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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Astrohat - An open hardware RPi Hat for astronomy equipment

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Looks great. I was trying to consider what I have that might draw more than 3 amps. Maybe my camera at 100% cooling or a dew heater?

I think I need to test it and find out. :)
4 years 4 months ago #46275

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The channels in pairs can draw 6A combined. Which means that in theory you could get e.g 5A in Channel A and then 1A in Channel B and still be OK. I guess we will have to make this somehow visible on the interface too (and on the case?)
4 years 4 months ago #46279

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Wonderful idea!

I was wondering if something was available the other night as I came inside with my arms full of wires, cables, and power adapters for the various bits and pieces attached to my scope. Good luck on this!
4 years 4 months ago #46287

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I am adding a connector exposing a serial port, for another peripheral. GPS is the prime candidate for that since there are many cheap serial (TTL) modules out there. (thanks to drone racing! :P)

Any other ideas? Features you would like to see?
4 years 4 months ago #46293

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Actually I think you have covered pretty much all of what is sneezed on a typical imaging set up, and what you would get on a commercial power hub, apart from maybe an output for a motor focuser..but with the units around now that have the controller built in to the motor housing, it’s probably not needed....
So all good, I would certainly buy one if you produced a few, along with a case for the lot... :)
4 years 4 months ago #46298

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Oh this is promising. A dedicated astronomy HAT. Love it.
I ended up cramming GPS, RTC, Motor controller and a power supply board (Docker Pi) within my case. So if there is anything worth adding, I would say GPS, RTC and 5V@4A power to the Pi is what's most useful.
For motor control I installed the Adafruit motor HAT. But the Pololu A4988 controller is arguably better with higher supported PWM frequencies.
4 years 4 months ago #46306
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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... :)
4 years 4 months ago #46324

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Thanks for the suggestions!

I just pushed a new version on the repository and added the following:
- An external TTL connector for connecting a GPS module
- A RTC complete with battery
(here is a pic with the connector and the RTC)


As for the rpi supply the board has a 5V@3A power supply integrated.
Motor control is a bit of an overkill at this point imho, mainly because most of the newer focusers have the control integrated, but please let me know if you feel this is a showstopper.

@AstroNerd: regarding cooling, indeed it will be an issue. we will have to see once the first dev board arrives how we can accommodate a fan or a heatsink.
The following user(s) said Thank You: AstroNerd
Last edit: 4 years 4 months ago by Pierros Papadeas.
4 years 4 months ago #46331
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Amazing work.
Motor control is by no means a show stopper and certainly exceedingly difficult to include, that's why I didn't list it among the most useful features. However spare 5V and 12V headers with reasonable amperage supply and some filtering to power a stepper motor board one might add would be appreciated. I had to use a mini-buck converter stuck beneath the power board to power mine, (Follow the white power wires in my previous image).

As for anything else. Maybe an on/off switch. For cooling the Pi4, a 30mm fan is quite adequate in my experience, but I also have heat sinks installed. Regrettably it would monopolize a lot of space. 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.
4 years 4 months ago #46339

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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.
4 years 4 months ago #46343

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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.

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.
4 years 4 months ago #46344

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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?
4 years 4 months ago #46345

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