[ntp:questions] Re: Meaning of PPS flag2 -- assert/clear

Uwe Klein uwe_klein_habertwedt at t-online.de
Sun Oct 15 18:14:23 UTC 2006


Hi,

RS232 signal sense is ( viewing pos voltage as H) :
	notRX
	notTX
	RTS
	CTS
	DCD
	DSR

because RS323 line sense is:
	L   +3v.. +23V
	H  -12V .. -3V

an unconnected RS232 Receiver Hardware pulls high (+3V++)
	signaling RX=L and thus (LINE)BREAK if
	this continues longer than one legal frame
	i.e a broken line

Receivers and Transmitters ( such like MAX232) are inverters
UART TTL IO signal sense is:
	RX
	TX
	notRTS
	notCTS
	notDCD
	notDSR
uwe




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