I've never designed a PCB before less than a week ago didn't even know what Eagle looked like so I'm happy to have any feedback you can offer. I read everything I could find on tolerances, best practices, etc but I'm a software guy and I'm sure I've overlooked something. I'm shipping these off for prototypes by Monday morning so if you see something that could prevent them from working I'd love to hear it!
This is essentially just the skinniest version of an FT232RL setup I could muster because of a special application requiring it to fit in a space 1/2" wide. It's 12mm x 30mm and uses a JST SH series 6 pin side-entry connector (SM06B-SRSS-TB). If anyone is interested in the eagle files I'm happy to provide them once I know they work correctly! Just let me know.
Any idea how hard these are going to be to assemble? I have a bit of concern that I made it too small for hand-soldering?
Wow, great catch, thanks. I just slid the trace above it (right under the "C" in "C1") to the right preventing it from pouring over there at all and now looks much better.
Craig, got your messages, one forwards to the other.
Nice work on the schematic & board design.
You have the output pins going out of RJ45 type jack? That an interesting idea. Then just make a cable adapter to mate to whatever you're using it with.
Did you do a ground plane for the bottom too?
I would make a little more clearance around the FTDI pins - those things are smaller than they look and are hard to hand solder; if you get shorts from pins to the ground plane underneath its very difficult to fix.
You could also place some rectangles along the edges of your USB connector mounting pads overlapping the ground plane so the backshell is grounded.
I updated the board (and image above) to include all of your excellent suggestions. I had to hit google to learn about tRestrict (41) for Crossroads' suggestion but very glad I did. I can almost guarantee I would have hit that ground plane under the IC as I'm not the world soldering champion.
I'm starting to get excited that my first board (although very simple) might actually work...
CrossRoads:
You have the output pins going out of RJ45 type jack? That an interesting idea. Then just make a cable adapter to mate to whatever you're using it with.
It's much smaller than RJ-45. I'm also making some breakout PCBs from that connector to 0.1" pins for easy testing/debugging at the same time.
CrossRoads:
You could also place some rectangles along the edges of your USB connector mounting pads overlapping the ground plane so the backshell is grounded.
This seemed like the right approach to me too strictly out of intuition but the datasheet doesn't show the shield grounded and I read somewhere about some sort of caveat to consider when doing that that I didn't understand. Other designs I've seen don't seem to so I just left it off. I haven't been able to find the info I'm talking about, can you fill me in why it would be a good/bad idea to ground the connector shield?
frank26080115:
hey guys, with a RJ-45 jack and ethernet cable, how long can the cable be?
the traces where C1 and C2 meet has a sharp corner, I read that acid can get trapped in such corners during the PCB manufacturing process
According to my quick research you can find all of the information regarding maximum cable length here: RS232 Specifications and standard - Lammert Bies. It varies by baud rate with a maximum cable capacitance of 2500pF. You'd have to do some research/testing I suppose but that should get you started. I don't have any personal experience and I'm only using this connector to carry a few inches.
@wayneft: Nope, it's never too late to learn! (It was too late for sending it off for a first prototype run though.) I went and looked and you're absolutely right. It took me a minute to figure out how you were even able to tell that from the picture - once I figured it out it was obvious, made perfect sense, and I'm glad you pointed it out!
My first board I sent to the maker and he rang back and asked if it was a joke ? I said no ,he said then is your first board and I said yes and he said well better have another go!
tytower:
My first board I sent to the maker and he rang back and asked if it was a joke ? I said no ,he said then is your first board and I said yes and he said well better have another go!
wow seriously? would you be willing to post a picture of it?
Heh... that's funny. I'd love to see a pic too as a frame of reference if you have it laying around.
I'm still anxiously awaiting delivery. I used dorkbotpdx since I've had a few of their boards others made and they seem very high quality. I'm expecting I might receive them early next week and I'll be sure and give another update.
