PSoC3 Custom Board

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Re: PSoC3 Custom Board

Postby kmmankad » Fri Dec 02, 2011 12:12 am

I was fortunate enough to get a few valuable inputs from the experienced design engineers at Cypress (who made the top-notch high precision analog capable CY8CKIT-030 board http://www.cypress.com/?rID=49524 ) about this board's design.I have taken those into account,and tried to improve it.

Heres the latest batch of changes:
--Added additional vias between the top and bottom layers to improve return paths.
--Crystal routing improved(Capacitors on same side,traces shorter).
--Added reverse polarity protection diode across Unregulated DC Input(VIN).
--Added Fuse to USB supply.
--Added LED for Bootloader Status.
--Widened Power tracks for better stability.
--Differential Routing for SWD and USB tracks.
--Changed back to Type B USB connector,easier to solder.
Attachments
PSoC3_Custom_Board_V2_Rev8.zip
Design Files as of 01-Dec-11,Licensed CC-BY-SA 3.3
(655.2 KiB) Downloaded 526 times
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Re: PSoC3 Custom Board

Postby arakis » Sat Dec 03, 2011 6:20 am

One of your dimension board outlines is not straight, bottom right corner. Also you could move the mounting holes lower and add the one on the left bottom.
best regards FIlip.
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Re: PSoC3 Custom Board

Postby kmmankad » Sat Dec 03, 2011 6:52 am

Yeah,I noticed that soon after uploading :P
About the fourth mouting hole,theres no space.Bad design.. bad >.<
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Re: PSoC3 Custom Board

Postby arakis » Sat Dec 03, 2011 7:01 am

I posted up your board on the blog, I rendered it in shetchup :D
btw the 4th mounting hole could be placed if you moved them lower. as in right in the lower left and right corners.. see the brd file below..
Attachments
PSoC3_Custom_Board_V2_Rev8.brd
(44.22 KiB) Downloaded 281 times
best regards FIlip.
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Re: PSoC3 Custom Board

Postby kmmankad » Tue Dec 13, 2011 7:28 am

Thanks Arakis!... Featured on DP again \m/ ..I've added the 4th hole.

the radio silence is over,and heres more on this project:
-Changed USB routing to comply with guidelines in the USB design spec.
-Decided to remove the external Mhz crystal(but kept pads for a though hole resonator,just for testing)
(A detailed writeup on those changes http://kmmankad.blogspot.com/2011/12/psoc3-custom-board-usb-routing-and.html)
And,sent the boards for fabrication(to a local guy) which I should get within a week of my sending,i.e around the 19th..

There is still a lot that can be changed and made tinier,but the current decisions in parts and their packages are made on the basis of my confidence in their local availability.As I hit the streets for parts soon,I hope to broaden my know of the components available,so I can incorporate them into future changes.
If you have affordable access(read no shipping or heavy import duties) from parts sourced from places like Mouser,Digi-key etc,feel free to use that luxury to better this board's design and layout.
Attachments
EzPSoC3_PCB_Fabrication.zip
Design Files,as sent to the fab house.This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
(654.91 KiB) Downloaded 699 times
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Re: PSoC3 Custom Board

Postby arakis » Fri Dec 16, 2011 3:46 am

are you sure you need those resistors on the USB lines....
best regards FIlip.
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Re: PSoC3 Custom Board

Postby kmmankad » Fri Dec 16, 2011 4:29 am

well,thats what the cypress appnote says...(I wish I didnt though...not able to get 22ohm SMD resistors locally.)
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Re: PSoC3 Custom Board

Postby rohitdesa » Sat Dec 17, 2011 1:16 am

Hey Kartik:

Any reason you're using a USB type-B connector? Why not mini-B? It may be cheaper (it is Rs.5 in Delhi) and since you're using an SMD PSoC, the mini-B will ensure a low overall profile. I may be going shopping in Delhi. Let me know if you need something bought.
Cheers!
Rohit
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Re: PSoC3 Custom Board

Postby kmmankad » Sat Dec 17, 2011 8:43 pm

Well,mainly because I'm not confident soldering it.Also,there was a cross of the D+,D- lines if the mini-B was used.Though I will include that in future revisions.

About the parts,I'm still without the 22ohm,LEDs and 1uF caps,all in 0805.Hope to get them via kitsnspares though.Thanks for the offer,really appreciate it!
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Re: PSoC3 Custom Board

Postby torwag » Tue Dec 20, 2011 2:28 am

Hey,

I just came across your post. I am using the PSoC chips too and I am very interested in a little board. I read a bit through your comments and blog entries.
Here are a few thoughts and apologize if this was discussed lengthy already and I simply overlooked it.

* Why not using a PSoC 5 instead of a PSoC 3? The PSoC 5 comes with an ARM M3 core and gcc as compiler. That means at least from the software side of the PSoC, there is a chance to use only open source software. As for the price, they do not differ so much (Cypress) $18.41 for your PSoC 3 compared to $25.99 for the PSoC5. However, you would get 1 fast SAR ADC, 2 more internal OP-amp and a 32-bit ARM Cortex M3 CPU up to 67 MHz which, compared to the 8051 core, will get you 3 times more MIPS for number crunching. I noticed that many hobbiest people get interested in ARM stuff and hence this board would have double its value. Not only get into programmable analouge stuff, but also as an introduction into ARM architecture. Guess many would overlook the additional $7.5 dollar for these additional features.

