Intel 8XC196NP, 80C196NU, Microcontroller manual Spbaud

8XC196NP, 80C196NU USER’S MANUAL

SP_BAUD

SP_BAUD	Address:	1FBCH
	Reset State:	0000H

The serial port baud rate (SP_BAUD) register selects the serial port baud rate and clock source. The most-significant bit selects the clock source. The lower 15 bits represent BAUD_VALUE, an unsigned integer that determines the baud rate.

The maximum BAUD_VALUE is 32,767 (7FFFH). In asynchronous modes 1, 2, and 3, the minimum BAUD_VALUE is 0000H when using the internal clock source (f) and 0001H when using T1CLK. In synchronous mode 0, the minimum BAUD_VALUE is 0001H for transmissions and 0002H for receptions.

15

CLKSRC BV14 BV13 BV12

7

BV7 BV6 BV5 BV4

8

BV11	BV10	BV9	BV8
			0
BV3	BV2	BV1	BV0

Bit	Bit	Function
Number	Mnemonic
15	CLKSRC	Serial Port Clock Source
		This bit determines whether the serial port is clocked from an internal or
		an external source.
		0 = signal on the T1CLK pin (external source)
		1 = internal operating frequency (f)
14:0	BV14:0	Baud Rate
		These bits constitute the BAUD_VALUE.
		Use the following equations to determine the BAUD_VALUE for a given
		baud rate.
		Synchronous mode 0:†
		f	–	1	T1CLK
		BAUD_VALUE = -------------------------------------			or ----------------------------
		Baud Rate × 2			Baud Rate
		Asynchronous modes 1, 2, and 3:
		f		– 1	T1CLK
		BAUD_VALUE = ----------------------------------------			or -------------------------------------
		Baud Rate × 16			Baud Rate × 8
		† For mode 0 receptions, the BAUD_VALUE must be 0002H or greater.
		Otherwise, the resulting data in the receive shift register will be incorrect.

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