saa-xc886clm Infineon Technologies Corporation, saa-xc886clm Datasheet - Page 91

• Manufacturer Part Number: saa-xc886clm
• Description: 8-bit Single Chip Microcontroller
• Manufacturer: Infineon Technologies Corporation

The following formulas calculate the final baud rate without and with the fractional divider
respectively:
The maximum baud rate that can be generated is limited to
clock of 24 MHz, the maximum achievable baud rate is 0.75 MBaud.
Standard LIN protocol can support a maximum baud rate of 20 kHz, the baud rate
accuracy is not critical and the fractional divider can be disabled. Only the prescaler is
used for auto baud rate calculation. For LIN fast mode, which supports the baud rate of
20 kHz to 115.2 kHz, the higher baud rates require the use of the fractional divider for
greater accuracy.
Table 29
settings and deviation errors. The fractional divider is disabled and a module clock of
24 MHz is used.
Table 29
Baud rate
19.2 kBaud
9600 Baud
4800 Baud
2400 Baud
The fractional divider allows baud rates of higher accuracy (lower deviation error) to be
generated.
115.2 kHz, using different module clock frequencies. The fractional divider is enabled
(fractional divider mode) and the corresponding parameter settings are shown.
Data Sheet
lists the various commonly used baud rates with their corresponding parameter
Table 30
baud rate
Typical Baud rates for UART with Fractional Divider disabled
=
lists the resulting deviation errors from generating a baud rate of
----------------------------------------------------------------------------------- - where 2
16
×
Prescaling Factor
(2BRPRE)
1 (BRPRE=000
1 (BRPRE=000
2 (BRPRE=001
4 (BRPRE=010
baud rate
2
BRPRE
f
×
=
PCLK
(
BR_VALUE
------------------------------------------------------------------------------------
16
×
2
BRPRE
B
B
B
B
)
)
)
)
+
f
×
PCLK
1
(
84
)
BR_VALUE
Reload Value
(BR_VALUE + 1)
156 (9C
156 (9C
156 (9C
78 (4E
BRPRE
+
1
)
H
×
H
H
H
)
×
)
)
)
STEP
-------------- -
(
256
BR_VALUE
f
PCLK
Functional Description
/32. Hence, for a module
+
1
) 1
Deviation Error
0.17 %
0.17 %
0.17 %
0.17 %
SAA-XC886CLM
>
V1.0, 2009-09
(3.5)
(3.6)