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Astrohat - An open hardware RPi Hat for astronomy equipment

6 months 1 week ago
ppapadeas
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Astrohat - An open hardware RPi Hat for astronomy equipment #46373

jerry wrote: Well I actually have both already :)
I'm a complete novice with electronics, so this looks similar, but maybe not sufficiently so.


Electrically speaking they seem compatible. I wouldn't be worried about the signal levels and GND positions too much, but rather be extremely worried about the software side of things and how we can access this "Extra" functionality we are asking from pins.

I am really pushing the envelope with RPi4 alternative functions on pins and trying to squeeze out as much functionality as possible, such as i2C, 2x SPI, Serial TTL, many GPIOs and PWMs.. so yeah, it would have to involve some testing to verify compatibility, but it will not elect a new pope in the process of doing so ;)
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6 months 1 week ago
kookoo_gr
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Astrohat - An open hardware RPi Hat for astronomy equipment #46375
My 2 cents, i would prefer if one or a few of the 12v output ports could be adjusted from 5 to 15V. I power my equipment from a deep cycle battery and in order for my mount not to have the blinking LED which means it doesn't have sufficient voltage, and it affects guiding, and for my camera to perform with no issues i power my equipment with 13,5V. I still haven't see this feature in any power box which means i have to power the power box with 13,5v and then distribute those 13,5v via the power box to my equipment for proper functionality.

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6 months 1 week ago
El Corazon
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Astrohat - An open hardware RPi Hat for astronomy equipment #46378

ppapadeas wrote:

El Corazon wrote: 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).


Noted! I am all for leaving extra ports for things that might be useful in the future ;) Although I think that the cooling tower is a bit of an overkill as others said (due to latest developments on firmware and target environments). I will be adding a port of 5V+ and GND with a simple JST-XH connector just in case though ;)


With respect to target environment: the nights in Texas can be pretty toasty in summer - upwards of 30 degrees C.

Even with that cooling tower, the Pi4 will get pretty hot around here. It shut down on me a few times due to overheating even this late in summer before I had the tower.
As for the firmware making the Pi4 more efficient: will that work on the Pi running Ubuntu?

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6 months 1 week ago
knro
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Astrohat - An open hardware RPi Hat for astronomy equipment #46379

El Corazon wrote:

ppapadeas wrote:

El Corazon wrote: 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).


Noted! I am all for leaving extra ports for things that might be useful in the future ;) Although I think that the cooling tower is a bit of an overkill as others said (due to latest developments on firmware and target environments). I will be adding a port of 5V+ and GND with a simple JST-XH connector just in case though ;)


With respect to target environment: the nights in Texas can be pretty toasty in summer - upwards of 30 degrees C.

Even with that cooling tower, the Pi4 will get pretty hot around here. It shut down on me a few times due to overheating even this late in summer before I had the tower.
As for the firmware making the Pi4 more efficient: will that work on the Pi running Ubuntu?


That's an excellent point. Here it can reach 45C in the summer at night, so active cooling for RPI4 is absolutely necessary.

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6 months 1 week ago
ppapadeas
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Astrohat - An open hardware RPi Hat for astronomy equipment #46380

kookoo_gr wrote: My 2 cents, i would prefer if one or a few of the 12v output ports could be adjusted from 5 to 15V. I power my equipment from a deep cycle battery and in order for my mount not to have the blinking LED which means it doesn't have sufficient voltage, and it affects guiding, and for my camera to perform with no issues i power my equipment with 13,5V. I still haven't see this feature in any power box which means i have to power the power box with 13,5v and then distribute those 13,5v via the power box to my equipment for proper functionality.


Some clarifications. The design as it is right now will supply to the channels whatever is supplied as VIN. Another 2 channels (Dew heaters) are PWM adjusted and 1 channel is LDO adjusted to 6-(VIN-something small). VIN in theory can be up to 16V, although I should probably protect the circuit at around 14.8-15V. Having an adjustable output that can go beyond the VIN would require a buck-boost circuitry that complicates the design at this point. If this is deemed critical, I would be happy to take a pass though.

This is a diagram to make it easier for people to see the main features:


As for active cooling I hope that the 5V port would be OK for a fan, but we really need to think about the fan placement. Having the boards at hand will help with that :)
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6 months 1 week ago
Robomort
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Astrohat - An open hardware RPi Hat for astronomy equipment #46384
Explaining computers did a quick test last week.
.
I would say however the second device where the heatsinks sandwich the board is a bit of a designers wet dream since the lower half is the most expansive but is not really thermally connected to the board only at the screw lugs to the top.
I prefer the Kodi branded unit since it performed better and totally enclosed the board.
Neither of course are suitable for a two layer stack but give insight into what works best. Use that knowledge to find other similar but taller solutions which no doubt will be available now or in the near future.
Personally I am using the Rock Pi 4 running a DIY Stellarmate install. They have a solution to house their board and an second layer and SSD. Rock Pi 4 sensibly placed the SOC on the bottom of their board making heatsinking much easier.

