When I worked in the new main panel, I did rewire the INA219 so that the charge port is on the “output” side of it. Initially I thought feeding power in from the output side would damage it. It can actually read the reverse current though. Granted It can only take so much current, but the charger won’t charge the battery at that high of a current, well it “should” never. The fuse is inline still, so hopefully it would blow before the INA219 was damaged if something goes wrong.
I ordered a Raspberry PI Keyboard when I placed an order at Digikey as they were in stock and not a horrible price. I knew they were “close” to the same case as the Pi400. Also the Pi500 “looks” to be the same shape of case. I was going to by a Pi500, but decided against it at this time. Below you can see the Pi Keyboard fits in the plate. You can see it is not a perfect fit, but it this is the second Revision print. I knew it wouldn’t fit perfectly into it, as the Pi400 didn’t either. With the third revision of the plate the Pi400 fits much better, and therefore the Pi Keyboard will too, it does show the dimensions are the same, the port placement is good too. Based on that, I do expect the Pi500 will fit as well. The Pi500 would be a better fit than say a Pi5 due to heat, but the Pi500 doesn’t have the PCI Express support right? It would be best powered with some other power solution though, as I believe at 5V it is throttled. I guess a Pi3 (or earlier) or a Zero 2 or such could be used in conjunction with the Pi Keyboard. You could also use another 5V Powered SBC..
Speaking of the Third revision of the main panel, below are some pictures of the third print of the panel. You can see I installed the Magnets, and those yellow rectangles are the back side of some 2 sided adhesive on metal plates. The plates then had the backing paper taken off and were attached to the Pi400. It does fit the Pi400 better now.
You can see the bottom of the panel, that is the Revision 2 print before I removed the battery, speakers and touch pad while I was switching over to the new print. The last picture above is the internal below the plate. From the bottom the Revision 2 and Revision 3 print are the same. I did not install the threaded inserts around the speakers, and the two below the keyboard opposite of the battery compartment as none of those are used. It is a bit sloppy and messy. The 5V Regulator on the left is stuck down with velcro, the RTC as well, and the current and voltage sensor. The 2.5″ SSD is just loose as well as the fuse holder. The cables plug into the Pi400 ports, except the Battery power connectors.
That photo was before rewiring the battery connections and INA219. Doing that, connects the Charge port to the Main Power switch instead of only to the battery. That does mean there is no fuse between the 5V Regulator and Monitor. It though does mean that the charger port power goes into the INA219’s “output” side, and that it can now read the Negative Current, or the fact that it is charging. It also means that the Charging into the battery now is fused as the fuse is between the INA219 and the Battery. So the fuse is protecting the charging and discharging of the battery. Where previously it was only protecting the discharging of the battery.
Something I had found building this project up is that while the new switches look just like 30+ year old switches, the plastic they are made with is not very heat resistant. It melts easily. The terminals on these switches are big and thick just like the old switches, and they take some heat, and reworking the wiring is very likely to melt and destroy the switch. I had to replace a couple of them when I tried to redo the wiring on them as they melted apart. The old switches where hard and brittle almost like Bakelite? I almost used some vintage switches, but I didn’t have enough of them as I found some I had were cracked and not usable. They also had a different thread type, meaning I couldn’t use the Black Rubbery caps.
Below are some photos of the Revision 3 panel. If you look at the other photos of the Revision 2 print of the main panel, the Pi400 generally has some of the “raspberry” color showing on the left side, because it is not properly seated in the 3d print. Below you can see that only the upper White portion of the Pi400 is above the 3d printed panel. It is also much more difficult to remove as I can’t get a grip on it, because the seam between the upper and lower panel can’t be reached. It is down in deeper and does have the small metal plates and magnets under it.
I found the RTC module has a Red LED on it, that made me wonder why such a thing would be on it. I might look at removing it. You can see the LCD backlight is lighting up the inside of the upper panel, because there is no light blocking in there. I thought of putting in a black coating or cloth on the inside of the top, as the top is largely exposed metal. That may lower brightness of the screen if enough of it is actually reflecting back toward the lcd. I am not sure what difference if any would be noticeable.
I have worked with the Meshtastic LoRa radio setup some. I am still not happy with how it is operating. I did find a few things, one is an installer script utility/gui to install Meshtastic D on the Pi. That helps verify that it is all installed properly. I also tried out MeshSense on it, which is Beta on Pi. This is the only LoRa device I can currently use MeshSense on. I ran it for a long time the other week, and it seemed to work fine. I ran it yesterday and it kept cutting out after less than an hour I stopped getting any thing come in on it, and my other Meshtastic node showed it had went offline.
Muldrf's Hobbytronic 