Learning from my mistakes...
Thought I would keep this thread alive, and share my "learning experiences" in hope that others might benefit from the mistakes that I made.
My PCB's just arrived. These are a first for me, and here are some scans.
(I've flipped the bottom layer left-to-right, so that you can look at them
one above the other, and things will line up)
The third scan has certain areas highlighted, and here are the lessons learned from each of those. (I will continue to post any further snafu's as I encounter them)
1. GREEN - I went to "dry fit" the component only to find that the legs of the part were not in alignment with holes in the board. After some head scratching I went back to the Eagle library, and the picture in the library matches the datasheet... but
DIDN'T match my board
. I went to add (temporarily) another one of these to my design, and was shocked to see "you have one of these in you design, but the library has been updated, would you like to use the new part?"
(ARgghghgh... the original library was wrong - LESSON: Always check packages for all parts in the library (NEVER ASSUME))
[Solution: I can install the part on the solder side, and all the pins will line up correctly.]
2. RED - This is for a 2x2 LED array. Turns out the package I have is slightly wider than the pin spacing here. So the two rows of 4 are actually angling in ever so slightly. The package, therefore, can't sit 100% flush with the board.
I'm sure the solder on 8 pins will hold the part, but it would have been nice to have the part smooth up against the board. LESSON: Always check packages for all parts in the library (NEVER ASSUME))
[Note: Due to the pinout of the part, I can actually install this from the solder side as well, and have the LED's run beside the IR receiver (see Note 1 as to why)]
3. PINK - Silkscreen atop of conduits - I should have noted this and moved those Rx labels
4. YELLOW - This is a "what was I thinking" moment. I have a trace leaving a through hole pin, travelling about 1mm, and then going through a conduit to the other side of the board. (Spotted this as I was re-working the design for a TSOP part. Can't believe I did that)
5. TEAL - This is actually a design issue, and not with the R4 that is highlighted. R4 is a pull-up on the SDL line of the I2C bus. As I was perusing the datasheets for the temperature sensor, I found that I should have pull-ups on the SDA, and the ALERT lines back from the part. Luckily I have the I2C breaking out to a header, and so adding a pullup (for the SDA at least) will be trivial.
Lesson: RTFM - read the *FULL* manual
6. BLUE - This is meant to be a "power" connector as found on 3.5" drives etc. I had thought to canabalize some old drives to get the connector. When I went to do this, I found that they all were 90-degree connectors, and thus wouldn't fit on my board. So my plans to use "old stuff off my workbench" fell flat. I'm going to have to purchase a couple of connectors... NEW
eek
.
LESSON: Make sure you have the parts, before putting them in your design.
Solution - either buy new parts, or consider running that "90-degree" connector off the bottom side of the board (I see a trend here). What the heck I can put the switches (RESET/PROG) on the bottom as well. Not quite the original intent, but should still function quite well as the "first" proto-type.
I will keep you posted as I work my way through.