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Testing the PCB...

A project log for Model rocket with active stabilization

By means of motor vectoring

Oriol CasamorOriol Casamor 01/09/2019 at 22:566 Comments

The board is working, voltages regulators work, led is ok, .. but unfortunately the footprint of the SPI Flash was incorrect ... I have to decide if I re-do the PCB or make some kind of workaround :(

Discussions

Xasin wrote 01/11/2019 at 07:30 point

Hm, there are a lot of DIP components here? Was that for ease of soldering, or because they are less suceptible to damage by the rocket's vibrations?

In any case, this does look like a very nice PCB, so I'd recommend just wiring up the flash with some enamel copper wire ;)
What do you need it for though? Flight data recording?

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Oriol Casamor wrote 01/11/2019 at 16:57 point

Hi @Xasin ! My reasons are mundane. In previous projects where PCB dimensions were an important issue I used SMD components. In this project, the body tube is D15cm, so there is no need to miniaturise. Specially, since I am not an electronics professional, the chances of errors in design are important, and I prefer to be able to re-use or replace damaged components. I also spend less time soldering.

I want to record all relevant data in order to be able to diagnose the performance of the system after the flight. This includes time stamp, height, 3 accelerations, 3 rotation speeds, , servo set points, servos real positions, and state variables of the control algorithm and the software in general.

Also, what do you recommend me, enamel copper wire or regular wrapping wire?

Thanks for your interest,

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Xasin wrote 01/11/2019 at 18:40 point

No problem, this definitely is an interesting project for sure! If you have a few IO pins free, I think you should use an SD card for this though.
From what I know they can be accessed via SPI from an AVR, and there's probably a library or two around to write text into a FAT32 text file. It'd be plenty of storage space AND easy to read out later ^^

And I do understand your soldering requirements, yeah ^^'
Just use whatever wire you have around, provided it has an easy to remove copper insulation, With some enamel wires you can just melt the coating off by holding it against your soldering iron for a bit, which makes things quite easy to use!

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Oriol Casamor wrote 01/11/2019 at 19:33 point

I do not like using SD cards because it relies in the phyisical contact of the connectors. Because of the acceleration, it is possible to have a write problem and lose all your data.

Also, I had problems before with SD cards because there is very poor control of the data flow (at least with the lib I used). Even if I called flush(), the libraries writes for a long time at a very spaced times that I do not control. With flash memory I feel I have the power to control the data flow times.

The only mechanical part I use is the switch, and the button. Other hobbyists have had problems with more bulky switch, so I stick to the smallest and most stables I can find.

Thanks for your interest! I will keep you updated :)

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Jarrett wrote 01/09/2019 at 23:25 point

Workaround for sure! Very do-able with this PCB, I believe in you! :D

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Oriol Casamor wrote 01/10/2019 at 07:49 point

The people have spoken! I will give it a try.

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