I have played with Arduino boards... coupled with breadboards for extra devices... and more room/areas to tap the main power RAILS...etc..
I would like to start learning more about how to move towards more professional and permanent pcb type projects..
A question that came to mind.. and Im sorry if this is rather simple/noobish...
is about having your inputs NOT float?
like a switch for example?
To have it NOT float.. you need to have a resistor on the same INPUT line/pin as your switch.. and either connect to GND or V++ so the input isnt floating (no state)
When using the real Arduino board.. or coupled with a breadboard.. that sort of stuff is easy.. as you have tons of GND/V++ spots to tap all along the power rails..etc.
but take away your breadboard.. and you have limited places to use GND or V++.... especially if you have a custom board.. or something like the pro mini..etc.. where there is only I/O through holes..etc.... not really a 'dev' board like the UNO/Due..etc..
So how do you add all these resistors.. to GND for example, (V++) .. when you have a custom board or something like the pro-mini...etc
if your project has 5 switches.. thats 5 spots you need to find to GND to to stop floating..
this is NOT a specific project.. its just general question on how to approach these type of scenarios?
If you make your own PCBs, you have to run a ground (or positive) connection to each place that needs it. One of my projects has 12x 5V connections and 34x GND connections. It takes some time to figure out a route that makes everything work. The ground is usually the most challenging netlist to do. Plan your component placement accordingly.
Unless your PCB software includes the ability to autoroute traces, the best approach is the old school approach --
One layer goes vertically, the other layer goes horizontally, use vias as needed to connect. You can wind up with some pretty ugly boards, but so long as you do don't use traces that are wider than they need to be, you should be able to layout almost anything.
xl97:
Im not familiar with the 'old school' approach?
or what you mean by the vertical/horizontal layers??
How does the Femtoduino & pro-mini.. and others do this? (or dont they?)
Real boards are laid out with real software which can figure out how to route the traces.
Before people had computers at home (like, the 1970's ...) the easiest way to layout a board was have one side of the board have traces all going in one direction, while the other side of the board had all the traces going perpendicular to that.
On my boards (because I haven't bought software to do the layout for me, because I'm cheap ...) the top layer goes from left to right and the bottom layer goes from top to bottom. When I'm finished with the layout, then I figure out which layers are going from one side to the other for no good reason and change which side of the board the trace is on.