Here's part two of this project.

Right now, I'm using this old raspberry pi to test dimensions.
Before this project is over, I'm going to get a Pi model 3 or 4. Those have built in wifi and run faster.
(This unit is an original Raspberry Pi model B. I've been using it since 2012 for various things.)

I have this fancy Waveshare screen. I spent a little extra money to get a name brand screen, hoping it will last longer than a knockoff.

Everything sandwiches together just like on the original chumby!

I need to dremel off the screw pegs on the back side of the screen housing. The new screen is just a little too wide to fit between them. I searched for a screen that was the same size as the chumby's stock screen, but came up empty.

The screen isn't a perfect fit. Once those pegs are gone inside the unit, I'll have a better idea of how it'll look.

Looks like a cool project! Please keep us posted on your progress

You have a typo, it should be "IHTFP".

https://en.wikipedia.org/wiki/Hacks_at_ … Technology

This is incredible. Keep us posted on progress! I have a pi 3b sitting here waiting to be used with a damaged Infocast 3.5

Here's a little update.

I got the screen positioned in the bezel. I had to scrape away all of the internal screw holes and spacers, but those aren't useful anymore since they only lined up with the original chumby board screw holes.

The ethernet ports are getting in the way, so the edge of the case also needs trimmed. That's going to happen later once I decide on a version of the raspberry pi to use in the build.

Luckily, the new screen is exactly the same width as the legit chumby screen. It's not as tall as the original, but I'm probably not going to worry about that.

The software is probably going to be stock raspbian. There aren't any great interfaces for a screen this small.

If it's complete unusable due to the tiny screen, I'm not sure what I'm going to do. I already have plans for a v2 that should solve the screen issue, but I want to finish this one using the hardware that I have.

My other idea is to use emteria, which is an android distribution. That's going to require a little more effort. It will run fine on the Pi, but I'll need to load the touchscreen drivers as a module, which I have never done before.

If the raspbian isn't useful at this resolution, I won't even bother pursuing that. If I can't get emteria running, I'll go straight to plan B.

Don't quite know what plan B is yet, but I'm working on it.

One of the problems with these small RPi displays is that they're very slow - they typically use SPI, so data transfer rate is quite limited.  I ran some tests running the chumby middleware stack on them and although the main processor of the Pi is obviously much, much faster than a chumby, the display was much slower, so there was a lot of tearing, etc.

There is a nice display made by Pimoroni that uses most of the GPIOs to create a faster, more parallel way to send data to the display, but it's quite a bit more expensive than the SPI displays.

The official 7" display is plenty fast, because it's directly supported by the GPU, as is the HDMI port.  I asked the Pi folks if they were planning on making a small display that used the display port, and at the time they felt there wasn't enough of a market, that between HDMI for static devices and the 7" display  for portability, they had the market adequately covered.  Personally, I think a fast 3.5" capacitive display using the built-in display port would be a nice addition to the Pi family.

My only real complaint about the official 7" display is that the pixels aren't square - the pixel density varies by direction.  The Sony dash display had a similar issue but was somewhat addressed at the cost of some blur.

I've decided to go in a little different direction with this. I have a bunch of new parts coming in the mail. First prototype should be done by Saturday.

Once I actually have a product, I'll post a video explaining everything. My preliminary work is quite promising!

In the meantime, did you know your chumby has a magnet inside of it? It exactly opposite the charm holder.

Can you post anymore details on the pi software side?

Ok, let me get some stuff together and I'll make a new topic with some instructions and the necessary files. Give me about a week.

In a nutshell, it has four html files that run. A file with rotating data, a clock, a main page that combines the two, and a night clock. I am also using CRON for the schedule. the main page loads the clock/rotator which runs all day, then cron kills the page and loads the night clock and maximizes the window. It does the reverse in the morning.
The rotator page loads pages or pictures from the net or the local drive (if you want a slideshow).
It all runs on raspbian/chromium browser.

Still working on the manual nightmode button....I am really close.....

That's brilliant. I never considered using a full screen browser window as the interface.

Can the web browser read the state of the GPIO pins?