[Gumstix-users] Serial Voltage Levels

[Paul H. <pau...@li...>]

Hi,

I am looking at building a custom piece of hardware to attach via the 
serial port to the gumstix. One of the key factors in this is the logic 
levels that are used with the gumstix serial port. Is the gumstix using 
0-3v, with standard CMOS logic levels (i.e. lower third is 0 and upper 
third is 1)?

Also, if we are using the above how does it interface correctly with a PC as

[QUOTE]
1. Serial Cables can be longer than Parallel cables. The serial port 
transmits a '1' as -3 to -25 volts and a '0' as +3 to +25 volts where as 
a parallel port transmits a '0' as 0v and a '1' as 5v. Therefore the 
serial port can have a maximum swing of 50V compared to the parallel 
port which has a maximum swing of 5 Volts. Therefore cable loss is not 
going to be as much of a problem for serial cables than they are for 
parallel.
[/QUOTE]

( from http://www.beyondlogic.org/serial/serial.htm )

Thanks,
Paul