Custom arduino Design WITHOUT ISP header?

Community PCB Design
1

I’m designing a custom Arduino project, and it’s annoying me that I have to stick an AVR-ISP header on the board, even though I’ll only use it once (to put the Arduino Bootloader on there). Once the bootloader is on the chip, I plan to only use an FTDI cable header to upload sketches, etc.

Has anyone had experience desiging custom Arduino boards? Is there a way to do this without the AVR-ISP header?

Or is there somewhere I can get a bare AtMega168/5V/20MHz in TQFP package with the Arduino bootloader preloaded?

2

roach:
I’m designing a custom Arduino project, and it’s annoying me that I have to stick an AVR-ISP header on the board, even though I’ll only use it once (to put the Arduino Bootloader on there). […]

Has anyone had experience desiging custom Arduino boards? Is there a way to do this without the AVR-ISP header?

Depending on whether your issue is with allocating space for the header or with having the header physically attached:

  • - You could use "pogo pins" or similar and just the ISP footprint on the PCB for a "press to program" solution. But you could get somewhat similar results just by removing the physical header once the chip was programmed. I did something close to this with a board I made once.
  • - Another option is to take a similar approach but have the portion of the board with the header be able to be snapped off.
  • - A third option would be to use pogo pins or similar in a jig which fits over the TQFP and connects with individual pins to program it--I'm not sure how easy this is to do in real life though.

    • –Philip;

    3

    follower:
    Another option is to take a similar approach but have the portion of the board with the header be able to be snapped off.

    Hey, I like this. I was just going to solder some wire-wrapping wire onto the ISP pins of the controller, program it, then remove the wires.

    How can I go about doing this “snap-off” thing with BatchPCB?

    4

    There are TQFP sockets that you could use to build an adapter for flashing the bootloader before soldering the AVR to your board. They can be rather pricey though ($50 to $100+). Either that, or a programming fixture which uses pogo pins to make contact with pads placed on your board for the purpose (as suggested by follower), is generally how it’s done in commercial mass production.

    To make a snap-off portion of a PCB you would generally use slots and/or a row of closely spaced holes (with your ISP traces routed between the holes). I’m not sure how well BatchPCB would handle something like that - my experience with them is limited to plain rectangular boards.

    5

    tesseractor:
    To make a snap-off portion of a PCB you would generally use slots and/or a row of closely spaced holes (with your ISP traces routed between the holes). I’m not sure how well BatchPCB would handle something like that

    I suggest the OP check out viewtopic.php?f=16&t=20770 and http://batchpcb.com/index.php/Faq#Can%2 … c%20shapes then email BatchPCB to ask directly. :slight_smile:

    –Philip;

    6

    tesseractor:
    To make a snap-off portion of a PCB you would generally use slots and/or a row of closely spaced holes (with your ISP traces routed between the holes). I’m not sure how well BatchPCB would handle something like that - my experience with them is limited to plain rectangular boards.

    My suggestion would be to have the board house V-Score this part of the board, except a small section that you can run traces through. Then just snap it off clean. If the edges bother you, a little sand paper and a block will fix that.

    7

    Thanks everyone for your suggestions! I ended up going with a straight “no header” design. I’ll temp-solder some 30 AWG wire directly to the chip leads once it’s in-circuit, then remove them once the Arduino bootloader is flashed.