topic Re: LPC812 Breakout board & Eagle Library in LPC Microcontrollers

LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:50 GMT

Content originally posted in LPCWare by cpldcpu on Tue Sep 17 13:04:12 MST 2013
Since the parts are finally available for order, I designed a small breakout board for the LPC812M101JPH20. It is not tested yet. You can find the design files here:

https://github.com/cpldcpu/LPC812breakout

As a bonus, I created an eagle library for all LPC800 parts:

https://github.com/cpldcpu/LPC812breakout/tree/master/Eagle%20Library

Any ideas or feedback?

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:51 GMT

Content originally posted in LPCWare by cpldcpu on Tue Sep 17 13:05:44 MST 2013
?

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:52 GMT

Content originally posted in LPCWare by Pacman on Sun Sep 22 14:02:13 MST 2013
Well.. I think it looks quite pretty and I like the size, but I do have some comments/suggestions.
I've only looked at the PNG pictures (I don't use Eagle).

[list=1]
[*] If this is made for hand-soldering, it's a very good idea to have the traces connect to the side of the pad which is far away from the component. If not doing this, you'll experience that pads just fall off as soon as you give the PCB too much heat or you do rework using a soldering iron.
[*] I don't like 90° turns. try eliminating as many of those as you can, so you get 45° turns.
[*] Adding a ground-plane doesn't cost extra, and it's more environment friendly (less etching acid needed, less copper down the drain). I know it's only a very, very small adapter, but it might reduce RF noise a little.
[*] Try making your traces head for the center of the pins/pads. (look at the 3V3 via in the middle/center and the GND pin in the top/center)
[*] I believe you could increase the trace width slightly; this might lower the PCB cost.
[*] Avoid 'pockets', especially when traces are thin. Pockets make it easier for acid to 'hide' under the soldermask and slowly ruining the PCB. (No, it's not very likely to happen ws the PCBs are usually washed quite well, but it's good layout practice).
[*] It's possible it'll be very, very difficult to read the silk screen. I tried zooming it to 'actual size' and as I believe that most manufacturers will have a 10 mil silk screen, you might just get a lot of white dots. 'ISP, Reset' and 'CLK' will most likely be readable, though. C1, C3, R1, R2 could easily have larger font size. Try keeping font-size 35 mil (0.9mm) or larger.
[*] Where did C2 go ? :)
[*] Try keeping traces as far from eachother as possible. (for instance, the two top/left traces on the bottom side does not need to get so close to eachother and GND gets very close to Rst. P00 gets very close to the corner of P14). I haven't checked all, so best bet is that you should try checking one pin at a time, going through all pins and traces. It may help to think of the signals as enemies that don't like eachother - keep them as far apart as you can. ;)
[*] Always start with a prototype run of low quantities.
[*] If your PCB is NSMD, pads tend to be torn off quite easily by a soldering iron. If it's SMD (Solder Mask Defined), the solder mask that overlaps the pad makes the pad stronger, thus it's more likely to stay on the PCB. I recommend SMD for hobbyists and breadboard adapters. NSMD should usually be used if you're working with BGA, but it's not always the case. Sometimes you might have to mix the two.
[/list]
Most important: Thicker traces, connect traces on the side of the pads facing away from the component.
Those are all just suggestions; I think the PCB would work as it is. :)

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:53 GMT

Content originally posted in LPCWare by Raiden on Fri Sep 27 00:01:54 MST 2013
Did he ever revise it? What values did he use for the breakout? This looks pretty cool. :)

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:53 GMT

Content originally posted in LPCWare by rocketdawg on Fri Sep 27 09:53:17 MST 2013
They moved the ISP pin in Rev 4C parts. I didn't look at the files to check if this was the case.

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:54 GMT

Content originally posted in LPCWare by cpldcpu on Fri Sep 27 10:48:29 MST 2013
Hi Pacman,

thank you for all the input. I had already sent the design to OSH-Park for a first test, but will make a second iteration to take alle your comments into account.

I used the Eagle-Autorouter for the routing. This is the reason for many of the issues you mentioned.

1. I Have never experienced that, however I usually order boards with silk-screen.

2. -> eagle wonkyness, i could possibly fix it manually

3. That would mostly be a floating plane, or i'd have to add more vias.

4. -> no idea how to make eagle not do this

5. Good point, I should do that.

6. Pockets? Not sure what you mean by that.

7. I agree. I should probably make is larger and only number the pins. I'll see how it looks on the prototype

8. That was part of a 3v3 voltage stabilisator circuit. good point :)

9. Well, it passes OSH Parks DRC so i guess it is ok.

10. Done

11. What is NSMD? Not sure what OSH Park is using.

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:54 GMT

Content originally posted in LPCWare by cpldcpu on Fri Sep 27 10:49:01 MST 2013

Quote: Raiden
Did he ever revise it? What values did he use for the breakout? This looks pretty cool. :)

Thanks! No revision yet. I'll let you know how the prototype turns out.

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:55 GMT

Content originally posted in LPCWare by cpldcpu on Fri Sep 27 10:49:25 MST 2013

Quote: rocketdawg
They moved the ISP pin in Rev 4C parts. I didn't look at the files to check if this was the case.

It's on P0_12. By coincidence I downloaded the new UM revision :)

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:56 GMT

Content originally posted in LPCWare by cpldcpu on Sun Sep 29 02:51:46 MST 2013
[see new version below]

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:56 GMT

Content originally posted in LPCWare by cpldcpu on Sun Sep 29 06:09:34 MST 2013
I designed a new revision of the board, taking all your suggestions into account:

Changes:

- 10 mil traces, no 90° bends, ground plane where possible.
- Font size for pin labelling increased.
- Removed SWD port to reduce complexity and size. If needed, the port can be accessed at the broken out pins.
- Included 3.3V regulator, since the driving ability of those includede in the USB to serial converters is limited.
- Removed debouncing cap from reset switch.

