Played with this one last night. Managed a 2"*2" format with single layer. Use surface mounted resistors for I2C pullups, resistor sip arrays for the keypad lines and sot23 format transistors. Just an unwinding depresurizing project to see what i could come up with.....
Not sure what size the holes are, but for prototypes that involve through-hole components I like to ample-size them. Makes rework easier. At least 0.035" or 0.040", especially for the connectors that have t0.025" square pins.
@Frank - Cool! I was going to try that after I get this board working. I went ahead and ordered a test run on what I have so far. I hope I didn't just waste $86 and change.
@Tracy - I didn't consider hole size. Hopefully they won't be too snug if I have to do any rework.
@Leon - I never did add that ground connection, but I'm sure there will be further revisions!
@ Mark, my design is one per chip always. When suggesting to another consider "you may want to xxx" as very strong recommendation. Since my stuff is one off, overkill is good and saves me time not spent chasing ghosts an intermittents.
Ah, unfortunately plain text doesn't convey intonation or _emphasis_ very well, so subtleties are lost -
I'd say "should" rather than "may" at least for that - to be clear.
I didn't want the OP to end up with a board that failed - remotely powered boards are
most in need of good decoupling after all.
I've enjoyed watching the progression of this project as I'm working on a PCB (for the first time) and all of this is completely new to me! Your project came out looking gorgeous! (I might ask folks in the forum for advice too )
Glad you like it Addie! I'm trying not to make any major adjustments to it until the first prototypes get here. But .... here's a version for the propeller platform. I just squeezed it onto the smaller footprint but I should probably map the output to prop pins. I did a a ground plane at least.
It's super snazzy! I'm just hoping my connections are right before I start trying to make the traces look good You should see my confusion when dealing with pins that are stuck between the vss/vdd pins. "But....it can't get out!...how do I get it out!......"
I realize I'm late to the game here and probably being a bit nit-picky, but...
It won't make any difference as far as the circuit functioning, but it looks like the PCF8574 chip and some of the other parts are not properly snapped to the 0.01" grid. This is causing a lot of traces to not line up neatly. Also, just to make things look nice, you should try to keep traces vertical, horizontal or on 45 degree angles when possible. The traces coming out of J1 and the area around R3/R1/R10 for example look a bit weird.
Any advice is appreciated Rick. I have the snap to settings at 0.025 so some pieces might not be on the 0.1 grid exactly. I've added a cooper pour on the top plane, eliminating the some of the traces. This allowed a shorter routing of the traced to J4. Thanks for the tips.
You should see my confusion when dealing with pins that are stuck between the vss/vdd pins. "But....it can't get out!...how do I get it out!......"
Although there are always exceptions, I find it's a very good general rule on 2-sided boards to run traces east-west on one side and north-south on the other. This allows you to use vias to get those signals out where they can run to where you want them. You can lay out a relatively simple board like doggiedoc's in a more ad hoc way, but add just a couple more connectors or IC's and it gets very hard to get all the traces where they need to go without some discipline.
Comments
@Tracy - I didn't consider hole size. Hopefully they won't be too snug if I have to do any rework.
@Leon - I never did add that ground connection, but I'm sure there will be further revisions!
I've attached the ExpressPCB files: These are offered as open source.
Thank you all.
Paul
Ah, unfortunately plain text doesn't convey intonation or _emphasis_ very well, so subtleties are lost -
I'd say "should" rather than "may" at least for that - to be clear.
I didn't want the OP to end up with a board that failed - remotely powered boards are
most in need of good decoupling after all.
Addie
It won't make any difference as far as the circuit functioning, but it looks like the PCF8574 chip and some of the other parts are not properly snapped to the 0.01" grid. This is causing a lot of traces to not line up neatly. Also, just to make things look nice, you should try to keep traces vertical, horizontal or on 45 degree angles when possible. The traces coming out of J1 and the area around R3/R1/R10 for example look a bit weird.
Paul
Although there are always exceptions, I find it's a very good general rule on 2-sided boards to run traces east-west on one side and north-south on the other. This allows you to use vias to get those signals out where they can run to where you want them. You can lay out a relatively simple board like doggiedoc's in a more ad hoc way, but add just a couple more connectors or IC's and it gets very hard to get all the traces where they need to go without some discipline.