Intel 8XC196MC User Manual page 527

8XC196MC, MD, MH USER'S MANUAL
SPx_BAUD
SP x _BAUD
x = 0–1 (8XC196MH)
The serial port baud rate x (SP x _BAUD) register selects the serial port x 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 BCLK x . In synchronous mode 0,
the minimum BAUD_VALUE is 0001H for transmissions and 0002H for receptions. In synchronous
mode 4, the minimum BAUD_VALUE is 0001H for both transmissions and receptions.
15
8XC196MH CLKSRC
7
BV7
Bit Bit
Number Mnemonic
15 CLKSRC
14:0 BV14:0
C-50
BV14 BV13 BV12
BV6 BV5 BV4
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 = input frequency on the XTAL1 pin (internal source)
These bits constitute the BAUD_VALUE.
Use the following equations to determine the BAUD_VALUE for a given
baud rate.
†
Synchronous mode 0:
F
XTAL1
------------------------------------- - 1
BAUD_VALUE =
Baud Rate
Asynchronous modes 1, 2, and 3:
F
XTAL1
---------------------------------------- - 1
BAUD_VALUE
=
Baud Rate
Synchronous mode 4 (SCLK x # output):
F
XTAL1
------------------------------------- - 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.
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Address:
Reset State:
BV11 BV10
BV3 BV2
Function
BCLK x
--------------------------- -
– or
×
Baud Rate
2
BCLK x
------------------------------------- -
or
–
×
16 Baud Rate
–
×
4
1F84H, 1F8CH
0000H
8
BV9 BV8
0
BV1 BV0
×
8