My projects and ramblings

Welcome to My Scratchpad
Thursday, March 30 2017 @ 11:31 PM BST


This is my take on the Arduino platform.

It plugs directly on to the side of the breadboard bringing all the data and analog pins directly on to the board with the 5v and ground rails.
Its my first home made double sided board and in fact only my second home made pcb using the toner transfer method. There are a few bits I can improve on the pcb layout such as movong more of the traces to the top side of the pcb. It took two attempts to get the top and bottom mask aligned but finaly I got them almost spot on.


Heres the board in all its glory. Top and bottom.
Selectable power, by jumpers, either from usb or external power supply.
Power on led.
Jumper to enable the auto reset.
Space to plug in a sparkfun ftdi basic usb board.
It has one of my old 168 ic's in it for testing running of course the blink sketch.
I also used the toner transfer method after etching the board to print the lettering on the top of the board to show the analog/digital pin numbering.

Im quite pleased with how this turned out. I learnt a lot about home pcb productions especialy the limitations with the transfer method and resolution of the laser printer. I had to take very careful notice of clearances between pads and traces. They may have looked good on screen but when you print them they can run together. I had to resize all of the pads for the ic socket and pin headers. The lettering on the top of the board in toner turned out very well. Maybe this could be done on a colour laser with colour toner. I only have a mono laser printer.

This is the reason I did it, as well as to practice making my own pcb's.
On the left of the image below is how Ive been working till now with the Arduino loose either on top or beside the breadboard with long leads tying in to the breadboard. But on the right you can see my new board plugged directly into the breadboard with all the digital, analog, 5v and gnd easily to hand. All nice and secure.

And after

Heres the schematic

I used the toner transfer method to produce the masks for the pcb's. There are a lot of tutorials out there found if you google.
I found this one particularly useful: It does talk about lining up double sided boards.
Alternatively you could do this single sided and solder wires to to the vias instead of using the top mask.

PDF's of the top, bottom and lettering masks can be found here:

All the parts are very common to Arduino

C1 22pf capacitor

C2 22pf capacitor

C6 47ufd capacitor

C7 47ufd capacitor

C3 0.1ufd capacitor

C4 0.1ufd capacitor

C5 0.1ufd capacitor

C8 0.1ufd capacitor

R1 10k resistor

R2 560 Ohm resistor

D1 1N4004 diode

IC1 ATMEGA168-PU Arduino-AVR or 328 & 28pin IC socket

IC2 7805T voltage regulator

JP1 Jumper 2 pin

JP2 Jumper 3 pin

X1,X3,X4 pin headers

X2 right angled pin headers 6 way

LED1 3MM LED red

Q1 CRYSTAL 16.000MHz


S1 switch-omron 1

I made a few little mistakes on my board in the pictures.
Missed a via on one of the pins for the reset jumper. So I soldered to the wrong side of the board and it took me a while to find out why the auto reset wasnt working.
I have fixed this on the board and its corrected in the masks linked to above.
I managed to solder bridge a few of the pin headers. As they are so small I couldnt see the bridge without a magnifying glass.
I found them with my multimeter using the continuity tester after the board wouldnt upload the sketch, but kept loosing the usb port in the ide.

I would also share more of the traces on both sides of the board as Im sure I could have made it smaller.
and I found the traces from the Atmega IC to the pin headers a bit tight. It took me a few attempts to route them all with enough space for my printer.

This was all done in Eagle the free to use version.
I dont think Im allowed to publish the eagle files.

A link to my post on the Arduino forum:

Feel free to use my ideas if they are usefull to you.


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