Is the serial supposed to be inverted?

So I was trying to get an RS232 connection working between a Fez Cobra and a laptop today. It was not working. After monkeying around with it for a while, I found that the TX signal on the Fez was inverted. Is this normal behavior or is something wrong with my unit?

The signals on FEZ are TTL not RS232

TTL = 3.3V

RS232 = 10V and inverted


How are you connecting the FEZ ?

USB to serial adapter/cable ? RS232 Shield ? Custom circuit ?

Do’h, I pulled a homer. I was just connecting them directly :-[

It looks like I can get a converter for a few bucks.

U might damage fez Cobra’a serial port by direct connection. RS232 is higher than 10 volts! TTL with FEZ cobra can endure up to 5 volts.