1 (edited by pstrick2 2019-11-20 20:17:19)

Topic: Chumbi -- raspberry pi in a chumby classic

I figured I would start posting my progress here of cramming a Raspberry Pi into a chumby classic.
The project is in the early stages, but it looks pretty straightforward.
I have some big goals, but I expect moderate success with this.

The Teardown:

Here's the Chumby I bought from a member of this forum. The screen is completely destroyed, which is why I am comfortable giving this a shot. No chumbys were harmed in the making of this project.


Glamour shots of the chumby:
The chumby that sits on my bedside table is a model 3.8, while this is a v3.7.
The place where charms attach is different, as are the stamps on the bottom of the unit. I know this unit doesn't have a variable backlight either, though I obviously have no way to test that here.


Overall, not a bad looking unit.

Here's a chumby with its face peeled off. The screen was easy to remove. The rubber came off with minimal effort. If I do this again, I'll make a video.

The cable runs to the back of the unit and connect all the ports and speakers to the mainboard.

Speaking of, here's there heart of the chumby:
The main board is attached to the back of the screen, with a wifi daughter board sitting behind that.
I have no idea why this wifi card is placed like this. Seems like the USB dongle could just be plugged into the main board. Maybe the reception was bad with the adapter next to the rest of the electronics?





Here's the unit with all the stuffing removed. I was surprised to find that the bend switch was just a normal switch with a bent metal tongue. Not what I expected.


There are 4 screws holding the speakers and ports onto the rubber on the back of the unit. I tried to take a picture, but there wasn't much light deep in the Chumby's guts.

I pulled out the daughter card that is mounted between the speakers. It's an interesting little unit. Looks like someone had a good time when designing these boards.




I have high hopes for this daughter card. I don't see any sort of control board on the card, so I'm hoping everything is directly wired to that daughter board.
I'm certain those speakers can be reused, but I'm also hoping I can splice the ribbon cable with a USB cable extender and use the USB ports on the daughterboard as extensions for the ports on the raspberry pi.
I don't know if the headphone jack or power jack can be reused, but I'm looking into it. Once I find my multimeter, I can find where everything goes and make some decisions.

Re: Chumbi -- raspberry pi in a chumby classic

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.


Re: Chumbi -- raspberry pi in a chumby classic

Looks like a lot of fun.

Tar, feathers, congress. Some assembly required.

Re: Chumbi -- raspberry pi in a chumby classic

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

Owner of three Chumby One, an Insignia 3.5, and Sony Dash C10. A tinkerer at heart and IT manager by trade.

5 (edited by pstrick2 2019-12-01 12:15:13)

Re: Chumbi -- raspberry pi in a chumby classic

Here's a little digging I did on the daughterboard.

As I suspected, everything is connected directly to that 26 pin connector. This means I can reuse everything in my new build!

With a simple continuity test, I was able to figure out the following connections:


The connector that says "battery" is a little strange. This revision did not support a 9 volt battery. There was a 9v connector inside the unit, but it had a piece of plastic glued over it that said "Battery no supported. See chumby.com/help"

There seem to be two ground pins, which I noted on the barrel plug.

I don't know how headphone jacks work. The two connectors on the back of the plug are connected to both pins 10 and 23. I'll have to do more research.

The power switch on the back has three legs. When pressed, it bridges the connecting between the pins.

The biggest issue is with the USB ports. I'll have to reassemble the chumby and test the connections when they are live. I'm confident in the way I labelled them, but don't want to take any chances.

Oh, yeah. If you look at the back of the Daughter board, you can see 'ITHFP' in the lower left corner. (it's obscured in the labeled image, but you can see in in the first post.) That's a call back to Bunnie's alma mater, MIT. (Google it.)

Re: Chumbi -- raspberry pi in a chumby classic

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

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