This week are assignment is to redraw the Echo Hello world plus board in Eagle and generate a PNG file suitable for milling. Once created the PNG, mill out board and test it by uploading a program on to it.

Here is the image of the board that we have to recreate:

The overall build of this board consist of:

• 1x ATtiny44
• 1x 10 KOhms resistor
• 1x 1uF capacitor
• 1x FTDI header
• 1x ICSP header
• 1x LED (Light Emitting Diode)
• 1x 1KOhms resistor
• 1x 20MHz resonator
• 1x Button

Drawing Board

Before I start drawing the board on to EAGLE, I first installed a package from this guide called Drawing a circuit in Eagle. Within this guide it was recommend to download this link, which contain most of the components that is needed for this build.

Once downloaded, I ensured to move the file into where my Eagle Library is located in my PC. Which i then open the Eagle Control panel, find the library I have added and select it to use.

I then went and started adding components that is required for this build, on to a new schematics in Eagle. This is done by going in to”edit” and press “Add”.

To ensure that I have added the right components into the schematics. I check the image display on the right of the add window when selecting the component and refer back to the image of the board that we have to recreate.

I found this quite tedious as well as annoying to do. as the components may differ or not be the same as the original board. which makes it harder to check if you got the right part.

Once I added all the components onto the schematics, I finally went and rearrange the components and linking them together using the “NET” tool as well as using the “Junction” tool when multiple Nets are connected to one net. The Schematic is the logical structure of a circuit, and how are the components are connected. The green lines show the connections between components. Where the Red lines are the components.

After connecting the components in the schematics I went in to the board layout. This is done by pressing “BRD” button in the tool bar. Board layout is a visual representation of the board, also where the components go on the board, and how to route traces connections between the components. The yellow lines presented are “airwires”. So in this step I have to rearrange the components so that the traces being applied isn’t clustered and messy. As well as convert the “airwires” into traces. while making sure the width of the traces is 16 mil.

within this step I also rename and revalue each part respectively to the original board.

Before

After

After rearranging and converting the “airwires” into traces. i went and check the clearance of the traces by going into the “tools” menu and selecting “DRC” and setting the clearance of everything to 0.4mm ( this will be the size what the board will be milled out). From this I have found that my board has multiple errors along many traces.

I then went and redid/ arrange the traces where the error has been displayed and checked it again, here is an image showing no errors found:

After showing promising sign i then went and exported this as a DXF file which ill then open in adobe illustrator in preparation or milling. Once extracted as a DXF file and open in illustrator I went and edited and removing any layers that are not necessary. I then made sure the strokes of the traces and the pads of the components are black as well as the outline of the art board surrounding it is black.

Before

After – Board

After – Art Boarder

After converting the colours of the board into black and white. I then went and exported it as a PNG file making sure to “Use Artboards”, and Making the PPI is at its highest so i set mine to 1000 PPI.

Once i exported it and saved it as a PNG, I went into Photoshop where I inverted the colours of the traces and the pads of the board.

To test if the parts fit on the board before I milled it out, i went and printed the board out onto paper. However when printing the board out as an PNG the size of it was too big. So i went back into adobe illustrator and printed it from there which printed it to the right size.

I then gathered all the components from the Fablab and start arranging the components onto the paper print out. From this, the FDIT header part was too big for pads on the board design, so I made the pads where the FDIT header is more wider from 2.5mm to 5mm in adobe illustrator. By making the pads more wider, it will help secure the FDIT header in place once soldered onto board. I went and exported the board as a PNG again.

Milling

I went and imported the PNG image of the board design into fabmodules.org making sure the output format is “Roland mill (.rml)” and the process is “PCB traces 1/64” however for the boarder it will be “PCB outline 1/32” This website was used to help create and prepare the tool path for the CNC milling. To check if the traces on the board is suitable and has no problem creating the tool path. I had to adjust the setting on the website by setting the offset to one. From this i have found many problem with the tool path where some traces have merged together.

I redid did and altered the layout of the board design in adobe illustrator and exported the new design as a PNG and imported it into fabmodules.org where I checked it again. Once there is no problem with the tool path and that the traces of the board does not merge I am ready to mill out my board design. To ensure that my design was ready to be milled out i checked the setting of the tool path is as follows:

Output:

• machine = MDX-40
• x0 (mm) : 0
• y0 (mm) : 0
• z0 (mm) : 0
• xhome (mm) : 0
• yhome (mm) : 0
• zhome (mm) : 10

Process:

• Tool diameter (mm): (board design = 0.4mm) and (Boarder = 1mm)
• Number of offset: (board design = 3) and (Boarder = 1)

and leave everything else as it is. i then saved the tool path and proceed to the next step.

To set up the CNC,  I first placed a new … on to the base and secure it using double sided tape making sure that the … is in line and parallel to the base. Once positioned, i made sure to use the right tool bit which will be the 0.4mm to mill the board design. I then went and set where the origin making sure to be careful not to break the tool bit when adjusting the z axis. Once origin is set, i finally output the board design to the CNC. Here is the outcome:

Here the board with all the components/ parts soldered onto the PCB: