Toshiba H1 Series User Manual

Page 321

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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,

φT0, φT2, φT8 or φT32, 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

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