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6 months 1 week ago 6 months 1 week ago by Robomort.
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Astrohat - An open hardware RPi Hat for astronomy equipment #46386
never mind I looked closer at the features and you have my request covered

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6 months 1 week ago
ppapadeas
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Astrohat - An open hardware RPi Hat for astronomy equipment #46392
Backside with some additional ports as requested:
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6 months 1 week ago
El Corazon
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Astrohat - An open hardware RPi Hat for astronomy equipment #46398

Robomort wrote: Explaining computers did a quick test last week.

.
I would say however the second device where the heatsinks sandwich the board is a bit of a designers wet dream since the lower half is the most expansive but is not really thermally connected to the board only at the screw lugs to the top.
I prefer the Kodi branded unit since it performed better and totally enclosed the board.
Neither of course are suitable for a two layer stack but give insight into what works best. Use that knowledge to find other similar but taller solutions which no doubt will be available now or in the near future.
Personally I am using the Rock Pi 4 running a DIY Stellarmate install. They have a solution to house their board and an second layer and SSD. Rock Pi 4 sensibly placed the SOC on the bottom of their board making heatsinking much easier.



I can confirm the numbers in the Explaining Computers Video for the ICE Tower. The ambient temperature at which I tested the cooling using a 10 min stress test and maxing out all 4 CPUs was 5 degrees lower than in the video. The maximum CPU temp was 38 C. That's with the September 10 firmware update and running Ubuntu MATE.

This is a serious active cooling solution made for the warmer climates.

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6 months 1 week ago 6 months 1 week ago by SmackAstro. Reason: cleaned up bullets
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Astrohat - An open hardware RPi Hat for astronomy equipment #46423
This looks fantastic!

Here's a pic of my Indi/Kstars RPi box, which I mount on top of my scope:



On the left side of the box as pictured is an Raspberry Pi 3B+ with an Adafruit motor hat. On the right side on top is a little Anderson power pole power distribution box and below a little breadboard with a circuit for a dew heater. The my RPi has the following interfaces:
  • 1x12V (or whatever-it's pass through) input (Anderson Powerpole) - For my setup, there is only one cable from the ground to my scope: 12V power. My goal is to minimize the number of cables running up my mount to my scope so I put the RPi on top of my mount. I power my mount from a separate power supply so there's no need to run power down from my RPi to the mount. I interface my RPi to the mount via bluetooth.
  • 3x12V (pass through) outputs (Anderson Powerpoles) - One of these powers my SBIG ST-8300M camera and another powers my RPi via a 12V to 5V 3A converter. I'd like to figure out a way to power the RPi internal to the project box but haven't done that yet.
  • 1x12V RCA jack driven by my little dew heater circuit.
  • 1x3.5mm jack for a humidity/temp sensor - Used to calculate the dew point for my dew heater. Can also use ambient temp for focuser temp compensation.
  • 1x3.5mm jack to read the OTA temp - Allows for closed loop temperature control of the dew heater. I've written a little python script for this.
  • 4xUSB ports of the RPi for my imaging camera, guide camera, GPS, and a 64GB thumb drive for images
  • 1xD-sub 9 connector for my focuser (driven by the Adafruit Motor Hat)

So I think you've got everything I've got and more except a separate temp sensor input for sensing the OTA temp and a focuser. Are there any left over GPIO pins so that an OTA temp sensor could be used? I think an Adafruit motor hat could be mounted on top of your board but it'd need to get 12V power somehow and the I2C address would need to be changed if your board is using I2C.

Great project.

Steve
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6 months 5 days ago
SmackAstro
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Astrohat - An open hardware RPi Hat for astronomy equipment #46431

ppapadeas wrote: 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.


For me, it's all about real estate on the top of my scope. Most focus controller boxes are quite big. I have a Microtouch controller but it was just too big to be mounted on the scope conveniently.

Steve

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6 months 5 days ago 6 months 4 days ago by Bart. Reason: add photo
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Astrohat - An open hardware RPi Hat for astronomy equipment #46458
Hi ppapadeas,

Great idea!
I had a similar idea, as follows:
A board with a microcontroller (Teensy 3.2) controlling two (at least) heaters and a motor focuser. Also on the board a LM2596 power converter to power the Pi and the microcontroller.
It measures the temperature right below the heaters (at the telescope) with thermistors so as to have an actual regulator. I intend to use a HDC1080 to measure ambient temperature and humidity.
I see two dew-controller modes: temperature tracking (with a few degrees offset to correct for discrepancies) or dew point tracking (again, with an offset).

For the focus motor, I think using the TMC2130 is great because the current can be regulated by SPI (forget about trimpots) and the possibility to use 'stallguard' as a sensorless homing feature. Then the focuser can start at the point it was used at the last time.
I would use the Teensy because it can have it's own firmware, and possibly also operate in a stand-alone fashion, using a cheap (or expensive, if that's your flavour) IR remote control for the focus and the heater controller.

Currently I have stripped the 'MyFocuserPro2' firmware and installed it on the teensy. It does communicate and everything so... great!
Only thing is, I've tried connect it directly to the UART of the Rpi 4 (enabling serial in raspi-config) but unfortunately it doesn't connect. Using a TTL-USB converter I can connect it.

A nice add-on would be to incorporate a RTC, or even use a GPS.

Cheers,
Bart

Edit: I've added a photo of what I'm working on at the moment.
Rpi4 connects with the mount via bluetooth. Only one cable goes to the telescope: 12V power.
And working on making a battery-pack counterweight.

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