General purpose board designs for P2 Edge modules
Rayman
Posts: 14,744
Think this board design is finished...
Will hopefully provide a general purpose board for use in several projects.
Update: Everything seems to work, so here's the Eagle files for the board.
Note: Next revision will have some extra caps all over, just in case needed in future.
Update2: Here's another version "Robot 1f" that I plan to upgrade my robots with.
Comments
Can you render a 3D model?
Nice Ray. I think your I2c follows the qwiic/stemma qt standard, right?
I like how you have the single neopixel but provision for offboard too
I can, but it's not that great...
Maybe I should try to import this eagle file into KiCad... Been meaning to try KiCad for a while now...
Thanks! Wasn't meaning to follow any I2C standard, but would be happy if it is
Neopixels are fun... Had to put one in... The three pin header could be used for something else, if not using the neopixel...
Just occurred to me that I should rearrange the pins into the servo order...
Qwiic standard
https://www.sparkfun.com/qwiic
from that page,
All Qwiic cables have the following color scheme and arrangement:
Black = GND
Red = 3.3V
Blue = SDA
Yellow = SCL
Sparkfun/Adafruit/Grove use the same, either with 2mm or 1mm pitch. The colors match RJ11 4 core phone cable ordering
Ok, I added in a Qwiic connector. That was a good idea.
Easy to do for me as Sparkfun uses Eagle too and posts their schematics...
Looking good Ray.
Was able to open with KiCad and generate 3D view...
Didn't populate any of the parts though... Guess there's no way it could.
You would have to switch to parts from KiCAD or go into the footprint editor and assign 3d models to the footprints. You can find models for just about everything out there!
Think I should have added a reset button...
Maybe I can solder one onto the Edge board instead...
@Rayman In KiCAD's PCBnew tool, double check on each footprint outline [or single check, press E]; in the "Footprint Properties" window, select the '3D Settings' tab. This is where you add the 3D .stl files and .wrl files. Then render...
Boards are here. Guess I can say next week if they work or not...
In the meantime, this modified version is for a robot in development.
Board seems to work. I forgot to order the 12-pin SMT headers and the double-USB connectors..., But, USB works with a single-USB connector and there's not too much that could go wrong with the 12-pin headers.
Also, didn't have a sound chip handy when populating the board, but added it in later with hot air gun and audio works. VGA, RTC and RGB LED work too. Almost fully tested now.
Wasn't totally sure the reflow oven would work with this P2 Edge SMT connector, but seems to have worked out perfectly.
Saves a lot of soldering...
Nice board Ray.
If you do a rev, the SD should have a bulk and bypass cap as close as you can to the socket. Looks like you only have 1 cap.
I’ve not looked at the 12 pin hdrs. Is it possible to have both smt and thole footprints?
BTW I don’t see bulk caps on you 12 pin headers.
@Cluso99 Thanks for the feedback. It's true I just have one 1 uF cap next to uSD card. I see the Parallax adapter for P2 has two 4.7 uF caps. I could add an extra cap there.
Putting thru-holes on top of 12 pin headers is an interesting idea. Maybe I should do that.
I tried putting a couple thru-hole headers on these pads when put in oven. But, that was a bad idea as they melted into a pile...
Now that I look closely, I see the P2 Eval board does have caps at the 12 pin headers. Maybe I should do that, probably have room.
Guess I'm thinking that whatever is getting connected there will have it's own caps.
Still, there is plenty of room there. Perhaps I will add caps there.
Hi Rayman
You'll never regret from leaving some land patterns, for the pads of any eventual smd ceramic caps you'll find useful to assemble at these "kite-flying lines" VIOs.
If possible, preview for pads that enable mounting a low capacitance one (10 - 100 nF), closer to the 80-pin card socket pads, while leaving another set, at the same net, for a 1 uF one, closer to the pin headers they feed power to.
In a future time, looking at them (eventually still free), perhaps the main question will not be "why?", but "why not?".
Ray,
If you do a redesign, you might consider swapping the SD with the audio as you really want to keep the SD lines short. Would be much better if the SD were on the P2-edge. Long lines are going to limit the max clock.
@Cluso99 Have to draw the line there, but I'll keep that in mind for the future...
Tested out some more stuff and everything seems to work. Posted Eagle files to top post.
Next version will have extra caps as suggested. Maybe I'll add some big electrolytics too...
No Ray, big electrolytics are the wrong way. It’s a very old method used in power supplies in years gone by, and no relevant for today’s designs, and often detrimental.
I just saw some electrolytics on a P2 edge breadboard from Parallax.
I think that’s the best way to get 100uF and up...
Design very much depends of the actual power source. Many designs these days use 5V USB supplies, and here high value electronics capacitors are detrimental to the design, and often violate the supply specifications.
Was reading the parallax breadboard has servo headers. That may be why they have the big caps.
Don’t envision needing that here, but doesn’t hurt to add some holes.
Correct. They are super low ESR polymer caps to provide a bit of board-wide support and to support servo surges.
Just wondering if I may solicit some advice on the topic.
As far as the bulk capacitor and the bypass, it seems that additional filter circuitry would be needed or maybe a band stop filter.
Two caps in parallel creates a bigger capacitance the sum of the two. As appealing as it sounds, I just wonder if it really works. Can’t really verify the source, and not sure if my reference has anything specific on this trick (Texas Inst. PCB design guidelines).
Great topic I wish more people would contribute with their boards. Nice board too!
Not too many places offer nice 3D models. Just a black box. Why?
The board uses SMD type connector for Pr while Mouser has THT connectors in stock - where do you buy these SMD parts?
With its fragmented sentences, Nick..., another bot there me thinks.
Posted files in top post for a variant that's the right size to upgrade some robots with.
Been testing it out... Everything seems to be working...
Has a connector for the Arducam OV2640 that I'll test next...
Finally got around to testing out the DVP camera interface. It works!
Propeller Code Generator can make code that works with this, but pin selection for control signals has to then be modified by hand.
Excellent work, Ray (as always)!