Currently been working on a shield based on a Max 7219/7221 chip to control an array of LED’s with the same logic used in the arduinome chip. My thinking is this could be a sort of EQ board or an expanded led array that attaches directly to the arduino. programmed for many uses but mainly because I wanted to make something that was similar to the materials of a arduinome board.
there is the schematic, the board itself is changing all the time as i try and get the traces right. The board itself is open source so you can develop on it. let me know if you want the brd or sch file and I will upload them. until then, I am going to try to make sure everything is right, then order the parts and pcb’s
so far an average cost for making this is about $0.50-$0.80 per LED (times 64) unless you can find cheaper costs. the LEDs are of the package size is 1206 and prices are quoted from digikey. Unless of course Seeed could pick up some blue smd 1206 LED’s heh. the capacitors are also 1206 package smd as well as the max 7219cwg which is the soic24 version. I am also using the Arduino-Various.lbr library from here for the arduino shield schematic. a total cost is around $40-45 depending on where you get your max chip. and thats of course before you buy the pcb since it takes so many LED’s.
I am not experienced in this so if you see issues, please let me know because I am going off of white papers and forums and googling.
What are you trying to achieve. You’re building quite a large array of LEDs, when you reach that sort of resolution wouldn’t it be better to use an existing array and build an interface or “shield”?
mainly i wanted to have a low profile shield with an led array on it, but also i wanted something that i could better my SMD soldering with
no real application in mind other than the same type of stuff you can do with the arduinomes minus buttons. just something to help me get better at soldering and eagle while looking cool at the same time.
It’s funny now that I’m pretty decent with SMD soldering, I prefer it over through hole, none of that mess of little wires to trim off and just much neater and most important smaller!
It’s definitely something I would learn, it’s not really that hard, and I only use a 40 soldering station, some flux (an absolute must!) and a little wick here and there.
There are so many out there and most have the same info, but do remember there is the photo resist method, and of course the laser printer method.
I’ve actually read about a way of “printing” them using an inkjet that prints to CDs and with special ink that acts as a resist. What was cool about this way is you could then print a soldermask and then a silkscreen. but you have to get a printer and modify it and get the ink also.
Well I don’t make PCBs to often at home. I usually breadboard then if it’s a simple one off, just protoboard it, or I’ll have PCBs made (like Seeedstudio’s propaganda service) since I’ve learned eagle. I’d like to get a small CNC router, or kit or build my own for making them at home though. When I do make the occasional one at home I just use the toner method since it’s the cheapest way.
A Dremel with a carbide bit (Can be had off ebay pretty cheap), even better is a dremel with the drill press attachment. I have to admit I’ve been thinking of getting a cheap CNC router, then you can make the board and drill all with precision, there not cheap but there are some on ebay for 499, sometimes TQFP packages are fidgety on toner method, but that’s in the future.
If you are looking for really down and dirty and the circuit is really simple you can go really cheap a sharpie! You can use a sharpie to act as a resist for etching, or also get one of those really cheap engraver pens and just use that to remove the copper, no etching at all, but that’s for really simple boards.
