Did I just make a green coaster?

Community PCB Design
1

Can someone familiar with the LPC210x look over my PCB design and tell me where I went wrong?

here’s the SVN for the eagle project:

http://www.realityshards.com/eagle/eagl … 210x_dust/

(lpc210x_v1d.zip is the one I submitted to BatchPCB).

I have made an attempt to create a breakout/dev board for the LPC2103, I know there are others out there but I want to create one for myself so I have a foundation for other projects that will have that chip on board, and because I was more interested in the SPI and I2C connections then anything else as most of the projects I have will be connecting a whole string of components using those busses.

I have a friend who does plenty of PCB and SMD work and consulted with him for much of the standard PCB/SMD issues and decisions, but as he worked with AVR chips he had no input for the requirements of the LPC and if I was meeting them properly.

The situation now is that I decided to go for it and put an order in for a couple of the boards, ordered all the parts, and put it together… and got nothing.

I have double checked all the pins, I’m getting power where I want power, I’m getting ground where I want ground (after soldering a wire to pin 19, for some reason the PCB didn’t run that connection). I’ve checked all the other pins and made sure they are going where they should, checked for solder bridges and there are none.

I’m getting 1.75v for the 1.8v inputs (within good limits) 3.2v on the 3.3v input (again within good limits), the DBGSEL and RST pins are pulled high, oscillator output is looking right.

I’m using the olimex ARM-USB-TINY from spark fun to connect to it. I’m getting “JTAG scan chain interrogation failed: all ones” (OpenOCD 0.6.0, installed on OSX 10.7.4 using MacPorts, using the following command: “openocd -f olimex-jtag-tiny.cfg -f lpc2103.cfg”, with the lpc2103 config adjusted to a 10Mhz clock).

So, the question is, where did I fail?

Some notes that I will be working on for round 2 (if I can figure out and solve the faults for round 1):

  • 100uf cap on supply input: I couldn’t find a ceramic cap for that footprint and rated more than 6.3v, so it’s empty right now… I will be updating it to a can on the next revision.

    Reset button: I don’t know why I decided not to put one on…

    Bigger resisters on the LEDs… those things are bright.

    Make more use of the underside of the board… I’ll be using standoffs and a project box, I don’t care what’s there…

    Post for grabbing the ground, from the scope to the voltage tester it’s just easier then holding the ground to some cap…

    • I would be very grateful for any assistance, and once I have a PCB design that actually works it’ll be up on BatchPCB marketplace with the BOM from digikey and links to the eagle schematics/etc so others can play with it as well.

    Thank you for your time!

    Erik

    2

    It seems to have quite a few errors. Check it against this Olimex schematic:

    https://www.olimex.com/Products/ARM/NXP … 03-sch.gif

    I’ve got a Silica LPC2103 board that was made by Olimex, and the schematic is similar.

    3

    Differences I see, which ones are errors are another question, and one I can’t seem to figure out.

    also, I based the design to be closer to this reference design as it’s fairly high on the list when google searching “lpc2103 reference design”

    http://www.microbuilder.eu/Images/Proje … ematic.png

    Two of the big differences I can see is that I don’t have the analog power and ground connected as I hadn’t been planning on using them… however I’ve started to reconsider that…

    secondly I don’t have a clock hooked up to RTXC1 & RTXC2… if I read the manual correctly those are only used as an alternate clock for the Real Time Clock, and is not used for the bus clock. (page 69 of LPC2103 user manual note 8 “For lowest power consumption, pin should be left floating when the RTC is not used”)

    I’m sorry, but saying there are errors doesn’t help, I can tell that by it not working… I need someone to point out what the errors are, and maybe why, so I can go and fix them and get an understanding of how to make a board that works.

    Thank you though, I will be looking at the schematic you linked, comparing it to the other reference design and to what I put together and I’ll try to figure out what is going on.

    Erik

    4

    Just copy a working schematic. Here is a design of mine for the similar LPC2106:

    http://sd2cx1.webring.org/l/rd?ring=cir … _heller%2F

    You don’t need the RTC connections.

    You will probably get more help from the LPC2000 group:

    http://tech.groups.yahoo.com/group/lpc2 … =293062608

    5

    More than likely you have to supply power to the analog section even if you don’t use it. Try “blue wiring” power to the supply pins and see if it works.

    6

    Tried that no change, analog power and ground are both connected and no change with the processor.

    Can someone please tell me what is wrong?

    7

    It doesn’t look like the Reset pin is pulled up on your board.

    8

    Wow… that was a dumb mistake… :oops:

    Thanks a ton for the catch! I’ll be testing it this weekend to see if that’s the big problem holding me back! :slight_smile:

    hickorystick:
    It doesn’t look like the Reset pin is pulled up on your board.

    9

    Thanks a ton hickorystick, that was the answer, pulled it to +3.3v and JTAG started talking!

    Thank you very much for answering my cry for help!

    Erik