Intel 8XC196NP, 80C196NU manual Serial I/O Port Signals and Registers, Serial Port Signals, Pin

8XC196NP, 80C196NU USER’S MANUAL

An independent, 15-bit baud-rate generator controls the baud rate of the serial port. Either the in- ternal peripheral clock or T1CLK can provide the clock signal. The baud-rate register (SP_BAUD) selects the clock source and the baud rate.

8.2SERIAL I/O PORT SIGNALS AND REGISTERS

Table 8-1 describes the SIO signals and Table 8-2 describes the control and status registers.

Table 8-1. Serial Port Signals

		Serial
Port	Serial Port	Port	Description
Pin	Signal	Signal
		Type
P2.0	TXD	O	Transmit Serial Data
			In modes 1, 2, and 3, TXD transmits serial port output data. In mode 0,
			it is the serial clock output.
P2.1	RXD	I/O	Receive Serial Data
			In modes 1, 2, and 3, RXD receives serial port input data. In mode 0, it
			functions as an input or an open-drain output for data.
P1.4	T1CLK	I	Timer 1 Clock
			External clock source for the baud-rate generator input.

Table 8-2. Serial Port Control and Status Registers

Mnemonic	Address	Description
INT_MASK	0013H	Interrupt Mask
		Setting the TI bit enables the transmit interrupt; clearing the bit
		disables (masks) the interrupt.
		Setting the RI bit enables the receive interrupt; clearing the bit
		disables (masks) the interrupt.
INT_PEND	0012H	Interrupt Pending
		When set, the TI bit indicates a pending transmit interrupt.
		When set, the RI bit indicates a pending receive interrupt.
P1_DIR	1FD2H	Port 1 Direction
		This register selects the direction of each port 1 pin. To use T1CLK
		as the input clock to the baud-rate generator, clear P1_DIR.4.
P1_MODE	1FD0H	Port 1 Mode
		This register selects either the general-purpose input/output function
		or the peripheral function for each pin of port 1. To use T1CLK as the
		clock source for the baud-rate generator, set P1_MODE.4 to
		configure T1CLK (P1.4) for the SIO port.

8-2