So, this is something else I like to do: tinker with PCB layout and taking projects (some blatantly ripped off from elsewhere, some not) and creating a board that I might like to have manufactured.
Almost always I’m doing this as a mental exercise, but often the results are handy to have, and so I figure they’re worth putting up here.
What does it do?
Well, first off, it’s an Arduino shield. If you don’t know Arduino and all that jazz, go look it up; the rabbit hole goes pretty deep. This shield works in tandem with the ever useful Arduino ISP sketch that comes with the Arduino IDE, and it is for programming Atmel AVR microcontrollers. Without going completely red pill on you, let’s keep it simple by saying it lets you program other chips like the one that powers the Arduino, and let’s you do it either by dropping the chip into a special socket on the shield itself, or by using a 6-pin or 10-pin cable specially designed to connect to other pre-made boards that might have the chip soldered on or in a form factor that is not easy to otherwise program. See, re-reading that last sentence still hurts my eyes, and I know what the damn thing is supposed to do!
Do I want it?
If you don’t already have a USB-based AVR programmer handy, this one will quickly let you plug it onto an existing Arduino (or compatible pin layout), upload the Arduino ISP sketch, and then start flashing chips. If that sounds handy to you, then yes, you want it.
Can I tweak it?
How expensive is it to make this?
Now you’re talking brass tacks. Since this is full sized in terms of Arduino shields, it surpasses many of the PCB “deal” sites that give you a pretty decent price for a limited 25 square centimeter (5cm x 5cm) layout. I’ve tried several and I will probably get around to posting my opinions of each on this blog once I get my gumption up. This shield is 2.1 x 2.7 inches (53.3mm x 69.2mm approximately), and I know sites like Batch PCB will sell exactly one to you (note that it’s an earlier version) for $14.52 plus $10 “handling” just to set up the job. Just one example, but gives you an idea of what you’re in for from the PCB perspective.
From a parts perspective, the most expensive piece by far is the zero-insertion-force (ZIF) socket, which will run you north of $10 easily. I tend to favor Mouser Electronics right now, but I’m finding they don’t stock every little thing I need, so here’s my game plan for parts sourcing (and clearly this list favors North America, duh):
- Mouser, if they stock it
- Newark, if Mouser doesn’t have it
- Digikey, if Mouser and Newark come up empty
- Sparkfun, SeeedStudio, Adafruit, and the other maker-friendly sites
- AliExpress if I have to order direct from China
- If I can’t source it from any of them, I should find another damn part, don’t you think?
The bill of materials, maestro:
|C1||10µF||Ceramic Cap, 10% X7R||TDK||FK26X7R1E106K|
|C2||0.1µF||Ceramic Cap, 20% Z5U||Kemet||C320C104M5U5TA|
|J1||ICSP 6||2 row, 6 pin header||FCI||67996-206HLF|
|J2||ICSP 10||2 row, 10 pin header||FCI||67996-210HLF|
|J3||ATMEGAxx8 ZIF SOCKET||Narrow gauge ZIF socket||Aries||28-3554-10|
|Wide gauge ZIF socket||3M||228-1277-00-0602J|
|LED1||RUNNING||Green LED, 5MM||Cree||C503B-GCS-CY0C0792|
|LED2||ERROR||Red LED, 5MM||Cree||C503B-RCS-CW0Z0AA2|
|LED3||PROGRAM||Blue LED, 5MM||Cree||C503B-BCS-CV0Z0462|
|R1||100Ω||1/4W, 1% Metal Film||KOA Speer||MF1/4DCT52R1000F|
|R2||100Ω||1/4W, 1% Metal Film||KOA Speer||MF1/4DCT52R1000F|
|R3||68Ω||1/4W, 1% Metal Film||KOA Speer||MF1/4DCT52R68R0F|
|R4||120Ω||1/4W, 1% Metal Film||KOA Speer||MF1/4DCT52R1200F|
So where do I get the design?
The files are up on the Github (and which are Eagle CAD 6 format, if you are wondering), at the following excellent location:
Any updates will likely be made to this post, assuming that I don’t move it to a static page (which may eventually happen, so it doesn’t get buried forever). Since the software is already written, I don’t expect to publish much more about this part. But you never know.