part arrangement

Discussion in 'General Electronics Chat' started by mik3ca, Feb 14, 2008.

  1. mik3ca

    Thread Starter Active Member

    Feb 11, 2007
    189
    0
    I'm making an 8051 SBC system, but I have one problem.

    Many of the circuits involve using double sided circuit boards.
    I want to only use single-sided board, because I only have a single-sided board, and I don't have the resources to do it (like an expensive machine).

    I bought myself special jumper blocks which are shaped and wired exactly the same as a block of 5 dip switches stuck in the ON position. I only have two of them right now, and I plan to buy more later if necessary, but I want to minimize the need of them which is why I am asking for assistance.

    If anyone has made a SBC on a single sided board, tell me your thoughts as well, because I'm sick of trying to arrange the circuit properly.

    There must be a good reason why they label the pins the way they do.

    My EEPROM is: AT28C256
    My CPU is: 80C51-BH
    my RAM is: CY7C185

    Since I have at least two of each part, I want to use them instead of throwing them out in the garbage.

    I'm sure there is a technique for chip placement. and I want to avoid dangling wires. I just want to use my jumper blocks as my wires so that the board looks more professional when it is finished.

    Thanks.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It's going to be mighty tough to make a SBC on a SS PCB. You're going to need LOTS of jumpers on the top of the board, and it's going to be really awkward. You might find it easiest to arrange them in a row, so that you can run data bus/address lines both outside of and inside of the DIP's legs.

    I don't have your EEPROM nor RAM in my libraries. What are you using for schematic capture and PCB layout editor?
     
  3. mik3ca

    Thread Starter Active Member

    Feb 11, 2007
    189
    0
    Eagle is my schematic software because Eagle has an autorouter.
     
  4. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Save yourself the headache and frustration and buy a double sided PCB. www.33each.com lets a student buy a single 60 square inch double sided PCB with fine traces, along with soldermask and silkscreen for only 33$.

    Steve
     
  5. mik3ca

    Thread Starter Active Member

    Feb 11, 2007
    189
    0
    I want to be able to buy my own PCB and make it myself. I have made my own PCB's bebore when I made my radio circuits. sometimes, thinking outside the box is better.

    and since I have a few single sided PCB boards, I want to use them
     
  6. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    In this particular project, I fear that thinking outside-the-box is going to lead to dissappointment and ruin.

    If you are serious about this effort then be prepared to use a large quantity of jumpers, 0-ohm through-hole or surface mount packaged resistors.

    hgmjr
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    If you have access to 30 ga insulated wire, then you can arrange the jumpers on 50 mil centers. it generally works best to have traces on one side go all horizontal, and all vertical on the other.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If you're dead set on using your single-sided boards, then I suggest you put a thin, even layer of epoxy over the top of one of the single-sided boards, and stick the top of another single-sided board to it, and clamp it together using a LOT of pressure so that you then have a double-sided board.

    Or you could save yourself that headache, and buy some nice double-sided FR4 board stock.

    Marlin P. Jones & Associates just happens to be having a sale on 12" x 12" double sided 1oz copper clad board, $8.95 each.
    http://www.mpja.com/products.asp?dept=393

    I've bought from them a number of times over the last 10 years. I recently bought a couple of these boards from them and paid several dollars more, they were still a good deal.

    Etching double-sided boards and then drilling all the holes is problematic and takes a lot of patience. Prepare to wind up with lots of scrap pieces of fiberglass FR-4 board material.

    Autorouting, although seemingly convenient, is not necessarily the best way to do things - particularly when dealing with high speed address and data busses.

    Make sure you use plenty of bypass caps, and use termination resistors on your buss/address lines according to specifications. Look for application notes on the manufacturers' websites.
     
  9. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    An addition to the above - I hope you have a high speed drill made for pcb work, along with extra carbide drill bits. Drilling FR4 eats steel bits very fast. Drilling 1/8 thickness FR4 will be difficult. Be prepared to itch - the fine fiberglass fuzz is very irritating.
     
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