Yes, I continue to use the Pi4. But I got my Pi4s before they had the chip shortage. If you are planning to buy one now, you pay double the price for an 8GB version (definitely get 8 GB) and at that price, it is no longer competitive to NUCs, I would say.
Perhaps a better alternative would be an 8-core OrangePi with 16GB RAM for $132 on Amazon plus cooler ($20). The downside there is that the Ubuntu image for it is not the generic US Ubuntu version, but a Chinese version. I am not certain whether that might throw an error when you are compiling kstars on it. Have not tried that. I am using it mainly as a mail and video server so far. It also sucks a lot more power. You need a 4A power supply to run the OrangePi.
I gave detailed instructions somewhere else here on how to install Ubuntu on the Pi4. It was pretty straightforward. In fact, now you can just download a complete image from the RaspberryPi.org website. Even simpler. After that, it is just a matter of installing kstars.
The main problem I have with kstars is that after updates often some of the drivers fail and I need to recompile everything from scratch. That can be a major pain, so NEVER update before an imaging session. You may just end up missing much of the night.
Hope this helps.
Depends on 1) your code (how many steps does it allow), 2) on the torque your stepper motor can deliver (if attached to the main axis, you will probably require microsteps to achieve precise focus resolution. Microstepping reduces the available torque and will likely result in missed steps, especially when the telescope is nearly vertical and has to lift the camera and everything attached to it, so I have my focuser (also controlled by Arduino) attached to the reducer axis to minimize the need for microstepping.
You should be able to do that using the internal WiFi on the mini-PC, but you can also use an external dongle to do it.
I have used either approach and both work. I usually use a dongle to create the external hotspot as a backup, just in case I get frozen out by my Pi4 on the internal network.
I have also used the travel router, but if you are out in the dark, that is just one more thing that consumes battery power.
All of these solutions work.
The network issue I found was mainly a problem with the onboard wireless. I put an external 1200 Mbs adapter on the powered hub and then everything is instantaneous from 60 ft away.
The compiling, yes, that does take a long time. But once it runs, downloading to the SSD and running Ekos can only be marginally better with the NUC. I see very little lag there.
I guess it's time to retire my old Cray 1. It was getting a little heavy for the rig, I have to admit. And it was sucking a lot of power.... kissing.png