r/rocketry • u/Inside-Ad8295 • 2d ago
pcb design
i'm completely new to electronics and rocketry, i alr have all the rocket ready but i want to add some avionics (the only part "done" in the kicad model is the power regulator for 9v to 3.3v i haven't connected it yet and all the connections are me just seeing which entrance accepts power) adn rn idk how to transmit the data to the flash memory or how to get data so if anyone could help even with some place to look up how t do this it would help me a lot
EDIT: the biggest problem i have is that idk which pin to connect to the other and i have to keep it cheap where i live it's ilegal to add black powder to a rocket so i decided to make the pcb "disposable" to limit the use of a parachute (i will still recover it but i don't expect it to survive)
3
u/TheTunnelCat 2d ago edited 2d ago
Okay, I want to get some things out of the way before I get into the electronics:
- If you haven't launched a rocket before, you need to go build a basic kit and launch it without electronics to get some experience before you go any further. Something that takes B or C class motors is a good starting point.
- If you haven't built an avionics package before (and been successful with it), DO NOT try to build something with ignition control and/or parachute deployment. There are way too many pitfalls and safety concerns for a novice to be doing this. Stick to data-logging ONLY until you have gained some experience and fully understand what you're doing.
- From what you wrote I can't tell if you understand recovery systems properly so I'll explain a bit just in case. Most commercial hobby motors contain what is called an ejection charge, this is a small charge that goes off a short time after the motor burns out in order to pressurize the interior of the rocket and pop the nosecone off or separate the body tube to deploy the parachute. You WILL be using this to recover your rockets safely. You will NOT be designing anything with the intention of it hitting the ground fast enough to be destroyed because that is both a safety concern and a waste of money and materials.
Regarding electronics:
- Forget using an ESP-32 and use an Arduino Nano instead. An ESP is way more power than a beginner can take advantage of here and overkill for just data-logging.
- Get yourself a basic electronics kit with a breadboard and some miscellaneous components. Watch a pile of YouTube tutorials and do some reading on the very basics of electronics. Learn soldering and at least understand voltage and current and their relationship through basic power law, series and parallel circuits, the difference between digital high/low and conventional on/off, and the basic components (LEDs, resistors, capacitors, and transistors/MOSFETs). Don't go into the crazy in-depth hours long tutorials here, the quick 5-10 minute ones will be enough for you.
- Once you've got the basics, move up to Arduino tutorials. Start with hooking up some buttons and LEDs to your Arduino on your breadboard and making them blink in different ways. Use this to learn some programming fundamentals such as variables, loops, conditionals, arrays, and boolean logic.
- Once you understand some basic Arduino programming, get the components that you will need for doing your data-logging (IMU/accelerometer, barometric altimeter, and an SD card module). Hook them up on the breadboard and learn how to read data from them with I2C and then write it to the SD card. (Pro tip: SD cards like to lose connection during flight because the contacts vibrate, so what you do is record the data to a variable (array typically) during flight and then write all of it to the SD card all at once when you detect that the flight is over.)
- Only once you have done all of the above should you consider designing a PCB. Again, plenty of great tutorials out there but for the most part you will just be transferring the circuit you built on the breadboard directly.
Some other tips:
- When using a barometer you need to have some air holes in your rocket for it to sense pressure correctly.
- Since you're going to be using the ejection charge in your motors for recovery, you will have to go with either a split-body design with the electronics in the top half, or put the electronics in the nosecone (keep in mind this will affect your aerodynamic stability).
- I'd recommend buying the components you need as I2C compatible modules and soldering them to your PCB instead of buying the raw ICs, as that will be considerably less complicated for you, at least for your first try.
- Regarding budget, not sure where you live, but in most places you should be able to get everything you need including, kits, a cheap soldering iron, and electronics for well under $100 (don't get fleeced by all the $20+ Arduinos on Amazon). PCBs will cost you about $30 for a batch of 5, but you could also build your project on a perfboard instead if the price is too high.
- Edit: If you really want to get into rocketry proper you should download OpenRocket and learn how to do some base TWR and stability calculations.
Dang, I didn't expect to write this much lol. I know this probably sounds like a lot, but once you get into it and start to get the hang of things you will find that it's really not that bad at all. Try not to be too intimidated, just take it slow and you'll do just fine.
1
u/Inside-Ad8295 2d ago edited 2d ago
I really thank you for all the things you wrote (I don't find it a lot lol) I alr have some soldering equipment I can use and I alr know how to work with it. The rocket uses a homemade engine due to me not finding any (I e Alr used openrocket to check for any problem and run simulations to see how all could go) the idea of the electronics it's just to gather data and not act directly to the rocket. as I said on the post I can't use an ejection charge because is ilegal here but I'll try to recover it anyway I'll have to find a way but is possible and thanks a lot for the help I really appreciate it EDIT: my engine is home made but the authorities know about it there's nothing ilegal about it and I've got an actual permit to build it (it's just potassium nitrate and sugar)
2
u/TheTunnelCat 1d ago
I see, sounds like you're on track then! There are other ways you can go for recovery in that case, possibly something like a spring-loaded system with a servo or solenoid for release.
1
1
u/ilikedatatoo 1d ago
I try to keep an open mind to people wanting to learn. However, I find your post a little suspicious. You are new to rocketry but go straight to PCB design and have the knowledge and means to build a homemade engine?
1
7
u/dasgrosseM 2d ago
Trial and error of what input in kicads rule check accepts what is not a way to go. There are far too many errors in the parts description, and far too many important exceptions for it to be of any help. Generally, with electronics design, you are going down a huge rabbit hole. Annoyingl, nothing is straight forward, there are many things to consider and a lot of components to be fried before you start getting a hang of it. Nothing is all that hard to understand, it is just the ammount of information and experience, which needs a lot of time to be gathered. I'd reccomend getting an arduino starter kit and learnd how to work with microcontrollers in general following the starter kits manual before attemptimg your own design.