PSoC3 Custom Board

A catchall for PSoC3 discussions not captured by the other forums.

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Re: PSoC3 Custom Board

Postby radner on Sun Oct 30, 2011 11:38 am

Good idea, SD-Card will be done soon 'cause it's quite simple
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Re: PSoC3 Custom Board

Postby michaeldavid on Sun Oct 30, 2011 7:44 pm

I would suggest 4 mounting holes.

Well done sofar.
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Re: PSoC3 Custom Board

Postby kmmankad on Sun Oct 30, 2011 8:07 pm

Ah yes.I'll add that in the next revision,i.e after the prototype.I also want to add a few additional changes:
-Remove the external pullup to XRES,if programming is fine without it.
-Add an LED or two.
-Mounting Holes
-Get Port 1's unrouted pins out to headers,
-Switch to a Mini USB connector

Maybe even reduce via size and track width to further shrink and shape the board.
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Re: PSoC3 Custom Board

Postby radner on Mon Oct 31, 2011 9:24 am

I can drill mouting holes into the prototype board too, unfortunately these will be connected to GND.

Mini USB would be good because it eliminates a few vias.

I wouldn't shrink the vias at all, 'cause 0.6mm drillers are quite sensitive and I don't know if their are smaller ones available for hobbyists.
May we can get down the traces to about 0,3mm (12mil), I wouldn't go lower 'cause they can easily be underetched and you spend hours and
hours with fault localization, also think when working with traces with 200µm or even less a little dust part could cause a bad trace.

Also the two layers need to fit better, so the "yield rate" decreases rapidly.

Best Regards Phillip
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Re: PSoC3 Custom Board

Postby kmmankad on Mon Oct 31, 2011 10:15 am

Yes,but if youre considering a professional PCB service(as many hobbyists increasingly are) then we can go down to even 6mil tracks and what not.
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Re: PSoC3 Custom Board

Postby radner on Mon Oct 31, 2011 2:05 pm

Yes with professional service thats aint a problem, but if you say it should be a student eval board,
a homemadeable version should stay, 'cause otherwise you could also youse one of the First Touch Starter Kit,
at least as processor board.

For the vias I would even suggest 0.8mm 'cause I broke one 0.6mm driller right with the prototypes.
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Re: PSoC3 Custom Board

Postby kmmankad on Sun Nov 20, 2011 3:33 am

Even though it was good and all,I wasnt satisfied with the initial design.And the power section in my opinion was just rubbish.I ripped up the whole PCB,and started designing from scratch,adding a few things here and there.

Notable inclusions are that of a watch crystal(for the RTC) and a 24Mhz crystal for the chip.I've also taken care this time around to make it breadboard pluginable and done some tighter placement.Final board dimensions are at 2.1"x2.2",from the previously 3x3,so thats good.

I spent a lot of time trying to think of some simple power setups for this board which would be foolproof.Trying to implement my lofty goals,I realized that the routing was getting really messy.So in the end,just went with a simple one, 5V,3.3V select and 3.3V source(USB or DC IN) select.So yeah,you cant run the board off a DC supply at 5V.I could've added a pin or something to allow that,but I don't want unregulated input to the board.(adding another regulator was getting messy)Thats just shabby design.Actually,there is a way to have unregulated input with this board too,just connect the +ve to the central pin on the logic level select jumper,and tie the grounds,ofcourse.

So heres what it looks like
Image

link to the full size image:http://3.bp.blogspot.com/-VRiWKmATfPM/TsjjC2XLGlI/AAAAAAAAAW4/uh861NeOeKA/s1600/02PSoC_CustomBoard_Rev7_PreFab.png
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Re: PSoC3 Custom Board

Postby radner on Sun Nov 20, 2011 11:48 am

Again i have to say that it isn't processable at home, you can't solder a crystal at both sides of the pcb with hobbyists equipment
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Re: PSoC3 Custom Board

Postby kmmankad on Mon Nov 21, 2011 6:49 am

well,I have nothing against a more spread out layout where no vias are beneath the chip,or there is no routing assuming PTH.But the problem is,the Appnotes on PCB Design from Cypress say that the decoupling capacitors should be as close as possible.How do we meet both requirements?
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Re: PSoC3 Custom Board

Postby radner on Mon Nov 21, 2011 2:02 pm

Now we would have to devine what's as near as possible. As long as we use a crystal as main oscillator, this means we won't go beyond, let's say, 30MHz with fundamental wave crystals.

So the requirement for the decoupling is a low impedance path for 30MHz to 300MHz (10x the fundamental for squarewaves should be good), so the parasiteric Inductance should be the biggest problem. So now we could calculate the Inductance for a 0.25 Inch times 0.02 Inch trace on a normal 0.00137 Inch cooper claid pcb (I think this is realistic), which should be about 4nH (with right calculation). This gives us a inductive reactance of about 25ohms for 300MHz.

So if we know look into the datasheets of 100nF capacitors, they add almost the same amount of inductance, even if we use low ESL caps they add at least 10 ohm's.

Know we would have to consider the inductance of the vias, I didn't find any specs for vias. But I think they are quite in the same region than the traces.

Last but not leat we would have to know which trace is more critical, the hot node or the GND side.

But all in all I think that it'll work if we would place half of the caps on the top side (a few 0603 caps are hand solderable) and the via to the bottom GND plane, the other half (if possible for the analogue part and as low esl chip) on the bottom side with a via to the pin. This should work quite well for this design.

By the way, should I send you the board I made and you try to do the vias?

So last point is their a pin compatible PSOC5 on the way? This would be great 'cause I would like to do something with the PSOC5 Chips.


mfg Phillip
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Re: PSoC3 Custom Board

Postby uday1489 on Wed Nov 23, 2011 7:33 am

Sounds great to have those shields. Keep up the good work guys. I hope to see more from you guys. Just a couple of inputs. I am sure people here know about Arduino and what it is made out of. And possibly everybody knows how powerful PSoC3 is. Can we have a PSoC-duino with plenty of shields to play with ?
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Re: PSoC3 Custom Board

Postby kmmankad on Wed Nov 23, 2011 8:01 am

@Uday thats was the intention since the beginning :)
Infact an initial thought I had was to mimic the arduino layout,so those shields can directly be used.But I didnt pursue that further,marking it in my to-do list as something for the future.
Also,I'm curious as to why there are no minimal boards of this kind in cypress' store.Anyway,I have approached the manufacturer with the revised design,and hope that I have boards soon now.

btw,youre the same U2 at the Cypress forums and author at tantra-jnaan,rite?
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Re: PSoC3 Custom Board

Postby kmmankad on Fri Nov 25, 2011 4:30 am

I'm posting the PCB files here hoping someone fabricates them via any service(since the boards are 2"x2",it will be cheap via most services like Seeed,Itead etc) I will come back to active development after my semester end exams.
Attachments
PSoC_Custom_Board_Prefab_V2.zip
EzPSoC3 - PSoC3 board for hobbyists and students.
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
(643.26 KiB) Downloaded 55 times
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Re: PSoC3 Custom Board

Postby radner on Sun Nov 27, 2011 1:00 pm

Hey

I edited the board as far that theyre are no vias under the chip, so the board is easier to manufacture.
For sure the tracks got a bit longer due to the small pitch of the ssop package.
I don't think that this will decrease the device performance at all.
I think the bigger problem will be the high frequency nodes, like the crystal or the USB.

By the way: where did you get the packages from? the resistors and caps are quite unusual? Whats wrong with the standard things out of the rcl library?

Best Regards
Phillip
Attachments
PSOC3.rar
(515.51 KiB) Downloaded 46 times
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Re: PSoC3 Custom Board

Postby kmmankad on Mon Nov 28, 2011 12:21 am

Hey,
good work on the re-routing.I guess you can now give the fabrication a shot.

This time around,I referred to these docs during routing:
http://www.cypress.com/?rID=43337 AN61290 - PSoC® 3 / PSoC 5 Hardware Design Considerations
http://www.cypress.com/?rID=37884 AN54439 - PSoC® 3 and PSoC 5 External Oscillator [I didnt implement stuff mentioned here that meticulously,perhaps you can assist there]

All parts(except for the chip itself) are from the Sparkfun Eagle library,since those are proven footprints,and for many parts,this better than the default eagle libraries.I chose the sparkfun lbr,since this is my first fabrication,and I didn't want any stupid errors of components not fitting the footprint etc.
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Re: PSoC3 Custom Board

Postby radner on Mon Nov 28, 2011 3:23 am

I found a little error in the shematic. The caps at the voltage regulator will ruin the regulator.

'Cause if the Cap on the right side is bigger than that one of the left side, current will flow trough the regultaor in the reverse side at power off.

So you could simply change them, add a diode at over the regulator. But I don't think this is necessary, i simply replaced the 100µ with a 100nF.
So I could make some further improvements with the crystal routing. I'm going to show the result to you tomorrow.
If their are problems with that we could use a 4.7µF ceramic cap 'cause they are smaller than elektrolyt ones.

Best regards

Phillip
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Re: PSoC3 Custom Board

Postby kmmankad on Tue Nov 29, 2011 2:18 am

Thanks for spotting that.Fixed it,and I'll add a few more cosmetic changes I had in mind,and will upload soon.
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Re: PSoC3 Custom Board

Postby radner on Wed Nov 30, 2011 12:37 am

So here are my edits from yesterday.

I think I'm going to fabricate a prototypre of this version, to check it for errors.

Best Regards

Phillip
Attachments
PSOC3_Custom_Board.zip
(873.79 KiB) Downloaded 58 times
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Re: PSoC3 Custom Board

Postby radner on Wed Nov 30, 2011 12:49 am

I'll order some hardware for the project soon, what PSOC3 device should I use for the first Prototype?
Their are quite a few available in 48pin ssop package
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Re: PSoC3 Custom Board

Postby kmmankad on Wed Nov 30, 2011 1:34 am

its the CY8C3866PVI-021 you should go for.Its the most feature rich SSOP part,and most importantly,it has USBFS.
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