This is Jawher Moussa's blog

in which he writes about technical stuff

I created my first PCB !


Earlier this morning, I received 10 of these beauties in my mailbox:



(Overly pessimistic) Bottom:


This is a development board I designed to ease prototyping with Atmel’s tiny 85 micro-controllers. It’s a rather basic design with the tiny 85 in a DIP8 package in the center with traces to expose 5 of its digital pins (PB0 to PB4) plus ground and VCC via a header to the top.
To the bottom, other traces connect to a 10-pin ISP connector for programming.
There is also a power indicator led, a reset button and decoupling caps, and that’s about it.

Here’s an assembled board connected to the programmer and plugged in a breadboard:


I’ve created this board using Eagle CAD. Here’s the schematic:


The board layout:


And the part list:

Part Value Device Package
C1 0.1uF Ceramic disc capacitor 0805
C2 100uF Electrolytic capacitor CPOL-RADIAL-100UF-25V
PWR LED 0805
PWR_R 1K Resistor 0805
RESET Tactile switch TACTILE-PTH
RST_R 10K Resistor 0805

This PCB design was fabbed using Seeed Studio’s fusion service: an incredibly cheap offer where you get 10 5cmx5cm PCBs for only 9.99$.

I soldered components on 2 of them, and after a bit of stumbling and yak shaving, mainly due to a buggy USBasp programmer, I got the boards to work beautifully.

It was also my first time soldering SMD devices (0805 resistors, capacitors and leds).
I was shocked the first time I hold a 0805 resistor in one hand with the iron in the other. It was tiny. Really tiny. I was like no way I’m going to be able to solder this. But it wasn’t that bad. The only part I struggled with was the power indicator led, and it turned out I was trying to solder the wrong package (a 1206) which was bigger than the pads.

/me very proud !

Humble beginnings:


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