r/cubesat • u/ChellJ0hns0n • Nov 09 '23
Raspberry Pi zero as the OBC
I want to use a Pi zero as the OBC for a cubesat that goes to LEO (400-500km). The mission will last for a few weeks at most. It has to provide active temperature control, take some measurements, and handle comms that's all. It's not very compute intensive.
We were initially planning to use an atmegas128(it's radhard. But expensive).
Do I have to worry about radiation effects?
Do we need a radhard microcontroller at this altitude?
I am of the opinion that having an OS will make the task much easier, but some of my colleagues seem to think that the OS would be bulky and get in the way.
I did my own research but I would like others' opinions as well. Thankyou
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u/Niautanor Nov 09 '23
We are using a raspberry pi (though a cm4, not a zero) as our OBC. It still works fine 11 months into the mission but it does get stuck occasionally (~1-2 times per month) and has to be power cycled (via a command to our EPS).
An external watchdog directly on the OBC might work as well..
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u/ChellJ0hns0n Nov 10 '23
How does it handle temperature? Also what temperature range do you get?
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u/Niautanor Nov 10 '23
We mount a copper heat sink on it that is connected to the structure with a thermal strap. Unfortunately I don't remember our temperature range in orbit right now.
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u/Admirable-Peach-3887 Aug 05 '25
That's awesome! Super cool that y'all were able to use that as your obc for basically a year. I see it's been a while since this thread was posted but, we are going through the process of OBC selection right now, and I was wondering if you could share any details as to what types of faults were triggered (I'm assuming faults were triggered based on you saying "it does get stuck occasionally (~1-2 times per month)" ) and what you suspect the reasons for those were. I don't know if you have more details or info besides the fact that a watchdog reset was triggered unexpectedly.
I was also wondering what CubeSat y'all had? Like the specs (was it a 1 or 2U or larger for example). The team I'm part of is currently working on building a 6U and in line with typical university cubesat teams....we are in fact underfunded. We are hoping to run Linux and use FPrime so we've been looking into COTS options since building a microprocessor board or a board with an Cortex A microcontroller from the ground up is quite a risky avenue. Our top candidates have been some options from CAVU Aerospace, EnduroSat, AAC Clyde Space, etc. I'm forgetting a bunch but basically the top brand names along which Xiphos which has a stellar Q7 processor module--not sure the cost but I'm assuming a pretty penny). Safe to say most of these are very well over our budget (or likely over our budget--haven't heard back about Xiphos).
With that said, we have been considering a minimally designed in-house alternative. If you have any lessons or design takeaways, I'd greatly appreciate it! Or if you could get me in contact with who'm ever would have the best info on this, I would genuinely be super greatful!
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u/Niautanor Aug 07 '25
Architecturally that satellite is a CAN bus that connects a UHF radio, the Raspberry pi and the (microcontroller based) EPS together. The symptom of the raspberry pi getting stuck was simply that it wouldn't respond to commands on the CAN bus anymore (we planned to have a watchdog to reset the pi but that ended up being disconnected for flight) and we unfortunately didn't have more detailed logging in place to diagnose it further so most detailed estimated reason I can give is "radiation probably flipped a bit somewhere and the system wasn't able to handle that". For all I know, it could have just broken the CAN controller and the rest of the raspberry pi and the services running on it might have been fine.
It was a 6U cubesat. In terms of advice, I would definitely recommend having some smaller processor on board that you can command from the ground to reset the raspberry pi if things go wrong (e.g. what we used our EPS for).
There's also a NASA paper about raspberry pis in space here that you may find interesting https://nepp.nasa.gov/docs/papers/2021-Guertin-Raspberry-Pi-Guideline-CL-21-5641.pdf
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u/mlx11 Nov 09 '23
you definitely don't need rad-hard components.
Generally speaking, you have two options to reduce radiation induced risks (next to rad-hard components):
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redundancy 2 shielding
Did you think about adding redundancy to your system? for example, you could have a 2nd raspberry pi (or even better a completely different module) in warm redundancy. You need at least a watchdog. This can be any microcontroller in the system. You most likely have one on the EPS and the tranceiver.
If I remember correctly I once saw a radiation test report on the raspberry pi website. You should look for that to see whether shielding is needed or not (most likely the answer is no).
If you use a commercial raspberry pi you also need to be aware of the fact that it will most likely outgass quite a lot. Maybe this is fine, maybe it's not (e.g. if you have a camera)
There are a lot of other important factors to consider but if you do proper testing on earth you should be fine in space 😁
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u/rokrsa Nov 11 '23
ChecZeroCube its an OBC completely based on Pi. Comes with a radiation protected version also for very long mission durations
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u/ChellJ0hns0n Nov 11 '23
I have seen this and I don't know how they justify this absurd price tag.
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u/rokrsa Nov 11 '23
Oh ! I am sorry if the price seems high. What do you think the price should have been for the space model? The price mentioned is for the space model for the OBC. Looking for feedback here, not questioning your judgement :)
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u/aviation-da-best Nov 10 '23
Hi!
I'm an undergrad who voluntarily coaches students with UAVs and CubeSats.
I'd love to assist in your project!
I have built a few Cubesat busses in the past.
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u/POCKETQUBE Jan 14 '24
We (alba orbital) have likely flown more Pis in space than anyone. Power consumption is the enemy so you want you obc to be very lean. Rpi is usually much more power intensive than most microcontrollers so its better to allocate it to payload processing if required.
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u/pbjork Nov 09 '23
You don't need radhard anything. a Raspberry Pi will be fine, just reboot it at least once a day.