4. Electronics production¶
Individual Assignment¶
- Make an in-circuit programmer that includes a microcontroller
- Customize the design.
- Mill and stuff the PCB
- test it to verify that it works (extra credit: try other PCB processes)
Group Assignment¶
Characterize the design rules for your in-house PCB production process link to group assignment
For this week I used the Roland SRM-20 PCB milling machine and the V-panel for SRM-20 software.
This week we are to mill a Fab ISP(In system programmer) and program it to be used as a programmer for the Fab Academy course as we are not allowed to use other programmers. So to begin with we were provided with already designed Fab ISP board by Fab Academy, all I had to do was download it and the mill and program it accordingly.
We were given the liberty of designing the routing as we found fit but I didn’t edit anything, simply downloaded the design for milling.
You can download the png file of traces of the board from here and the outline cut out png from here.
The schematic version, traces and outline png images are given below;
Using Mit Mods to make .rml files¶
Next up, you have to go to MitMods and follow the following process to upload the png files for conversion to rml(redline markup language) format.
You upload the png file as shown below;
I uploaded the traces png first and selected mill traces(1/64) since it’s for the traces and you press calculate to generate the tool path for the machine.
The tool path looks something like this.
Next you delete the web socket as shown here.
To save the module you have to right click>> modules>> open server module>> save as shown below.
Now you have to connect the input file with the output file by simply clicking to input file and clicking to the output file of Roland SRM-20 and they will be connected.
After doing so you have to again calculate the toolpath by going back to ‘mill raster 2d’ and pressing calculate. By doing so the rml file will automatically get downloaded.
Now for the outline, you just have to follow the same steps except for one, that is, in the ‘set pcb defaults’ you have to select mill outline(1/32) since its for your outline and after that the same steps till you generate the rml file.
PCB milling¶
Once we are done with the rml file generation, we have to upload that file to V-panel for SRM-20 which is the software used to input files to the machine and in return the machine does the milling with the given tool paths. The following image shows the control buttons of the software.
To upload the rml file, you have to press on cut>> add>> open the rml file. Next up set the x, y and z coordinates. Once you are done you have to use 1/64 end mill for the traces and change it to 1/34 when cuting the outline. Next up you have to do zeroing where you loosen the end mill and make it to touch the copper board and then tighten it up. In the following image you can see me doing the zeroing for the 1/64 end mill.
Once done with the zeroing process you have to push the output button to make the machine start the milling process.
Once the milling is complete, you take out the base out and use a scrapper to take out the cut pcb out from the copper board.
Soldering¶
Soldering is a process of joining two or more different types of metals together by melting solder. To stuff the components to the pcb we use soldering. So before I started soldering I gathered all the components from the fablab inventory and started by soldering the resistors first but later on I was adviced to start by soldering the header pin first.
The following images shows the process of soldering.
The soldering iron in the fablab.
My final soldered Fab ISP
Programming the Fab ISP¶
To program the Fab ISP, we used Atmelice isp to program the Fab Isp. You have to connect the Fab Isp to the Atmelice isp and then connect it to to your desktop. The red led must light up which signifies that the power is working.
Firstly you have to download the firmware source code which you can do by going to fab academy website here. I used Ubuntu operating software to program the board.Once the zip file is downloaded, you have to extract the files from the zip file.
Once you are done with the extraction you can open a terminal and cd to the source code. Inside the file we run makefile and then we have to edit the makefile such that the programmer is changed to atmelice_isp. Then we have to run the make in the terminal from the AVR folder.
Next use make flash.
Next use make fuses
