LibrePilot Forum
Development => Hardware => Topic started by: nitromethane on April 20, 2016, 12:25:10 am
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So I had this idea rattling around my head of a RevoNano compatible FC in a DIP-like package that can be soldered or socket mounted to something like a PCB frame or something for a while now.
Last weak I started playing around in KiCad and started to work on a PCB and now finaly have something to show.
I'm kind of interested what you guys make of this :)
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I kind of like the idea. I've had ideas in the past of designing something similar, but making it stack-able.
Have you seen the Microduino boards? https://www.microduino.cc/ (https://www.microduino.cc/)
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Yes, stacking was also an idea with this. I could eventually try to make an OSD, OPlink, Brushed ESC for micro quads, base board with power distribution and voltage/current sensor etc. modules compatible with this footprint...
As for the current board design, I think I'm pretty close to being done.
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Yes, stacking was also an idea with this. I could eventually try to make an OSD, OPlink, Brushed ESC for micro quads, base board with power distribution and voltage/current sensor etc. modules compatible with this footprint...
As for the current board design, I think I'm pretty close to being done.
Hi nitromethane, this is one of best hardware ideas I have seen recently. It would open up a lot of possibilities for hacking and experimenting with this flight controller.
Since Kicad is open-source, will you make your files also open ? I can imagine lots of hackers would pick it up, start prototyping on breadboard customizing design and coming up with new interesting applications. Also the list of supported hardware would potentially grow with this. It looks really great :) Maybe someone would pick it up and made it pin-compatible with RPi Zero :)
DIP package would be really great for improving this platform.
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I really like this idea as well. An obvious thing would be to design a 'motherboard' with connectors that can easily be used.
/F
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From what I can tell on the microduino, they have larger diameter holes for the headers so that the machined headers can sit flush with the board. It makes for a very compact solution.
I would be interested in seeing the pinout for the headers to see what would be available for communicating between boards. Have you considered adding a CAN transceiver? I really like the idea of using CAN for inter-board communications, and you can get pretty small transceivers that work at 3.3V.
You might also look at the Craziflie 2.0 expansion port for ideas: https://www.bitcraze.io/2014/08/crazyflie-2-0-expansion-port/
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Agree with m_thread: The user will nedd a "motherboard" to which the Flight Controller connects. Please, please design that motherboard with 30.5 spaced appart holes on it!!. They don´t even need to be 4. Just 2 will suffice but without them mounting will be difficult.
Regarding connectors. You will need some that are either tight enough to prevent the FC from moving, or flexible enough to dampen the airframe vibrations.
Really like this idea and would love to see it came into fruition.
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Unfortunately, I think it's going to be difficult to make something with larger components with this design. For example, the RFM22B module used on the OPLink/Revo is 16mmx16mm. I don't know the exact dimensions of this board, but it looks like the space between the headers is 15mm or less. Even if you put this on a CC3D/Revo sized baseboard, I don't think you're going to have room for the RFM22B unless you use a surface mount connector.
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Just for fun and to address my needs for my small fpv copters I designed this thing. with 5V regulators, filter and surge protection(to prevent damages due to escs with regenerative braking):
it would be cool to go further with this design toward a "pdb" and flight control board that interconnects using hirose board to board connectors :)
(yes i hate wires :) )
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First of all I'm glad you guys like the idea :)
About the open source thing, yes I intend to go open source.
This will be my first open source project so I could use some advice. I'm thinking of putting it on github under something like a CC-BY-SA licence
CAN bus would be nice, but as far as I can tell (maybe I missed something) the STM32F411 doesn't have it.
The board as it stands is 17x32mm, can be a bit less if I trim it down a little bit, pins are on a 12x6 100mil spaced grid. Maybe I could add a little bit of squeeze by removing redundant power pins (there are ground and power pins on each corner), but that would be on the next version.
Adding RFM22B to the motherboard could prove to be a bit of a pain in the ass with this package, but I can still try.
For now, I'll start working on a basic CC3D style motherboard, then maybe a PDB...
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That's too bad about CAN, but it looks like you're right.
Speaking of hirose connectors, I designed this board a while back but never even soldered one up to test:
(https://644db4de3505c40a0444-327723bce298e3ff5813fb42baeefbaa.ssl.cf1.rackcdn.com/uploads/project/top_image/aJ6c2oxP/i.png)
(https://644db4de3505c40a0444-327723bce298e3ff5813fb42baeefbaa.ssl.cf1.rackcdn.com/uploads/project/bottom_image/aJ6c2oxP/thumb_i.png)
It includes an STM32F411, the standard sensors, a dual voltage regulator, LEDs, and a hirose connector that breaks out pretty much all the remaining I/O. It's 15mm on a side.
Part of the reason that I didn't pursue it further is that the I/O is so dense it's hard to route it all out on a 4-layer board.
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OK, I quickly did a basic breakout board for my DIP Nano. It's as basic as basic can get.
This should be a good starting point to add things to...
I should probably think about surface mounting the DIP Nano...
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I'm thinking of designing a carrier board with integrated BL ESCs and Current/Voltage sensing capability, which could be a useful thing for a micro quad.
Any ideas where should I refer for some ESC designs??
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Most of designs are commercial, but maybe this http://vedder.se/2015/01/vesc-open-source-esc/
If he would make this ESC smaller that would be a thing :)
Commercial designs are more up to date though (like Littebees or KISS24), one can make pads for soldering those ESCs.
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I'm thinking of designing a carrier board with integrated BL ESCs and Current/Voltage sensing capability, which could be a useful thing for a micro quad.
Any ideas where should I refer for some ESC designs??
Actually there are a lot of cheap, high quality and small devices available nowadays (littlebees, xm20a to name a few) .
it's hard to beat their size/price/quality, so the best bet is to have a carrier board that may hosts them directly.
This also allow you to quickly change a single esc without a lot of issues in case of failures.
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Amazing idea with the carrier board, was thinking among the same lines just with castellated holes, ofc minus the mad skills you guyz got to actually carry out the idea.
Loving the work you guyz have done so far, eager to see how this evolves! Just reading and watching your work makes me feel you guyz are onto something big!
Been busy lately, a lot, but thought to just share a glimpse of thoughts i had for some time now.
I thought in lines how it perhaps might be an fc hardware design standard as well, simply by having and IMU board with MCU AND IMU IC's while the only difference between the projects/fc boards would be the 'motherboard', that is, the circuitry approach/design.
If standard accepted, the first manufacturer to offer such IMU board would be able to offer it for best price of all IC's since everyone would now be a part of group buy in range of 1000 + units instead each individually aprox 200 units per batch.
Anyway, don't mind me the layman, keep up the amazing work!
If it comes to being LP hardware, when time comes please let me know, I would like to contribute with at least some funds since I can't with required skills.
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Check out the PDb from Epiquad:
https://www.youtube.com/watch?v=sudKab_9TNk
https://quadcoptersenzo.nl/en/epiquad_epipdb
Sort of what Alessio has in mind. Minus the Hirose connectors.
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Mateusz and a_morale make a valid point about just using ESCs that are already on the market.
It would make sense to just design a PDB carrier board with current/voltage sensors, 5V step-down regulator and some solder points at convenient locations.
Something similar to what lucas pointed out.
I'm also coming to realize, that while I tried to create a nice and small board (which was a bit of a pain designing a two layer PCB), it's footprint is turning out to be a bit of a pain to combine with other things.
Still, I like it and want to make a prototype, so if needed, surface mount headers it is then. (example: http://si.farnell.com/samtec/ssm-112-l-sv/receptacle-2-54mm-vert-12way/dp/1668266 (http://si.farnell.com/samtec/ssm-112-l-sv/receptacle-2-54mm-vert-12way/dp/1668266))
I'll see if I can add a little bit of polish to the board design and then probably order some PCBs...
Also that open source VESC thing that Mateusz pointed out looks really neat and I have components on order to build a couple...
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They are pricier but you cant go wrong with SMD Machine Pin Headers:
http://www.proto-advantage.com/store/images/PRODUCTS/MPH100IMP40F-G-V-SM_0.JPG?osCsid=jr8cv0vlnc3sg7h5ck436ieie3
http://www.proto-advantage.com/store/product_info.php?products_id=1900031
My suggestion:
Go for Stackable 36mm x 36mm boards.
Picture this: a VTx + OSD stacked on top of a Radio Rx, stacked on top of a Flight Controller, Stacked on top of a PDB....
My mouth is watering... ;D.... Where do I send you money?
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I might try to do a full Revo or Sparky2 in a 36x60mm stackable format some day...
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Here's something I'm working on, similar in terms of esc carrier board. Nothing special, merely food for thought.
There's few more photos here, https://forum.librepilot.org/index.php?topic=1436.0
(https://forum.librepilot.org/index.php?action=dlattach;topic=1436.0;attach=2723;image)
(https://forum.librepilot.org/index.php?action=dlattach;topic=1436.0;attach=2729;image)
(https://forum.librepilot.org/index.php?action=dlattach;topic=1436.0;attach=2731;image)
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So, I was thinking, having done the work to make the small dip footprint Nano, it shouldn't take too much effort to stretch it a bit and have it on a 36x36 board.
That would probably give me enough board space to weld on a RFM22B module.
Now, looking at the Revo schematic, there are 5 signals between MCU and RF module, 4 being standard SPI lines and one Interrupt line.
Looking at how Nano is wired up, on Rx input port there are SPI signals on pins In6 (SCK), In5 (MISO) and In4 (MOSI).NSS could be wired to In1 and interrupt could be wired to In3, leaving In2 usable for PPM.
Would that work??
Also I'm a pretty poor programmer and we'd need a proper programmer to get the software sorted (maybe I could try to do it, but I'd probably make a mess of things...)
I'm guessing that due to the modular nature of firmware and the fact that device drivers and OPLink code are already written, that shouldn't be too hard (??)
Any toughts?
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Nano on 36x36 with RFM22B added sounds like a Sparky 2.0 :)
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I've been messing around in KiCad some more and came up with something that should be a 6 channel brushed ESC + Voltage/Current sensor + Buck-Boost converter enabling 1S and 2S LiPO operation and should be stackable with my NanoDIP design.
Mosfets should be good for up to 5A each which is more than plenty, the main current limitation is set by PCB traces, which I'm thinking of laying some solder on top to increase their current carrying capability.
There's also some space left on that tiny board which I could probably use for a simple low voltage warning...
I'm not certain that I'm quite happy with the design just yet, but am really interested what you guys think of it.
Other than that, I'll probably be ordering some PCBs in not too distant future and will try to build a prototype and then make the designs public...
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I love it :) I wonder if it would be possible to fit small lost model alarm (buzzer).