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Astrohat - An open hardware RPi Hat for astronomy equipment

7 months 4 days ago
hy
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Astrohat - An open hardware RPi Hat for astronomy equipment #46343
If the goal is to power everything through this, I'd worry about the current draw of a mount while slewing. I'm pretty sure I've seen my Atlas Pro draw 4 or 5A, but just for a short while.

USB outputs might be nice, but I suppose one could just connect a powered USB hub to this hat.

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7 months 4 days ago
ppapadeas
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Astrohat - An open hardware RPi Hat for astronomy equipment #46344

hy wrote: I've seen my Atlas Pro draw 4 or 5A, but just for a short while.

That sounds a lot, my EQ6 fully loaded barely passes 2A while slewing. In any case 6A per channel should be OK as long as the neighboring channel (with which they share the load) is on less than 0.5A (they share 6.5A rating)

I plan to do some extensive testing on the loads to confirm the design assumptions.

hy wrote: USB outputs might be nice, but I suppose one could just connect a powered USB hub to this hat.


There is no way to get USBs through the GPIO header of the RPi, so that leaves you with the option to sacrifice one rpi port and put a hub. It makes little sense to integrate functionality in this hat unless it can be supplied through the internal GPIO header.

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7 months 4 days ago
ppapadeas
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Astrohat - An open hardware RPi Hat for astronomy equipment #46345

Ihoujin wrote: Amazing work.
As for GPS I am not very familiar with the TTL drone modules, are there options available that allow for an external antenna? I highly recommend supporting modules with a uFL socket for external antennas.


Since we are going for an aluminum case, the antenna needs to be external. It also allows for flexibility of placement for the whole system. Having an external thing though got me thinking.... why not get the GPS completely external (IC + Antenna) and thus save on internal space (since we are already packed) and also allow for a possible usage of the TTL (serial TX/RX, VCC, GND) port for something else (in case someone does not want the GPS). Such GPS modules are cheap and look like this . Makes sense?

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7 months 4 days ago 7 months 4 days ago by ppapadeas.
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Astrohat - An open hardware RPi Hat for astronomy equipment #46347
I pushed some changes on the repo and concatenated a bit the BOM in order to do some price calculations. Here is what we are looking at:

All the components I selected are high-grade ones. Automotive and Industrial grade capable of performing to extended temperature ranges (since it is highly important imho for our setups) and less prone to EMI. I did not "cut-corners" at any point during the design and component selection process. All in all if someone was to buy today all components for the board you would be looking at around 45 USD. PCB production would be around 5-10 USD depending on your source. (w/o shipping obviously).

Now those are prices for a *single* board, and without trying to make everything less expensive (e.g. searching for cheaper connectors, cheaper RTC, replacing some Caps with cheaper options etc).

Just to get an idea about how prices differ on 100x scale, if you were to produce 100 boards like this you would be at around 35 USD including assembly! (with a possibility to get a bit lower while still keeping quality). (still w/o shipping ;) )

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7 months 4 days ago
AstroNerd
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Astrohat - An open hardware RPi Hat for astronomy equipment #46350

ppapadeas wrote: I pushed some changes on the repo and concatenated a bit the BOM in order to do some price calculations. Here is what we are looking at:

All the components I selected are high-grade ones. Automotive and Industrial grade capable of performing to extended temperature ranges (since it is highly important imho for our setups) and less prone to EMI. I did not "cut-corners" at any point during the design and component selection process. All in all if someone was to buy today all components for the board you would be looking at around 45 USD. PCB production would be around 5-10 USD depending on your source. (w/o shipping obviously).

Now those are prices for a *single* board, and without trying to make everything less expensive (e.g. searching for cheaper connectors, cheaper RTC, replacing some Caps with cheaper options etc).

Just to get an idea about how prices differ on 100x scale, if you were to produce 100 boards like this you would be at around 35 USD including assembly! (with a possibility to get a bit lower while still keeping quality). (still w/o shipping ;) )


Well as far as I am concerned that is an absolute bargain, and I would pay double for it...mind you I am in the UK so I have all the import duties and taxes too.... :)

Stellarmate OS on Raspberry pi4b
Skywatcher EQ8 pro, on steel pier
Takahashi FSQ85 & Meade 8” SCT (de-forked)
Starlight Xpress SXVR H18, SXVR M25c, Lodestar x2 Guide Camera
Pegasus Ultimate Hub V2 for all USB & Power
Pegasus focus motors on both scopes

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7 months 4 days ago 7 months 4 days ago by El Corazon.
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Astrohat - An open hardware RPi Hat for astronomy equipment #46351

AstroNerd wrote: Whatever is decided, it needs to be able to have the option of cooling the rpi, as with the rpi4 it gets very hot..so would need the room for a fan or at the very least a large heatsink... :)



This cooler is definitely cutting it! Keeps my Pi4 at 45 C and below!

smile.amazon.com/gp/product/B07V7SS5BZ/r..._title?ie=UTF8&psc=1

Highly recommend, as long as you can 3D print your own case for it.



BTW, I would be happy to share the FreeCAD and STL files, if anyone wants them (and hopefully improve on them). They are not very elegant, but functional for my purposes.

Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set
Attachments:

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7 months 4 days ago 7 months 4 days ago by jerry.
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Astrohat - An open hardware RPi Hat for astronomy equipment #46352
Anyone able to guess if the hat alone would fit onto a Odroid-N2 without modification?

https://www.hardkernel.com/blog-2/odroid-n2/https://www.hardkernel.com/blog-2/odroid-n2/

120 MM Skywatcher Esprit on Celestron CGEM DX HC: GEM 5.29.7137 MC: 6.50 6.50,
ZWO ASI 224MC or QHY-5L-II-M for guiding,
Nikon Z7 8256 x 5504, 35.9 x 23.9mm 4.34 um pixel size.
1) StellarMate on RPI4
2) Kstars on Odroid-N2 on Ubuntu-mate 20.04 and
3) KStars on Astroberry on RPI3.

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7 months 4 days ago
AstroNerd
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Astrohat - An open hardware RPi Hat for astronomy equipment #46354

El Corazon wrote:

AstroNerd wrote: Whatever is decided, it needs to be able to have the option of cooling the rpi, as with the rpi4 it gets very hot..so would need the room for a fan or at the very least a large heatsink... :)



This cooler is definitely cutting it! Keeps my Pi4 at 45 C and below!

smile.amazon.com/gp/product/B07V7SS5BZ/r..._title?ie=UTF8&psc=1

Highly recommend, as long as you can 3D print your own case for it.



BTW, I would be happy to share the FreeCAD and STL files, if anyone wants them (and hopefully improve on them). They are not very elegant, but functional for my purposes.


All well and good but would not work on what this thread is about...... :)

Stellarmate OS on Raspberry pi4b
Skywatcher EQ8 pro, on steel pier
Takahashi FSQ85 & Meade 8” SCT (de-forked)
Starlight Xpress SXVR H18, SXVR M25c, Lodestar x2 Guide Camera
Pegasus Ultimate Hub V2 for all USB & Power
Pegasus focus motors on both scopes

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7 months 4 days ago 7 months 4 days ago by El Corazon.
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Astrohat - An open hardware RPi Hat for astronomy equipment #46355
"All well and good but would not work on what this thread is about"


I'm not so sure, it just might be possible. That's why I showed the image with my current cooling solution.

I agree that with the conventional HAT design, which sits directly on top of the Pi board this would not work. That would fatally interfere with the cooling, whichever way you try to cut it.

However, this tower is hands down THE BEST cooling solution for the Pi4 (check out Christopher Barnatt's video on this cooler and how it compares to other solutions:
)

So I thought it might be worth exploring at this early stage, whether the AstroHAT can be designed in a way that allows incorporating this top of the line cooler for the RPi4 into the assembly.

I just think that might be possible, all that is required is to add some GPIO connection extension adapters that allow it to be moved up above the cooler. The 3D designs can easily be modified to make a case that incorporates the HAT with the cooler sandwiched in between the HAT and the Pi4 board and forming essentially a wind tunnel the cooling air is being sucked through, thus cooling the Pi4 and the HAT at the same time.

Worst case scenario, one can just use a cable to connect the HAT to the PI4 board ( core-electronics.com.au/raspberry-pi-b-g...-cable-40-pin-6.html ), but having a solid GPIO extender of the correct length would be preferable. That must exists somewhere.

It may be sufficient to stack 2 of these connectors on top of each other to clear the tower: cnclablb.com/raspberry-pi-gpio-tall-header-2x20.html

I would LOVE to have that construction on my rig. At the moment, I have 3 power lines running up the rig, one for the 12V needed to run the mount and the dew strips, one to power the USB hub and one to power the RPi4. If I could replace that with a single power line running to the HAT/RPi4 and everything else being powered off that, that would be ideal.

Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set

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7 months 4 days ago
El Corazon
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Astrohat - An open hardware RPi Hat for astronomy equipment #46356
Adding to my last post, Pierros, if you think that would be feasible, then I would suggest including a ground and a +5V pin on the BOTTOM of the board, to allow for the direct connection of the tower cooling fan (without having to run the wires around the HAT board and connect them to the pins on top).

Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set

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7 months 4 days ago 7 months 4 days ago by Robomort.
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Astrohat - An open hardware RPi Hat for astronomy equipment #46360
Active cooling is probably not required.
The RPI foundation have recently released a new firmware for RPI4 with better thermal management.
There are passive cooled cases which rival active cooling now available.
Ambient temperature outside at night works to reduce heating.
Finally, active cooling adds bulk and complexity.

I'd like to add a vote for focus motor driver be added
locking or latched DC connectors would be icing on the cake

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7 months 4 days ago
El Corazon
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Astrohat - An open hardware RPi Hat for astronomy equipment #46366

Robomort wrote: Active cooling is probably not required.
The RPI foundation have recently released a new firmware for RPI4 with better thermal management.
There are passive cooled cases which rival active cooling now available.
Ambient temperature outside at night works to reduce heating.
Finally, active cooling adds bulk and complexity.


Maybe not required, but for most of the time that Pi4 runs at 30 degrees C at RT. That can only be good. It crashes far less than my also actively cooled Pi4, but that one only has a fan blowing down on the heatsink. That goes up to 70 degrees C, which is when it is being throttled. I suspect that's one reason why it crashes more often.

No matter, with the design Pierros has posted so far, I can make this work with my large active cooling fan.

Really looking forward to implementing this!

Best

Jo

Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set

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