XC886/888CLM
Serial Interfaces
User’s Manual
12-13
V1.3, 2010-02
Serial Interfaces, V 1.0
The following formulas calculate the final baud rate without (see
) and
with the fractional divider (see
(12.2)
(12.3)
The maximum baud rate that can be generated is limited to
f
PCLK
/32. Hence, for a module
clock of 24 MHz, the maximum achievable baud rate is 0.75 MBaud.
Standard LIN protocol can support a maximum baud rate of 20kHz, 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
20kHz to 115.2kHz, the higher baud rates require the use of the fractional divider for
greater accuracy.
lists the various commonly used baud rates with their corresponding
parameter settings and deviation errors. The fractional divider is disabled and a module
clock of 24 MHz is used.
The fractional divider allows baud rates of higher accuracy (lower deviation error) to be
generated.
lists the resulting deviation errors from generating a baud rate of
115.2 kHz, using different module clock frequencies. The fractional divider is enabled
(fractional divider mode) and the corresponding parameter settings are shown.
Table 12-2
Typical Baud rates for UART with Fractional Divider disabled
Baud rate
Prescaling Factor
(2
BRPRE
)
Reload Value
(BR 1)
Deviation Error
19.2 kBaud
1 (BRPRE=000
B
)
78 (4E
H
)
0.17 %
9600 Baud
1 (BRPRE=000
B
)
156 (9C
H
)
0.17 %
4800 Baud
2 (BRPRE=001
B
)
156 (9C
H
)
0.17 %
2400 Baud
4 (BRPRE=010
B
)
156 (9C
H
)
0.17 %
1)
(BR_VALUE
x
BRPRE
2
x
16
PCLK
f
rate
baud
+
=
1
)
1
_
(
BRPRE
2
where
>
+
×
VALUE
BR
256
1)
(BR_VALUE
x
BRPRE
2
x
16
PCLK
f
rate
baud
STEP
x
+
=
*
Содержание XC886CLM
Страница 1: ...User s Manual V1 3 2010 02 Microcontrollers 8 Bit XC886 888CLM 8 Bit Single Chip Microcontroller...
Страница 3: ...User s Manual V1 3 2010 02 Microcontrollers 8 Bit XC886 888CLM 8 Bit Single Chip Microcontroller...
Страница 324: ...XC886 888CLM Serial Interfaces User s Manual 12 52 V1 3 2010 02 Serial Interfaces V 1 0...
Страница 663: ...w w w i n f i n e o n c o m Published by Infineon Technologies AG...