5. Electronics production

In this week of FabAcademy, we start using a milling machine to produce PCBs. Also we learn the basics of soldering electronics onto the PCBs.

Group Assignment

As a group assignment, this week we have to test our milling machine and characterize the design rules for our PCB production process.

In-Circuit Programmer FabTinyISP

Milling

For the production of an in-circuit programmer, I went along with a tutorial you can see here.

I download PNGs for the traces as well as the outline cutout from the tutorial website and visit FabModules.

Here i import the PNG and set the output format to .rml (since we have a roland mill in Kamp-Lintfort).

For process i choose PCB traces (1/64) and choose the Roland MDX-40 as the output machine.

I set the x and y to 0 and eventually change the tool diameter.

I repeat this process for the outlines and choose PCB outline (1/32) for process instead.

I set the tool diameter to 1mm and save the results.

Afterwards I go ahead and open the software to control the roland mill. Therefore, we have a laptop next to the machine in Kamp-Lintfort.

Firstly, I have to set the machines coordinates to be able to cut perfectly. Changing the x and y is fairly easy, but getting the right z-coordinate is a little harder:

To ensure that the tool is barely touching the PCB, we take a multimeter and check if there is a connection between the tool and the PCB. If I hear a beeping noise, we are good to go. But you have to be very careful not to harm the tool!

Soldering

Luckily, everything went well in the first try, so we have a nice PCB from the milling process. Next, I gather the parts I need to solder onto the PCB and go on to the soldering station.

  • 2x 1kΩ resistors

  • 2x 499Ω resistors

  • 2x 49Ω resistors

  • 2x 3.3v zener diodes

  • 1x red LED

  • 1x green LED

  • 1x 100nF capacitor

  • 1x 2x3 pin header

After soldering the parts I can test if it is working by pluging it into a USB-Port. Therefore, it is better to use an external USB-cable, so the PC’s ports won’t take any damage.

For a first test, I use a multimeter to check if the connections are alright and all the components are soldered and are positioned correctly.

If everything went well, the red LED should lighten up as soon as it is plugged in.

My board looks quite fine, I’m very satisfied with the result.

DOWNLOADING SOFTWARE

After installing the essential software for programming as described in the tutorial mentioned above, I need to download firmware source code as provided in the tutorial, too.

INSTALLING

Afterward I use GIT bash to navigate to the directory of the source code and run the following commands:

I start off with “Make”, to create a .hex data I need for programming. Afterward, the following commands are needed:

Lastly, I need to connect a programmer to programm the empty microchip. I connect the via a ribbon cable and finally program it.

TEST -> DEVICE MANAGER

In the last step, I check if everything worked by plugin my board into the computer. I visit the device manager and see if I can find it:

The FabISP was successfully identified by the computer and after removing the bridge essential for programming the board, I can use it as a programmer!