LPC11U24/LPC11U37/LPC1347 RF Board

Posted by:  |  Wednesday, July 25, 2012

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I've been looking for an excuse to do something with the LPC1347 for a while, and I ended up recycling a lot of previous work, combining a number of lessons learned into a single four-layer board that should let me test a number of power supply and project scenarios.  I kept the board fairly basic, just a microSD card for datalogging, USB, and SWD connector, and reset/ISP buttons.  There's on on-board user-selectable 3.3V/2.2V linear regulator (TPS780), but it can be bypassed and you can power the board from another source for flexible power input and current control.  It's designed to fit in these inexpensive weather-proof cases with a transparent top for a small solar cell, but should be easy to adapt to another enclosure.

I kept the RF section completely seperate as well so that I can change to another chip if required.  The current board uses an AT86RF212 (868/915MHz 802.15.4), and I can drop in an AT86RF230/231 (2.4GHz) with a simple adjustment to the transmission line width for impedance matching ... but I also whipped up a schematic for the nRF8001 for Bluetooth LE that I might test down the road.  The way the board is now I can make seperate 2-layer add-on PCBs for various power and sensor inputs, sticking to one common footprint and header to evaluate things more quickly.

One benefit of the ARM Cortex M3 based LPC1347 is that it's pin compatible with the Cortex M0 LPC11U24 and Cortex M0 LPC11U37.  This gives me a decent selection of options between price/performance/flash size on a single PCB, with minimal SW changes, all of which have excellent power numbers:

  1. the LPC11U24 is dirt-cheap - 50MHz M0, 32kB flash, 8kB SRAM
  2. the LPC11U37 has lots of flash for complex stacks - 50MHz M0, 128kB Flash, 8+2+2kB SRAM
  3. the LPC1347 is a high-performance chip with a decent amount of flash - 72MHz M3, 64kB Flash, 8+2+2kB SRAM and 12-bit ADC

It's just a personal, weekend project, but I'll blog some more about this board when I get the PCBs in later this week since it was a big (if expensive) learning experience.  Here's some photos of the PCB being manufactured, though, if you've never seen the different steps of the process (courtesy PCB Pool):











Tags:  Cortex M3 RF Cortex M0 802.15.4 NXP LPC1100 NXP LPC1300

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Comments  (17)

  • Fede

    7/30/2012 12:00:00 AM

    Very nice!!
    Excellent layout!
    Just wondering, that little metal cage, where did you get that?

    Keep posting!
    Regards
    Fede

  • Alex Mastro

    7/31/2012 12:00:00 AM

    Nice work, as always.

  • microbuilder.eu

    8/1/2012 12:00:00 AM

    Fede:

    They're from Laird ... you can get them on Mouser, and perhaps some other distributors.  The two part cages are nice since you can reflow the base with the rest of the board, but still fix any solder joints, etc., and pop the cap on before shipping.  They cost a little bit extra, but I like not having to brutalize a board to get at the RF section.

  • Phang Moh

    8/7/2012 12:00:00 AM

    Is that immersion silver finish on the board?
    I like the RF shield as well else 2 time reflow would definitely hurts he component a little.

  • Alex Mastro

    8/22/2012 12:00:00 AM

    Any chance publishing an update on the microbuilder EAGLE library?

  • microbuilder.eu

    8/24/2012 12:00:00 AM

    Alex:
    Updated.  It has been a while, but I didn't update because I've switched to Eagle 6.0 and the library is no longer compatible with previous versions of Eagle.  As always, there are no guarantees and some of the footprints haven't been tested in production (notably the QFP64 and QFN33 1347 packages).

  • Linus

    8/28/2012 12:00:00 AM

    Hi

    great project. I am highly interested in this design, can you possibly make it available?

    Thanks
    Linus

  • microbuilder.eu

    8/30/2012 12:00:00 AM

    Linus: It's still in development and there are some HW issues that I'm still working out so it will take a bit of time to vet the design.  There's at least one more revision before I'm willing to release the schematic into the wild anyway, just no to mislead anyone since as soon as you publish something it takes on a life of it's own.

  • JF

    9/5/2012 12:00:00 AM

    Hello,

    Very interesting !

    >>schematic for the nRF8001 for Bluetooth LE
    How could i get the schematic?

    Thanks,

    JF

  • Alex Mastro

    9/7/2012 12:00:00 AM

    Thanks for the EAGLE library update - really helpful.

    Have you been using CMSIS for these new chips that you've started to work with, or have you written your own headers?  That lack of NXP-supplied bit-names is killing me.

  • Sebastian

    9/12/2012 12:00:00 AM

    Hi,

    is there a sample project template for the lpc1347 anywhere ? 

    especially a ldd script 

    thanks
    sebastian

  • microbuilder.eu

    9/13/2012 12:00:00 AM

    Alex:

    I actually need to push a new update since I found a few issues with the current library, but it will likely be next week before I push a new version.  I've been using CMSIS myself.  I've been defining some bits myself for certain peripherals, but just can't afford to put as much time into things as I was able to with the 1343 and 1114.  That was a pretty crazy amount of work putting those headers together by hand from the UM, but on the positive side it was a good way to get a really good overview of every peripheral on a new chip.  I just can't see the point of swimming against the current and not using CMSIS moving forward, but if I make some additional header files I'll post them.

    Sebastien: 

    I'm still doing all my early development in Crossworks while I try to bring all the peripherals up.  Looking good so far since I have all the main peripherals working, and made some improvements to the older code (better error handling, localized text, etc.) ... but haven't dropped down to a Makefile yet so no linker script.  What you can do though it create an LPCXpresso project (free) and just look at the auto-generate linker script and make files to get you started?

    It's going to take me some more time before I publish my own codebase since I'm still not happy with some of the code, and I haven't even touched USB yet.  The power numbers are a bit higher than I'd like (30µA at 2.2V) and there's something going on in SW there that I need to figure out.  The transmission line on the RF section is pretty poor as well and really need to be recalculated or tuned, but I'll have to rent a VNA to properly measure.

  • Alex Mastro

    9/13/2012 12:00:00 AM

    I hear you on that - those headers must have taken a ton of time.  They were great for helping me get started with NXP LPC chips. 

    I've switched to CMSIS, myself as well - because of the reasons you listed.

  • Sebastian

    9/13/2012 12:00:00 AM

    Hi,

    git it working.

    you will find the code here: https://github.com/sebseb7/pentarm13uxx

    contains a small template project (blinking leds) including Makefile and linker-script

    the repository also contains eagle file for a small lpc1347 eval board.

    /sebastian

  • Sebastian

    9/14/2012 12:00:00 AM

    I tried hw_usb_cdc in a separate branch, and it seems to work. With the default packet size of 64 I get 0.5 megabit per second duplex.

  • microbuilder.eu

    9/15/2012 12:00:00 AM

    Sebastien:

    I'll have a look ... I spent a couple hours trying to get the ROM-based CDC example working but it wasn't instantiating properly, though it could be a dozen things and I didn't pull the USB analyzer out to really dig into it.  It's at the top of the ToDo list, though.

  • Leon

    10/6/2012 12:00:00 AM

    microbuilder.eu:

    We would like to experiment along with you on this design (especially LPC11U37). Let me know where we can help? RF design optimization? Seperate link / Makefiles, etc? Contiki port?

    Cheers,

    Leon.
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