Power Pro mini 3.3v from usb ?

[Cliff Karlsson]

I want to use a Rpi+Arduino Pro mini 3.3v as a gateway and connect a RFM69HW as it needs 3.3v. Can I just cut a usb-cable and solder GND/VCC/TX/RX of the pro mini to the cables on the usb and use 10k+4,7k resistors as a voltage divider on the VCC? or do I need to put resistors on all four connections? And how do I connect the usb data + and data - ? Is data + supposed to connect to TX on the arduino?

[scalz]

hi.
it doesn't work like this..arduino pro mini has no hardware usb (I mean in the 328p chip). So you need an ftdi chip, or adapter for this.

but maybe there is another option. not sure if it could work as I have not tested yet. you should look at v-usb. it could be interesting in some case..

[Cliff Karlsson]

@scalz said:

no hardware usb (I mean in the 328p chip). So you need an ftdi chip, o

Ok, how would I use a mini pro as a serial gateway using a raspberry pi ?

[ToniA]

You need to connect it using a 3.3V USB to serial adapter.

Something like this: http://www.ebay.com/itm/3-3V-USB-to-TTL-Serial-Cable-FT232-Chipset-FTDI-USB-Cable-Adapter-Computer-Cable-/181870867906

[gloob]

Why not connect the arduino directly to the IO pins of the raspberry?
I have a similar setup running with a sensebender micro as a gateway.