TC1796
Peripheral Units (Vol. 2 of 2)
Asynchronous/Synchronous Serial Interface (ASC)
User’s Manual 19-16 V2.0, 2007-07
ASC, V2.0
19.1.5.2 Baud Rates in Synchronous Mode
For synchronous operation, the baud rate generator provides a clock f
BRT
that runs with
four times the established baud rate (see Figure 19-9).
Figure 19-9 ASC Baud Rate Generator Circuitry in Synchronous Mode
The baud rate for synchronous operation of the serial channel ASC can be determined
by the formulas as shown in Table 19-5.
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 in Synchronous Mode when using a
module clock of 75 MHz is 9.38 Mbit/s.
Table 19-5 Synchronous Baud Rate Formulas
BRS BG Formula
0 0 … 8191
1
MCA05770
13-Bit Baud Rate Timer
Shift /
Sample
Clock
13-Bit Reload Register
BRS
f
BRT
f
DIV
R
f
ASC
2
BRS
0
1
Selected Divider
3
MUX
2
3
4
Baud rate
f
ASC
8BG1+()×
---------------------------------=
BG
f
ASC
8 Baud rate×
-----------------------------------
1–=
Baud rate
ASC
12 BG 1+()×
------------------------------------=
BG
ASC
12 Baud rate×
---------------------------------------
1–=
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