W06 - Electronics Design

1. Weekly Assignments ( -> what I did this week )

  • Group assignment

Use the test equipment in your lab to observe the operation of a microcontroller circuit board

( -> I tested the Digital Oscilloscope and Digital MultiMeter with the group members. )

  • Individual assignment

Redraw the echo hello-world board, add (at least) a button and LED (with current-limiting resistor), check the design rules, make it, test it.

Extra credits: Simulate its operation. Render it.

( -> I made hello-world board adding a button and a LED with current-limiting resistor. Then, I checked the functionality. It worked fine. )

Have you?

Questions from “Fab Academy 2020 Assignments and Assessment

Electronics Design

( -> my answers )

  • Shown your process using words/images/screenshots ( -> yes )

  • Explained problems and how you fixed them, including how you worked with design rules for milling (DRC in EagleCad and KiCad) ( -> yes )

  • Included original design files (Eagle, KiCad, Inkscape, .cad - whatever) ( -> yes )

” 6. Electronics design “

I summarized how to use Digital Oscillosope ( Tektronix TBS 1052B ).

3. Works, steps and some details

1) Redraw the echo-world board on EAGLE CAD

I decided to add one LED and one button.

selected “eagle_fab_lbr” “Use none” for “Managed Libraries”
week06-20 week06-10
add parts selected ATTiny44
week06-30 week06-40
“design Rules” setting “Grid” setting
week06-50 week06-60
line width setting ERC error
week06-70 week06-80
ERC error , and then, fixed one by one component layout on PCB
week06-90 week06-100
design Rules tried “Autoruler”
jumper on the backside of PCB is shown with green color
week06-110 week06-120
“Autoruler” setting “Autoruler” setting ( this was used )
week06-130 week06-140
After thickened GND lines manually, DRC error ( airwire ) were found, but not a big problem blue line shows the jumper on the backside of PCB, so tried to set the holes and via
week06-160 week06-170
relocated the route of jumper so that it can be soldered firmly. hole diameter
week06-180 week06-190
“via” ( to support jumper ) property
week06-200 week06-210
design completed

2) Milling PCB and Stuffing

CNC parmeters for circuit pattern

tool diameter (in) ; 0.0156 (1/64)

cut depth (in) ; 0.004

max depth (in) ; 0.004

offset number ; 4

milling speed ; 4 mm/s

mods to create the circuit pattern ( “dpi” needed to be changed from 800 to 1600, to fit the proper scale. This might be depending on the MacBook Retina display. )

CNC parmeters for holes and outline

tool diameter (in) ; 0.0312 (1/32)

cut depth (in) ; 0.024

max depth (in) ; 0.072

offset number ; 1

milling speed ; 4 mm/s

mods to create the holes ( also, “dpi” 800 -> 1600 )
pattern.png jumper holes ( milling.png )
pattern milling
milling the plate
unnecessary portions were removed
week06-244 week06-246
after stuffing the components
( added the black mark for GND )
jumper, backside
week06-340 week06-350

3) Functional Check

A. echo program

I downloaded “hello.ftdi.44.echo.c” from fab academy site, and implemented using the commands below, referring the site below.

12. Output devices : fab academy 2019 Rico Kanthatham

make -f hello.ftdi.44.echo.c.make

make -f hello.ftdi.44.echo.c.make program-usbtiny-fuses

make -f hello.ftdi.44.echo.c.make program-usbtiny

downloading “hello.ftdi.44.echo.c” implementation
week06-240 week06-250
selected “Serial Monitor” in Arduino IDE port setting
week06-300 week06-310
115200 baud rate It worked fine! ( but put PCB on the aluminum body of MacBook might “not” be a good idea )
week06-320 week06-330
LED on-off switching test
week06-360 week06-370

B. LED on-off switching program

I downloaded and implemented the program file “LED2.c” from the site below.

And, it worked fine.

9. Embedded programming : fab academy 2019 Kae Nagano

4. Important Learning Outcome

1) GND design on PCB

In order to avoid the possible problems regarding the ground lines on PCB, I decided to use jumper on the backside of PCB, also manually thickened the GND lines.

The PCB worked fine, although whether it was because of the above decision or not, I think this is a safer way especially for more complicated PCB design.

2) EAGLE “Autoruler”

This function helped me a lot to save time. I’ll explore this function more precisely.

EAGLE CAD files :

week06.sch download

week06.brd download

.png files :

pattern.png download

milling.png download

outline.png download

.rml files :

pattern.png.rml download

milling.png.rml download

outline.png.rml download

“echo hello” files :

hello.ftdi.44.echo.c download

hello.ftdi.44.echo.c.make download

6. Appendix

12. Output devices : fab academy 2019 Rico Kanthatham

9. Embedded programming : fab academy 2019 Kae Nagano