* Make sure to select a PSoC which comes with a set of pin-compatible chips. Thus, people might choice to go for one with more RAM,FLASH when prices (hopefully) dropping, or if they want bigger chips for larger projects. This also helps to source for chips if you need to get many boards out.

* One strength of the PSoC is the internal 20bit ADC. However, to make a real use of it, it requires a careful routing in-, and outside of the chip. There is an app-note, which pins should be considered for analogue routing (e.g., avoid pins close to clock lines, etc.)
There is also the need of a good separation between digital and analogue part of the PCB. I would prefer to have one or two dedicated analogue pins on the board (e.g., AD and DA). Maybe using small SSMT connectors, like http://jp.mouser.com/ProductDetail/Hirose-Electric/WFL-R-SMT-110/?qs=x%252biggnnmgNHriCqn0HOi%2fQ%3d%3d. That would allow people to take real advantage of the analogue part of the PSoC.

* P1[0] - P1[2] could be used as normal GPIOs if not needed for programming. You might like to add silk-screens accordingly.

* P12[0]-P12[1] does not have description. Furthermore, P12[0]-P12[3] are SIO pins and differ from GPIO pins which might be worse to indicate in some way.

I know that some of the above ideas might break almost all of your design. Just wanted to point them out.

I do not totally understand the way how you are going to upload new bitstreams to the board. If I understood correct, it would require a miniprog programmer. I am not aware that you can use the PSoC USB port itself. During flashing I think the PSoC itself should be laying there like a dead fish, no way the internal USB could work. Even if this would work, given the nature of the PSoC, people could forget to implement the USB module in there designs and loose the programming ability. Maybe I overlooked some recent progress on the Cypress site here.

I have a couple of PSoC Evaluation Kits and they use an external USB chip for uploading. However, they do not provide any way of accessing the USB from the PSoC side (or they changed this recently in the firmware of the UART-bridge).
This would be really a nifty feature to enable programming over USB (via an external fail safe chip) and use the same USB port as PSoC UART during run-time. It would need to switch between this two modes in some way.
Not sure you was thinking about this already.
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Postby kmmankad » Tue Dec 20, 2011 8:01 pm

First off,Thanks for your interest in my little project! :)
Thanks for all the suggestions.I do plan to implement some form of these(most of them) in the next revision.

I dropped the PSoC 5 idea,since they are available only in TQFP or QFN(as of today).I am planning to make the next revision of this board based on the TQFP PSoC3/5,but thats after this works out okay.

Also,about the programming,I plan to use a USB Bootloader running on the chip.Also,this wont interfere with the USB functionality in the programmed hex.

Also,the intention is to keep the board simple,low cost and easy to use.Since this is my first design(on many fronts),I hope to continually improve this design as I learn more.

Here are some links from my blog that could shed more light on this:
http://kmmankad.blogspot.com/2011/09/psoc3-custom-board-intro.html
http://kmmankad.blogspot.com/2011/09/psoc3-custom-board-design-goals.html
http://kmmankad.blogspot.com/2011/09/psoc3-bootloading.html
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Re: PSoC3 Custom Board

Postby kmmankad » Thu Dec 22, 2011 8:58 am

So the gerbers came in today.I expect the board coming in soon as well,any day now.
I'm currently missing the LEDs,the USB connector,22ohm resistors(why does no one keep these locally?),the 1117 and 1uF caps.I know,I have very little of the BOM.Its partly because I'm anxious to see how this goes,and only then invest more of my tiny hobby budget,and also because I couldnt get these parts locally in the desired 0805.

Here are a few pics,
Top Copper Image
Bottom Copper Image

I used the free online gerber viewer at CircuitPeople.com ,which works great.If you want to see the whole deal(with the excellon drill data superimposed,try the viewer http://www.gerber-viewer.com/default.aspx.)
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Re: PSoC3 Custom Board

Postby rohitdesa » Thu Dec 22, 2011 9:20 am

Kartik:

I use viewplot for gerber analysis. Which board house are you using for the PCBs - Seeed? iTead? iTead has a decent deal on 5units of 5x5. Do you happen to have an old motherboard to scavenge SMDs off? Else, if you're willing to wait for a couple of days, I'm heading to Pune for Christmas. I'll buy you the components you need in the smallest possible quantities and mail them to you.
Cheers!
Rohit
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Re: PSoC3 Custom Board

Postby kmmankad » Thu Dec 22, 2011 7:53 pm

Thanks for the suggestion.I'll use that in the future.
Board house? I wish it were either of those.Its a guy located in Bangalore.I'm getting 5 boards for Rs.1100,with no silkscreen or soldermask.I know,bad deal.But he was the only one who agreed to doing low quantities(and has charged me for it accordingly too,ob).I'll go with ITead or Seeed next time.

Just curious,which one did you use for the boards shown in the reflow soldering post on your blog?
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Re: PSoC3 Custom Board

Postby rohitdesa » Thu Dec 22, 2011 9:53 pm

I used Seeed for that. That was a an order for 100 boards. Got them cheap at about 80cents a board (about INR40) including shipping. But I've tried iTead as well, and both board houses are equally good (just stay within their minimum trace width limitations)
Cheers!
Rohit
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