I received the boards back from Seeed Studios two weeks and four days after placing my order. I’m shocked by the quick turn-around, especially since I selected the slowest shipping option available which itself could have taken three weeks.
I’ve been pretty busy with work lately but finally found a bit of time to populate a board and get some test code running. I’m happy to report that I made no design errors. Everything seems to work as planned! Well, that is after I discovered the tiny trace bridge between two vias which prevented ISP communications with the chip. A sharp razor blade fixed that right up. I understand that this type of manufacturing error is not uncommon and it doesn’t really bother me.
Above is a fast-motion video I made while populating the second board. I’ll be sending this one to my friend Christian who is going to lend a hand adding features to the firmware. Hand soldering the mostly SMD project wasn’t too hard, but it did take about an hour. If I were making any more than two of these it would be worth it to order a stencil and procure solder paste and an old toaster oven for reflow. Perhaps on the next project.
In my next post I’ll talk about adding the LEDs. This took a long time. The first spire took about 45 minutes, by the twelfth spire I had it down to around twenty. Here’s a peek at the final product:
A lot of work went into designing this board. Thanks to help from Chris Meyer and Devlin Thyne I ended up with what I think is a design that will be friendly for the PCB manufacturer.
The parts order from Mouser came in on Saturday. I printed out the copper layers and checked all of the footprints against the parts. Everything looks just perfect. Yesterday I placed an order with Seeed Studio for ten copies of the board. Hopefully I’ll have then in hand in about two or three weeks.
Click on the image above for a larger version of the artwork. Or you can checkout the Kicad files from my git repository. This board is tagged as brd-v1.0.
I’ve been working with some 7 segment displays lately. I found an old computer on the side of the road and pulled a 3-digit display out of it. The hundreds digit can only display a 1 and it has no decimal points. After pulling it off of the board I find that it is a 16-pin module; one pin is common anode, one pin is the cathode for both segments of the hundreds digit, and the other 14 pins are cathode pins for one segment each.
I did some breadboarding with this module and was able to get things working pretty easily. When I decided to do some PCB design things became more complicated. For ease of programming I had connected all of the segments of the ones digit to PortD of an ATtiny2313. I then connected all of the segments of the tens digit as well as the single pin for hundreds to PortB. This setup makes for easy coding as each number you want to display can be stored as an 8-bit char and written directly the the Port for the corresponding digit. The problem is that the board design to match this is not at all easy. Continue reading →