Electronics production


Assignement for this week is
• group assignment: characterize the design rules for your PCB production process
• individual assignment: make an in-circuit programmer by milling the PCB, program it, then optionally try other PCB processes
First of all I took user manual of Srm-20 milling machine and started learning how operate it. Fab ISP (In system programmer) is designed in fab lab and it is another version of an AVR programmer.
I should do the following actions:
• set up the machine for milling process
• prepare files for milling, I will use fab modules
• cut the board
• solder components
• programm the board

Setting up

• Turn on the machine
• Put the material in the machine, fixed it with double sided stick
• Attached end mill 1/64 for milling traces
• Opened fab modules and upload my files there, then saved
• Setted the origin point chose"[Machine Coordinate System" in our case will use "G54" and "G55" that's the first 2 of 6 Work Coordinate Systems. During this process I used Vpanel pointers "right" "left" "up" "down"

Picture of endmills I used (1/64 and 1/32)

• Went back to fab modules and chose image "png"- Gcode "nc"-PCB traces "1/64" - "selected calculate" - "save"
Fab Isp traces

Fab Isp cut out

• Opened "cut" on vpanel and chose the cut file "Fab Isp traces" and start cutting

• When the traces were cut I repeat the process in fab modules for cuting out the the board, but that time I chose PCB traces "1/32"
• Cut out the board and cleaned up.
But after cleaning up the board I found out that the milling process had been failed, as parly the board was not milleed properly So I had to mill it again and set the "x,y,z" points again. The second try was successful.


I have never soldered smd componets before, that's why I was very excited to do it.
• Turned on soldering iron
• Selected the componets
• Started soldering of course I did many miastakes and demaged my fingers
• Cut another one board, as I demaged the first during soldering process. This process I repeated 3 times. The copper surface was striped.
• Finally I soldered all components

I used the following components
• ATtiny45
• 1k resistors
• 499om resistors
• 49om resistors
• 3.3v zener diodes
• 100nF capacitor
• 2x3 pin header

Now the board is ready


• Connected AVR programmer
• Opened the terminal
• Wrote the command "sudo apt install avrdude gcc-avr avr-libc make"
• Downloaded firmware source code file
• Extracted firmware files
• Cd to the folder and write "make" command
• Then updated "makefile" with USB name, for that, run "gedit" in terminal, opened makefile in the firmware folder, edited the name "usbtiny" to "avrisp2". Finally saved the file
• Ran command "make flash"
• Ran "makefuses"
• Removed AVR and Attiny45 board, and pluged in Attiny45 board again
• Ran "lsusb comman", it showed ".Bus 001 Device 009: ID 1781:0c9f Multiple Vendors USBtiny"
Then removed AVR and TinyISP from system and insert it again in USB port, and my ISP did not work. I checked all connections by multyeter and foun odut that the controller did not work. I had to cut and solder the board again and this time I soldered it by lower temperature. Repeated all actiones described above and my ISP worked.


During this week I learned a lot of new things about
• SRM-20 machine operation and milling
• Endmills, I read a lot of about different type of them
• PCB design
• Soldering SMD components
• Programmers and programming
And got painful injuries during soldering and learned about safety norms․
I needed to have Fab ISP in properly working condition as I would use it during next week for programming electronics board.