reading the first result, I doubt such a site would have any impact on the people who post the "convert this code for me" questions here.
Even if Chris managed to integrate the converter into the QA form, auto-detect questions about converting code, and automatically offer them the converted code, I suspect the questions would still get posted. After all, you can't expect them to have the time to actually read things on screen - they're far too busy trying to cheat on homework for a course they're not fit to pass.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
|
|
|
|
|
Nice, thanks for the link.
The less you need, the more you have.
Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?
JaxCoder.com
|
|
|
|
|
I totally put it in the wrong place tho. Again. *hangs head in shame*
Still, I'm glad you found it helpful. I use it all the time.
Real programmers use butterflies
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
