Firmware update of newer STM32s could be done over USB too - you don't need separate UART for this. Just wire BOOT pin (pins) to GPIO(s) from EOMA to allow entering firmware update mode (DFU over USB).

64pin seems an overkill - there a lot of other package options, e.g. 48pin QFN, not to mention the BGA variants. Also, F103 is quite old one, probably the price might be good, but I would recommend some of newer ones (Cortex-M0 even) - look at F0, F2, F3 series. A good option could be this: STM32F071CB, the price goes below $2.50 for 100pcs, and it seems to have all you need - http://www.st.com/web/catalog/mmc/FM141/SC1169/SS1574/LN7/PF259662

SiLabs "Precision 32" are also nice ones - very well balanced peripherals and packages (e.g. QFN40, SiM3U154), built in regulator from 5V (if needed). But the price is higher.

2014-08-07 12:07 GMT+03:00 Miguel Garcia <gacuest@gmail.com>:

2014-08-07 10:13 GMT+02:00 Luke Kenneth Casson Leighton <lkcl@lkcl.net>:

> blegh - and you need 2 of them _and_ 2 analog ICs as well. that's
> starting to make the STM32F103 (64-pin variant) look attractive. and
> i know you can get that at around the $2.50 mark in 10k volumes.
>
> *sigh* ok do you really need that USB Flash thing? because of a) the
> cost (at least $4.50) b) the number of ICs (4) it's starting to tip in
> favour of the STM32F again, i get the feeling you'd be better off
> wiring up the STM32F as a USB 1.1 device. you'll also need to wire up
> the UART to the EOMA68 interface and a couple of other pins to put it
> into "firmware upload" mode, but that's ok.
>
> the advantage there is that i have some GPL'd KiCAD designs with
> STM32F already in them (or have found some out there when i last
> checked).

Yes, the USB flash drive can be removed.

I think Daniel also prefers a microcontroller.

2014-08-06 14:18 GMT+02:00 Luke Kenneth Casson Leighton <lkcl@lkcl.net>:

> * one GPIO IC IN pin is needed for MicroSD "detect"

> * digital GPIO IC OUT pin needed for power-up of LCD
> * accelerometer IRQ goes to digital GPIO IC IN
> * digital GPIO IC IN pin connects to IRQ-OUT of AXP209
> * digital GPIO IC IN pin connects to Headphone-detect (in case you
> want to alter volume on headphone-out)

So, do we connect all this to STM32F? Or do we have to add the STM32F
and the digital GPIO IC?

Thanks.

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