7. Electronics design¶

Assignments for the week¶

Group assignments¶

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

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 credit: Simulate its operation. Render it.

Requirements¶

Shown your process using words/images/screenshots.
Explained problems and how you fixed them, including how you worked with design rules for milling (DRC in EagleCad and KiCad).
Outlined problems and how you fixed them.
Included original design files (Eagle, KiCad, Inkscape, .cad - whatever).

Group assignments¶

See 2019 Fablab Taipei Group site Week 7

Individual assignment¶

BOM¶

Parts	Spec.	Quantity
ATtiny 44A		1
Resistor	0 ohm	1
	100 ohm	2
	10k ohm	2
Crystal	20 MHz	1
Capacitor	0.1 nF	2
	100nF	1
LED	Red	1
	Yellow	1
Bottom		1
Heder	2x3	1
	1x6	1

Redraw and check the design rules.¶

Download and install Eagle. Download free version
If needed, change the language by command line or .bat file, and use it as a shortcut. cd <path of eagle> SET LANG=en_US start eagle.exe
Download and unzip Fab academy libraries. Download libraries here
Open Eagle, load library at file / open / Library.
Save it then close it.
Create a new project then a new schematic.
Check Datasheet to replace by crystal. It shows reccommended capacitor as well.
Add parts, duble click to palce it, Esc to finish.
Link parts.
Draw a open end then name it to link with those have the same name.
Right click to set values of parts.
Swich to board view
Set up Design rules frist. Otherwise you will need to draw all path again.
Move and rotate to arrange parts.
Route parts. Don’t use auto route, It only works when you need a hint.
Check Errors

Make it¶

Show only top layer and export image.
Use document layer, same to set and export the outline.
Go to your images and set (or check) the right size by image editer.
If you have a wrong size…
Mill it, soldering it, same as week 5 (or open in a new tab)

Test it¶

After downgrade Arduino IDE to 1.6.9.0, I can programing attiny 45 borad. But when I programming attiny 44a, the IDE returns an error.

avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x15
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x15
avrdude: stk500_getparm(): (a) protocol error, expect=0x14, resp=0x14
avrdude: stk500_getparm(): (a) protocol error, expect=0x14, resp=0x01
avrdude: stk500_initialize(): (a) protocol error, expect=0x14, resp=0x10
avrdude: initialization failed, rc=-1
Double check connections and try again, or use -F to overridethis check.

Try it again

avrdude: Expected signature for ATtiny44 is 1E 92 07
Double check chip, or use -F to override this check.

After change two capacitor that with cystal to 10 pF, and remove external clock, I guess it’s a soldering issue.

I will make another board to test.

A new board works fine.

Code¶

Following is the code for Arduino IDE.

int blink_time = 500;

void setup() {
  // initialize digital pin 13 as an output.
  pinMode(2, INPUT);
  pinMode(3, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  if (digitalRead(2)==HIGH){
    blink_time=1000;
  }
  else if ((digitalRead(2)==LOW)){
    blink_time=300;
  }
  else {
    blink_time=500;
  }

  digitalWrite(3, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(blink_time);              // wait for a second
  digitalWrite(3, LOW);    // turn the LED off by making the voltage LOW
  delay(blink_time);              // wait for a second
}

Files¶