Intel 8XC196NP, 80C196NU, Microcontroller manual Spbaud

Models: Microcontroller 80C196NU 8XC196NP

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SERIAL I/O (SIO) PORT

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.

 

 

 

 

 

 

Figure 8-7. Serial Port Baud Rate (SP_BAUD) Register

8-11

Page 178
Image 178
Intel 8XC196NP, 80C196NU, Microcontroller manual Spbaud