ATTiny85 Arduino part 2, One Potato, Two Potato, Three Potato, more

I put the ATTiny85 Arduino project aside for a few weeks and when I picked up my circuit board again I used another laptop, my trusty Samsung Netbook actually. I followed procedure carefully and sure enough it worked first time and every time! I made a few minor adjustments to the PCB pattern and printed off some copies for my grade 12 Computer Studies class. We etched the boards using the Toner Transfer method and got some good looking PCBs. A few days later the components were soldered onto the boards and the Boot Loader burned into a bunch of ATTiny85 chips. Next thing you know: one potato, two potato, three potato more -

Congratulations to the grade 12 class that built these. Excellent work.

Here are the instructions I gave to the class:

INSTRUCTIONS

STEP 1

Manufacture the circuit board using the trace layout given following the classroom procedure. You may want to add 1/8 inch holes in each corner so that your board can be mounted using 4/40 screws at a later date.

STEP 2

Familiarize yourself with the schematic diagram and parts placement.

Identify the following parts:

• USB signal
• Power
• Reset
• i/o

STEP 3

Place the components and solder them in place in the following order. Clip the excess leads after each set of components is soldered.

• Capacitors
• 8 pin socket
• 1.5kΩ resistors
• 1N4148
• 22Ω resistors
• 3.6V zener diodes
• LEDs
• reset pushbutton
• 9 pin header
• USB socket

STEP 4

Use a multimeter to check for shorts between traces. Notice that the USB power and signal traces are very close together and a USB short could affect your computer. If there are no shorts connect your Atiny85 Arduino via USB to a laptop for a moment. The green power LED should glow (and hopefully nothing else will happen).

STEP 5

Unzip the Digispark Arduino IDE and locate the directory in the installs directory on a school laptop.

STEP 6

Use the InstallDriver utility inside /DigisparkArduino-Win32/DigisparkWindowsDriver to install the driver.

STEP 7

Run the Arduino IDE inside of /DigisparkArduino-Win32/Digispark-Arduino-1.0.4/

• Do not connect your Atiny85 Arduino to the computer yet.
• Under Tools choose Board and choose Digispark (Tiny Core).
• Under Tools choose Programmer and choose Digispark.
• Under File choose Examples and choose Digispark_Examples and choose Start.
• Click the upload button and watch the message area at the bottom of the IDE.
• Plug in your Atiny85 Arduino when the “Plug in device now . . .” message appears. Pin1 (sometimes called PB1) is pin 6 on the chip. Your built in red LED is connected to this pin. The program should cycle the LED on and off at 1 Hz.

Handy Reference Chart

pin	Pin	Analog
1	Reset
2	3	Input 3
3	4	Input 2
4	Gnd
5	0	PWM,AREF,MOSI
6	1	PWM, MISO
7	2	Input 1, SCK
8	VCC

Here is a pdf file containing a sheet of  16 pcb layouts.