TMP92CZ26A
92CZ26A-318
(2) Baud rate generator
The baud rate generator is the circuit which generates transmission/receiving clock
and determines the transfer rate of the serial channels.
The input clock to the baud rate generator,
φ
T0,
φ
T2,
φ
T8 or
φ
T32, is generated by
the 6-bit prescaler which is shared by the timers. One of these input clocks is selected
using the BR0CR<BR0CK1:0> field in the baud rate generator control register.
The baud rate generator includes a frequency divider, which divides the frequency
by 1 or N
+
(16
−
K)/16 to 16 values, determining the transfer rate.
The transfer rate is determined by the settings of BR0CR<BR0ADDE, BR0S3:0>
and BR0ADD<BR0K3:0>.
•
In UART mode
When BR0CR<BR0ADDE>
=
0
The settings BR0ADD<BR0K3:0> are ignored. The baud rate generator divides
the selected prescaler clock by N, which is set in BR0CK<BR0S3:0>. (N
=
1, 2, 3 ...
16)
When BR0CR<BR0ADDE>
=
1
The N
+
(16
−
K)/16 division function is enabled. The baud rate generator
divides the selected prescaler clock by N
+
(16 – K)/16 using the value of N set in
BR0CR<BR0S3:0> (N
=
2, 3 ... 15) and the value of K set in BR0ADD<BR0K3:0>
(K
=
1, 2, 3 ... 15)
Note: If N
=
1 or N
=
16, the N
+
(16
−
K)/16 division function is disabled. Clear
BR0CR<BR0ADDE> to 0.
•
In I/O interface mode
The N
+
(16
−
K)/16 division function is not available in I/O interface mode. Clear
BR0CR<BR0ADDE> to 0 before dividing by N.
The method for calculating the transfer rate when the baud rate generator is used is
explained below.
•
In UART mode
Baud rate
=
÷
16
•
In I/O interface mode
Baud
rate
=
÷
2
Input clock of baud rate generator
Frequency divider for baud rate generator
Input clock of baud rate generator
Frequency divider for baud rate generator