Week 4 - electronics production

Make the FabISP in-circuit programmer

Posted on February 25, 2015

What do I need to do this week?

  • Customize my board (02/19)
  • Milling (02/19)
  • Stuffing (02/20)
  • Programing (02/23)
  • Customize my board

    Software used:
  • GIMP
  • I decided to make the Neil FabISP version because in my opinion the USB connector is more stable than a pendrive model. Here's how it looks like:

    So I made two modifications in PNG file with the milling traces, first I changed the MIT logo to my logo, and second I removed the white border to reduce the milling time because this trace will be cutted in a second step. Here's the result:

    Milling

    Software used:
  • Fab Modules
  • Machine used:
  • Roland MDX 20
  • Tips:

  • Make sure that your image has the right DPI resolution and size in cm. You should also check the image size in Fab Modules before send it to cut, as you can see in the picture below.
  • Before start to milling your board you should run the outline file ("interior.png"), to make sure that Z alignment is correct. So set Z as 0 and send it to cut.

  • After the Z alignment I loaded the PNG file with my logo and adjusted the settings in Fab Modules to sent it to cut.


    FAIL: I had exported the PNG file with 72 dpi and the original file has 1269,448. Basically the image size became bigger and the machine went to a different position from the previous origin and started to cut.

    So I had to export a new PNG file and set the Z alignment again. Here's the final milling result:


    Stuffing

    The first step was to separate all the components. To make sure that I wouldn't mix everything I used a double sided tape beside the components list:

    Tips:

  • Check if the iron's tip is clean, if it's not, clean it with the wet sponge.
  • Don't let the iron on for too long without use because the tip starts to oxidize.
  • Double check if the components are in the right orientation.
  • A good tip to weld is heat the copper board and the component first with the iron and then insert the solder, because if this set are not in solder melting temperature it won't weld well.
  • If the solder doesn't become shiny, probably means that you didn't heat enough the set, so you could try to heat it again and put a little bit more solder.


  • FAILS:

  • I wasn't aware and I did solder the second diode on the wrong side.
  • I changed the position of two components with similar appearance in my list, then I soldered it in the wrong position.

  • What I did to solve it?
    Unsoldered these two components just heating the solder points with the iron and pulling with tweezers when the solder got in melting point, then I soldered again in the right position.

    Programing

    After soldering process I took risk because I pluged the board directly to my computer USB port, and after that I discovered that if something was wrong I could burned my board or my computer. Fortunately everything was fine, and my board is working. So, I did the tutorial for programing in MAC and I had one problem with Xcode installation, it didn't work in my computer. Then I decided to start programing without the Xcode to see what would happen, and what happened was when I did "make clean" command it asked for a software to be able to make the command and also asked if I would like to install it. I chose YES and after a few minutes it was done and I could finish the programing without problems.



    week 3 / computer-controlled cutting week 5 / 3D scanning and printing