PDA

View Full Version : getting started



Celtic
11-12-2010, 01:43 PM
I want to built my own starterkit but cannot find
a schematic for the USB connector/interface.
Does the propeller 3.3v I/O match with 5V TTL?

please help,

thanks,

jmspaggi
11-12-2010, 01:45 PM
Take a look here (On page 2):

http://www.parallax.com/Portals/0/Downloads/docs/prod/schem/PPDB_A_Schematic.pdf

I might give you the answer.

JM

andrewsi
11-13-2010, 12:04 AM
There's different versions of the FTDI chip, some have a 5v interface on the serial side and others (including the one used on the Prop demo board) are a 3.3v interface. If you have a choice, just get the right 3.3v USB chip.

There are other threads that suggest that if what you have is a 5v-only device, it's reasonably safe to connect those to Propeller pins as long as you put a 1K resistor or so in series between the device and the propeller on each line you connect. It drops the voltage and limits the current enough to keep from blowing anything up.