Any other ideas? I am still pondering one question: LED or no LED?

Fun fact: The entire board is smaller than a DIP LPC1114.

Edit: Replaced images with v2.2, which also has 5V broken out.

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:57 GMT

Content originally posted in LPCWare by Raiden on Mon Sep 30 00:25:42 MST 2013
#6: Pockets deals with 90 degree shapes, in segment 1 of the picture you see a 90 degree shaping on a T intersection, in picture 2, he uses eagle cad to add in routing to prevent the 90 degree angles into 45 degree angles, in picture 3 you see the better version.
[img=484x1101]http://i1334.photobucket.com/albums/w648/mrcookie2000/nerdz/eagle_cad_beveling_zpsbadd5d41.gif~original[/img]
A submerged PCB in acid is rinsed off, and the surface tension of the acid can potentially "cling" to sharp angles on a PCB edge, creating a pocket. Softer angles are less likely to have this problem.

#11: This explains SMD vs. NSMD.
[img=596x304]http://i1334.photobucket.com/albums/w648/mrcookie2000/nerdz/5283Fig011_zps33395011.gif~original[/img]
SMD-style silk screens are supposed to reduce bridging when dealing with fine pitched BGAs. IPC-7095B suggests the SMD style silk screens as well because it's less likely to lift off when excessive heat is applied.

I dont claim to be a expert, so I could be wrong. Another thing I looked at, is what is considered the right "orientation" on your board? I dont know if it matters, but where I work we usually have a "compass" on the bottom left. Or even a arrow. Maybe not usefull, as we do R&D, and I'm more a SMT Tech then a PCB Layout Engineer. :P

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:58 GMT

Content originally posted in LPCWare by cpldcpu on Mon Sep 30 01:01:41 MST 2013
Hi Raiden,

thank you very much for your explanations. That seems to make a lot of sense. I noted I still had two right angle left in the board, but there is no T-intersection. Since I increased the line width above the minimum spec, I hope there will not be any issues with pockets.

SMD vs. NSMD seems to be a layout issue rather then PCB manufacturing issue. It seems that all the libraries I used are of the NSMD style. The LPC800 library is based on Microbuilder's footprint lib and the rest is from the Sparkfun eagle libraries. I don't know whether NSMD will cause any issues, but it seems to be a common style. Things may be different with BGA though.

Again, thanks to everybody for the feedback. I learned a lot. I will have the prototype of the first version in about two weeks and that of v2.2 in four weeks. I'll let you know how it turns out.

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:58 GMT

Content originally posted in LPCWare by Raiden on Mon Sep 30 06:50:24 MST 2013
I was going to ask, is this compatible with a breadboard? Might be something worthwhile to do.. :)

I guess it depends on the actual use of this thing? I know on Arduino boards they have a "on" led, a single "it works" led, a bunch of circuitry for really slow usb > serial > programming interface, and a voltage regulator for pulling power from the USB connection.

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:08:59 GMT

Content originally posted in LPCWare by cpldcpu on Mon Sep 30 09:33:12 MST 2013

Quote: Raiden
I was going to ask, is this compatible with a breadboard? Might be something worthwhile to do.. :)

I guess it depends on the actual use of this thing? I know on Arduino boards they have a "on" led, a single "it works" led, a bunch of circuitry for really slow usb > serial > programming interface, and a voltage regulator for pulling power from the USB connection.

It is compatible with a bread board, this is exactly what I designed it for. The connectors are 6 pins apart, leaving ample space on the breadboard. The board can be powered and programmd by a cheap USB to serial converter. The funtionality is basically the same as that of the LPC810 mini kit. Just with a LPC812 and BB compatible...

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:09:00 GMT

Content originally posted in LPCWare by cpldcpu on Fri Oct 11 00:04:55 MST 2013
I received the first revision PCBs and built a first prototype. Image attached. As you can see it fits nicely even to a small breadboard.

I should receive the boards for the redesign next week.

Edit: Added size comparison to LPC1114

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:09:00 GMT

Content originally posted in LPCWare by Raiden on Thu Oct 17 20:59:36 MST 2013
You should try cleaning the rosin off, to prevent changes to the solder/solder mask. It looks cool, what's the breakout pins distance? 0.1 inches?

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:09:01 GMT

Content originally posted in LPCWare by cpldcpu on Tue Nov 19 09:22:55 MST 2013
In the maintime I received and built the revised board. It came out pretty good and works nicely, thank you again for all your input.

All relevant design files are on github:

https://github.com/cpldcpu/LPC812breakout

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:09:01 GMT

Content originally posted in LPCWare by cpldcpu on Tue Nov 19 09:25:13 MST 2013

Quote: Raiden
You should try cleaning the rosin off, to prevent changes to the solder/solder mask. It looks cool, what's the breakout pins distance? 0.1 inches?

It's actually not rosin, but lint from the cloth I used to clean it. Should get some proper wipes.

The pin distance is 0.1 inches so it fits on a breadboard. See pic.

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:09:02 GMT

Content originally posted in LPCWare by rkallal on Wed Jan 29 20:52:14 MST 2014
Is there a parts list for the board? I don't use eagle and just want a list and sizes. I picked up 3 boards from oshpark and now want to build them up.

Re: LPC812 Breakout board & Eagle Library

lpcware — Wed, 15 Jun 2016 20:09:02 GMT

Content originally posted in LPCWare by cpldcpu on Wed Jan 29 23:35:27 MST 2014
I added the bill of materials to the repository. I hope that helps. You may also get away with 0603 if you do not have 0805.