Cheapest / lower parts count mCU with USB

Are you planning on making dozens or hundreds of these? If it is a one-off, I would have thought $4.50 would not be an unreasonable investment in a hobby. For a single piece, it's going to be hard to get significantly less when shipping and handling is included.

Do you need a USB host or device? What USB version?

I'am going to make 4-5 for myself, and may do a kit/kickstarter if people a re interested. Anyway, $4.50 is acceptable, but part of the fun of this pro ject is to try to make it for dead cheap.

, a spoon of synthetic plaster, a few centimeters of magnet wire and a micr o usb connector. Total cost is less than $2.

By adding an mcu I could :

-Ask for 250mA when the device is connected to a computer and not and usb w all adapter (this is mondatory, though nobody does it)

-Add an animation on the leds.

-Add an usb protocol to upload custom animations

Rising total price from $2 to $4.50 just for that is not really great. I co uld use a $1 mcu to make the animation, let it be programmed via UART and f orget about gently asking for 250mA.

Once again, $4.5 is not overpriced, but the fun is to do the whole thing on the cheap :)

Eliott.

It is an USB device. First need is to ask for the 250mA I will use, second need is to have an easy firmware or data upgrade of the device. Slow 1 endp oint hid or CDC would be enough.

For now, the 'best' solution is V-USB on an Atmega8A, but a crystal-less so lution would be nice since I will use air wiring.

Quick update :

Current winner seems to be PIC16F1459 : It just needs 2 capacitors, has 14k b of flash, 18 I/O pins and 1kb of ram. The cheaper PIC16F1454 is good too, but only has 14 I/O pins and no ADC (that may provide better capacitive to uch sensing than the digital version).

Cost for 10 SOIC pieces from microchip is about $25 including 3 day shippin g to europe (QFN or SSOP). $23.30 from Chinese sellers, 3 weeks shipping.

Hi,

also have a look at the C8051F383 (or C8051F38C): 32KB (or 16KB) FLASH,

Rene

A bigger problem than the USB interface might just be the high current drive I/O. Many MCUs provide a handful of high drive I/Os, but few provide 20 of them. They often restrict the total current drive if not the individual line drive capability.

If you are making 5 of these and others will be buying 1 or 2 each, you will do better focusing on ways to reduce the postage costs than the MCU costs.

What about *no* MCU, but a USB chip that gives you I/O ports instead and let the PC do the heavy thinking? Is it FTDI that makes a part with either UARTs, JTAG or GP I/O? I think it has a CPU inside and if you ask nicely enough they will let you program that.

AAAHAHAHAHAHAHAHAHA I thought 8051 was dead ;-)

You would think, eh? It's only 30+ years old. But it's still being used.

--Original 8748 User (precursor to the 8051)

Yep, I remember those. Every time you changed the code causing things to move, some of your branches broke because you couldn't branch across page boundaries. The UV erasable ones were something like $300 each when they first came out.

The 8048 sure made the 8051 look great...

Yup, just like the landline phone... except for the 100 million+ still in use.

I assume the USB host primarily serves as a power source. The gadget will operate on a USB loader also.

The C8051F38C someone mentioned is $1.45 @ 25+ from Mouser. Relative to the Microchip part, this has a faster core, and finer Baud rate resolution and 2 UARTS.