this videos is on the circuit board design aspect if you're more interested in the
PCB manufacturing aspect you can click here now
or watch this video and click the link at the end. I figured I'd make a video
about how I do my projects
instead of showing you what I've done I'll show you the process I normally go
through to make it
so I saw this LCD on e-bay the reason behind
why I purchased it will become evident and later video and I wanted to
interface with it
so I bought the LCD without looking twice datasheet
actuating I didn't even look once and it has this ribbon cable connector on the end here
and they gave me this little ribbon cable connector
to PCB thing so let's see if I wanted to make this display something
from USB on the computer like the computer controls what's on the LCD
how would I do it
so
for this part I'm using KiCad and sped it up a
believe it's round a twenty times first part is that lay down the processor for an
using
an ATMega32u and
and I go look at the data sheet to see what the references for the power
because the part is 3.3 volts only I need to configure the AVR to be
a 3.3 volt AVR as you can see it also needs an external crystal
and all the basic parts like a program header I'm adding the USB stuff
which i'm taking from another reference document I've made for myself
all these things just go together kinda
based on other designs the I've done past that's why it's so quick
if you have to start from scratch, it's not that bad
but you get faster as you go here i'm looking up the data sheet for the
LCD trying to figure out exactly which pins go where and how to hook it up
and I'm just copying their existing reference design again
very little this is my own work and that's generally the way that most
engineering goes is that you just try to figure out well I'm gonna do
other people do because it works how would I go do that
As you can see, I'm just wiring it up in the same way that their reference diagram
has set up for me I'm just kind of going back and doing some housekeeping
and making sure I select all the footprints correctly for all the parts
additionally because
this uses an FPC that I've never used before I have to lay out a new design
so this new design is done in the KiCad editor
and it's pretty simple, you just pull open the editor and you start
you need a calculator to figure out how to place parts
place or pads once you do you get a pretty good idea as to where everything
goes
and the new layout that the pads and now this is a footprint for the new FPC part
actually messed up and got the pins backward as you can see it takes a little bit longer
than
you tell but overall it works out
so now I'm putting all the parts down kinda been a rough idea on out on the page
because I'm doing this on one layer I have to be kind of careful of
the orientation and said above all the parts
I can't have vias so gonna be really careful about how these things line up
additionally because this part has such fine pitch
I really have to use different tolerances and set things
up in different ways I normally do. now I'm going to have to move it over to
topor
order to do this you export from KiCad and you open it up in topor
this helps you lay out the board unfortunately the first time through
basically
always will demand that you have some vias so you have to play with parts
try to get it to work without any vias and that's just kind of an iterative
process just keep going over and over and over it
sometimes you have to play around with the pins, which pins hook up where sometimes you even
have to
abuse above the pins makes on the pins route through the wrong places
in order to get this to work but in general
most designs I do I can figure out a way to get it down to a single layer
I used to do this all manually but topor is about as good as I am so I figure why
waste the effort
as you can see just tweaking it trying to get parts closer together
and trying to play with the settings to get the layout that I want is a pretty
time consuming process
trying to pull it back in I as you can see here I decided I wanted
a new part I want will put a different header on in case I want to interface to
other things this is
and I2C header I use and then I just
as the schematic added to the layout try to fit it in a way that
will still fit on one layer and then I go give it to topor again
and again and again and again cycling through topor
trying to play with that give myself as best tolerance as possible
and trying to keep it all on one layer
so a lot of just competing things gotta play with a lot to
really get it quite right it took me probably a month or two to learn how to
topor effectively
but overall I'm very happy with it
and here you can see I'm just adding in some artworks, some text
some guide so I know which pins are one and what not to make the process easier
and yeah this is just about there adding in the ground plane and we're good to go
now I'm going to export it as a PostScript file, so that I can import it
some purists out there I'll say all you need to leave it as vector but now I
just use 600 DPI
thats plenty good I'll import with anti-aliasing because the laser printer
supports that
and I invert the colors and flip it left to right
and that's because you want the artwork side to be as close the copper is
possible
thanks for watching how I designed my circuit boards now you wanna see how
they're actually made
you can go click the link right here to follow on to the next video