Infineon Technologies TC1784, Руководство пользователя

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TC1784
Asynchronous/Synchronous Serial Interface (ASC)
User´s Manual 16-14 V1.1, 2011-05
ASC, V1.6
Using the Fixed Input Clock Divider
The baud rate for asynchronous operation of the serial channel ASC when using the
fixed input clock divider ratios (CON.FDE = 0) and the required BG reload value for a
given baud rate can be determined by the following formulas:
BG represents the content of the reload register bit field BG.BR_VALUE, taken as an
unsigned 13-bit integer.
The maximum baud rate that can be achieved for the asynchronous operating modes
when using the two fixed clock dividers and a module clock of 90 MHz is 2.8125 Mbit/s.
Table 16-2 lists various commonly used baud rates together with the required reload
values and the deviation errors compared to the intended baud rate.
Note: CON.FDE must be 0 to achieve the baud rates in the table above. The deviation
errors given in the table are rounded. Using a baud rate crystal will provide correct
baud rates without deviation errors.
Table 16-1 Asynchronous Baud Rate Formulas using the Fixed Input Clock
Dividers
FDE BRS BG Formula
0 0 0 … 8191
1
Table 16-2 Typical Asynchronous Baud Rates using Fixed Input Clock Dividers
Baud Rate CON.BRS = 0,
f
ASC
= 90 MHz CON.BRS = 1,
f
ASC
= 90 MHz
Deviation Error Reload Value Deviation Error Reload Value
2.8125 Mbit/s – 0000
H
– –
19.2 kbit/s +0.3% / -0.4% 0091
H
/ 0092
H
+0.9% / -0.4% 0060
H
/ 0061
H
9600 bit/s +0.0% / -0.3% 0123
H
/ 0124
H
+0.2% / -0.4% 00C2
H
/ 00C3
H
4800 bit/s +0.2% / -0.0% 0248
H
/ 0249
H
+0.2% / -0.1% 0185
H
/ 0186
H
Baud rate
f
ASC
32 BG 1 +
( ) ×
------------------------------------ =
BG
f
ASC
32 Baud rate
×
--------------------------------------- 1
– =
Baud rate
f
ASC
48
BG 1 +
( ) ×
------------------------------------- =
BG
f
ASC
48
Baud rate
×
--------------------------------------- 1
– =