LPC176X Libraries

[bobi-one]

I was searching for LPC1769 schematic or footprint library for Orcad or Eagle but I did not find in the site. If some one have all ready designed one, I'll be greatfull if you can share it.

[Zero]

Wrong site

Look at CADSOFT

http://cadsoft.de/cgi-bin/download.p...iles/libraries

and you will find: LPC1xxx-v6.lbr

[Rob65]

Wrong symbol

Who ever invented that you should create one big symbol with a zillion pins should be quartered.
It might be OK for chips like the lpc1114 or lpc1343 but as soon as you get to the larger variants with 56 or more I/O pins this is absolutely unreadable.

I would suggest to split the symbol into different symbols for the different IO ports, power/clocking and maybe even USB/Ethernet as separate symbols.
And add the special function names only for those you use with the GPIO port numbers on the outside - the LPC1xxx-v6.lbr has the GPIO names on he inside on the right hand side of the symbol making it much harder to read - and thus you will make mistakes when connecting nets ...

BTW, it is a good idea to scrap all the common libraries from Eagle and create your own versions. I took the resistors.lbr and got rid of all the parts and footprints that I will never use and I gave some more common names to some of the names that cadsoft came up with.

Regards,

Rob

[bobi-one]

Indeed the simbol is kind of a hard to read. And plus i dont know how to work with eagle, its kind of stiff. I will try to do custom symbol in orcad from the lpcxpresso schematic, there the chip is nicely separated.

[Rob65]

Originally Posted by bobi-one

And plus i dont know how to work with eagle, its kind of stiff.

Eagle comes with a nice tutorial with a section on how to create your own library components. Spend one hour on the tutorial and you will be able to create (almost) any library component you want.
Once you understand the concept of the library it's easy: A device contains one or more symbols (possibly the same symbols when you have something like a quad nand) and one or more footprints. Then you connect the signals from each symbol to a pin on the footprint. If a device has multiple footprints it means there are multiple variants (i.e. different packages).
The only thing is that it is not possible to no connect signals to a pin. So for the HVN33 and LQFP package variants of the lpc chips where some signals are not available on a pin you need to create a new device/symbol pair.

If you have a free choice between Orcad and Eagle then do check what formats your PCB vendor understands. I work with a number of PCB makers who also accept Eagle designs (so they can fix my PCB errors if I am in a hurry) next to Gerber files. And they also provide their design rules in an Eagle format, making it easier for me to check the design for PCB production problems.

Rob

[NXP_Europe]

Hello Rob,

if you have a better solution for the Eagle files (layout, names, port choices etc.), with a many pins, please send us an example.

Thanks in advance.

[Rob65]

Attached is my version of the lpc1754
I have split the part in 5 different symbols, one for each port and one for power and clocking. The symbols for port 2 and 4 are smaller than port and 1 - I had been thinking of combining those but I left it as is so I know for sure this is a different port.

On the clocking/power symbol I placed all power pins one one side and the clocking, reset and jtag pins on the other side.
Attached are also the schematics from my lpc1754 target board, a small target board with USB device, micro-SD, I2C EEPROM and battery backup. The first boards are due to arrive in 1 week so then I'll know if I did a good job

Regards,

Rob

P.s: would it be possible to remove the 19.5 kB limit on a PDF file. It is a bit of a silly workaround to zip PDFs...

[Luis Digital]

Originally Posted by Rob65

The first boards are due to arrive in 1 week so then I'll know if I did a good job

I want a detailed report, with photos included.

[Rob65]

Originally Posted by Luis Digital

I want a detailed report, with photos included.

Consider this done, this is my first big SMD project. I have a bit of SMD reworking experience in replacing stuff as big as a SOT-23 and 0603 devices, I even replaced some 20 mil pitch connectors that were not properly soldered by a vendor. 50 mil stuff I do with my eyes closed (and I have burn marks on my fingers to prove it ).
But a large device like the lpc1754 is new to me. I will manage to do this - and even without loosing one part I hope. Maybe I'll give you a call for some advice

I have already found the first bug ... The 1k5 resistor on the USB_DP line ... that one was placed on the schematics after sending out the PCB data and this is the second time I am forgetting this
And one silly thing in the silk-screen: the pin 1 marker is exactly on top of a via hole and silk screens are not printed on top of vias.
The one thing I did not change ... the LQFP80 footprint from the original library. It also has a full box drawn on the silkscreen to denote the lpc but the lines do run on top of the pads and again; the soldering mask blocks the silkscreen.
A second thing I did not change ... the SOT23-4 footprint for the USB protection diode (just left of the USB connector on the right edge) looks very small, much smaller than the regular SOT-23 on the top left.
Both I copied from existing Eagle libraries.

If only I had listened to my own tips: never trust anything you are given. Always check the footprint of your devices. Always make a 1::1 scaled print out and see if there is anything strange with the footprints (measure with calipers or place the components on the paper to see if it fits).
--- Edit
I meant to write that I did this on purpose just to show how important this all is ...
---

I did perform a netlist check though. Traced all the lines on the PCB to all connections and checked with the datasheets if I have the correct pins.
I also did remember (but only just in time) to place both the pin headers and the mounting holes on a 100 mil grid so it is easy to mount on a (what did Larry call this) perfboard.

Rob

[Luis Digital]

Originally Posted by Rob65

Always make a 1::1 scaled print out and see if there is anything strange with the footprints

I did in my last design, it is a good idea.

Note: For those who never made a PCB "professional", it seems easy, but spent much time, money, and a bit of frustration when something goes wrong, and always something goes wrong.

Selling on eBay? Between eBay and PayPal are up to 2 dollars for a product that costs $14, almost pocket the profit.

And then the buyer does not leave feedback, ungrateful.

Not to mention the Chinese who sell losing money, all to get a point of feedback.