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 )

2. Group Assignment Link¶

” 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”

add parts	selected ATTiny44

“design Rules” setting	“Grid” setting

line width setting	ERC error

ERC error , and then, fixed one by one	component layout on PCB

design Rules	tried “Autoruler” jumper on the backside of PCB is shown with green color

“Autoruler” setting	“Autoruler” setting ( this was used )

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

relocated the route of jumper so that it can be soldered firmly.	hole diameter

	“via” ( to support jumper ) property

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 )

	milling the plate

	unnecessary portions were removed

after stuffing the components ( added the black mark for GND )	jumper, backside

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

selected “Serial Monitor” in Arduino IDE	port setting

115200 baud rate	It worked fine! ( but put PCB on the aluminum body of MacBook might “not” be a good idea )

	LED on-off switching test

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.