Intel 8XC196NT User Manual page 549

8XC196NT USER'S MANUAL
SP_BAUD
SP_BAUD
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 XTAL1 and 0001H when using T1CLK. In synchronous mode 0,
the minimum BAUD_VALUE is 0001H for transmissions and 0002H for receptions.
15
CLKSRC BV14
7
BV7 BV6
Bit Bit
Number Mnemonic
15 CLKSRC
14:0 BV14:0
C-54
BV13 BV12
BV5 BV4
Serial Port Clock Source
This bit determines whether the serial port is clocked from an internal or
an external source.
1 = XTAL1 (internal source)
0 = T1CLK (external source)
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
BAUD_VALUE =
Baud Rate
Asynchronous modes 1, 2, and 3:
---------------------------------------- - 1
BAUD_VALUE =
Baud Rate
†
For mode 0 receptions, the BAUD_VALUE must be 0002H or greater.
Otherwise, the resulting data in the receive shift register will be incorrect.
Reset State:
BV11 BV10
BV3 BV2
Function
OSC
--------------------------- -
– or
×
Baud Rate
2
F
O SC
------------------------------------- -
– or
×
Baud Rate
16
Address: 1FBCH
0000H
8
BV9 BV8
0
BV1 BV0
T1CLK
T1CLK
×
8