Quote Originally Posted by xnihilo View Post
What is the output of the pic? TTL or RS232?
RS232
What is exactly the inverted mode?
Just as the name implies. The signal is inverted. Up is down and down is up.

HSEROUT is always TRUE. So the MAX232 or equal is needed for this.

I agree with Steve, get an external OSC and save your headache for someplace else.