More cost effective than Pro Mini for product run?


I’m going to be doing a product run (an LED toy), and our prototypes have been using Pro Minis. At $18 per, it would be great to save some cash. We really only need 3 outputs (all with PWM), maybe 1 input. Can’t be any bigger than a Mini.

Any guesses on the cheapest solution? Is there a particular chip that would be better suited to our pin needs?

Or is it not really cost effective for a small company to do all that extra work (e.g. just stick with the Mini)?

I know my questions are a bit vague, but I’m interested in discussing any of the tradeoffs between arduino vs custom circuits for product runs.

Thanks for your suggestions!

if you only need 3 PWM + 1 input I think any of the atTiny chips would do. They are very cheap, but you'll need a custom PCB and code for them to work.

Thanks for the response. I've got an eye on those AtTinys.

The datasheet suggests that the AtTiny 4/5/9/10 have only two PWM channels each, so I'll need to check out the others.

Just found a post on the forum about AtTiny where WestFW says

The difference in cost between an ATmega chip ($2.50) and an ATtiny chip ($1.25) really isn't that much unless you're talking HUGE quantities, and in any case is likely to be dwarfed by the other costs in your device. The ATmegas are available in tiny MLF packages (smaller than a dip-8 by a significant amount), which should address physical size issues.

The core arduino environment is not very hard to port to other CPUs, but it might be more useful to point out that by the time you're capable of doing that, you'd probably also be capable of writing apps for the other CPU in "raw gcc" that didn't require any of the arduino environment.

A compelling argument. I'm gonna look around for existing PCBs like RBBB and report back with how cheap I can make this while still maintaining Arduino compatibility... It very well may be worth it to just use Pro Minis :) I wonder if I could do it without a PCB, and just glob the whole thing with hot glue to protect it and prevent shorts?

If anyone has any more ideas, please shout 'em out :)

Well, an ATmega8 remains arduino compatiblity and costs about $3. It may not be worthwhile searching too hard for an unfamiliar CPU...

How big is your production run?

Do you need a PCB to hold the rest of the circuit?

If the answers are less than 10 and no, then use an RBBB or equivalent.

If the answers are significantly more than 10 or yes, then roll your own PCB. I suspect that unless you get into huge volume, a mega8 or 168 is going to be the cheapest.

PCBs are cheap these days. You have to get over the hurdle of the toolchain, but once you do, it's dirt cheap.

Thanks for your advice!

In the short run, it seems hard to beat the cost of the Pro Mini (in terms of convenience). It may be that we need to take the design files to our PCB assembler and say "Make this, but cheaper, please." :)

Its harder to get much smaller or cheaper than a RBBB from $9.50 in Qnty 10, and you can leave off the powerjack (even regulator if you run batteries), and solder the chip in place.

You could also take his schematic, replace the dip with the 328 tqfn for a very small setup. Tho unless your quantity is >50 or something making your own pcb may actually cost more.