HEQ5 mods

[etill (Elliot)]

Originally I modified this mount some time back with nema16 steppers and onstep, but lately I haven't been getting out to do anything due to the hassle of carrying everything out to the yard and the large number of cables and power cords I need to route and avoid tripping over.

I wanted to make something simple, with just one cable to plug in and also something I could pick up while assembled and move around, so my CGEM was out for that use case. I also thought it would be cool if I could squeeze the computer itself into the mount.

This is the first pass at that, its using an 8gb Pi 5 with the pimoroni nvme base and a 256gb nvme drive. Running the default Pi OS with kstars, phd2 and astap. I use tigerVNC to connect from my laptop or desktop via wireless.

Seems to work well enough to be usable, although I prefer Windows + NINA (I might see if a Radxa x4 fits since its an Intel based Pi format sbc).

The ribbon cable is the power and the UART connection to the Pi header, no USB adapter necessary. I also made a smaller version of the onstep MiniPCB and cut out all the auxiliary stuff I didn't need to make it easier to fit. It's not my design, I just took the onstep schematic and re-did it in kicad to remove everything that wasn't entirely necessary, shrink it down and got it made by jlcpcb once it was working.

The Pi power supply is a cheap buck converter from ali express, it claims 5v@5A but I've only measured 3A or so being drawn from it briefly. I have no suitable load to test it with right now and the Pi definitely complains at start up so according to the docs that will limit USB peripherals to 600ma. I think this may be related to not using USB-C with PD so the Pi doesn't actually know what is connected. I only have a guide camera (ZWO) drawing power from the Pi, the tests are with a Canon 60D on its own battery. Other than that its using a teensy 4.0 with onstepX and TMC5160s for the drivers. There is no web interface so for now the only way to configure it is with kstars/indi. The power supply is 24v@5A and is the only cable connected to the mount.

I'm also no designer so I built a model in fusion to fit the pi5 which is not all that pretty, but it fits quite well given I modeled it using photos of the original part set up as a canvas. The screw holes are about 1mm out and since it takes 10 hours to print I figured I'll wait until I make sure its a worthwhile exercise to make the change and reprint it.

Here's some pics and initial guiding data from the first tests. I was able to do pretty lengthy subs without much trouble (tested up to 300sec), but I didn't put a lot of effort into focusing and wasn't trying to capture any images. I haven't set up the flatener for this combo properly yet either.



I'm pretty happy so far, next step is to make some minor tweaks to align the case a bit better with the holes in the mount, and do a new belt drive cover with some cable management built into it.

[AstroViking (Steve)]

Now that is very clever! I like it a lot.

I take it that you now only have very short USB cable runs from the Pi5 to the mount and cameras? How do you go for powering the mount?

With regards to the belt drive cover with cable management, does this help at all?

https://www.thingiverse.com/thing:4673432

Cheers,
V.

[etill (Elliot)]

Thanks, that model would have been handy, I made a simple spacer in fusion by scanning the cover to get the outline.

I'll make (or buy) some custom length USB cables and make a new belt drive cover to include some cable management to keep things tidy next.

It's all powered by a single 24v supply. I don't normally use my Canon anymore so I may need to run the power supply for the QHY camera separately, but for now the Canon runs on its own battery and the ZWO is ok powered by the USB port on the Pi.

[AlexN]

Really cool! I like it!