saf-xc866-4rri3v Infineon Technologies Corporation, saf-xc866-4rri3v Datasheet - Page 75

• Manufacturer Part Number: saf-xc866-4rri3v
• Description: 8-bit Single-chip Microcontroller
• Manufacturer: Infineon Technologies Corporation

3.11.2
In UART modes 1 and 3, Timer 1 can be used for generating the variable baud rates. In
theory, this timer could be used in any of its modes. But in practice, it should be set into
auto-reload mode (Timer 1 mode 2), with its high byte set to the appropriate value for the
required baud rate. The baud rate is determined by the Timer 1 overflow rate and the
value of SMOD as follows:
3.12
Setting bit FDM in register FDCON to 1 configures the fractional divider to normal divider
mode, while at the same time disables baud rate generation (see
fractional divider is enabled (FDEN = 1), it functions as an 8-bit auto-reload timer (with
no relation to baud rate generation) and counts up from the reload value with each input
clock pulse. Bit field RESULT in register FDRES represents the timer value, while bit
field STEP in register FDSTEP defines the reload value. At each timer overflow, an
overflow flag (FDCON.NDOV) will be set and an interrupt request generated. This gives
an output clock
The output frequency in normal divider mode is derived as follows:
Data Sheet
Baud Rate Generation using Timer 1
Normal Divider Mode (8-bit Auto-reload Timer)
f
MOD
that is 1/n of the input clock
Mode 1, 3 baud rate
f
MOD
=
f
DIV
71
=
---------------------------------------------------- -
32 2
×
----------------------------- -
256 STEP
2
×
f
SMOD
DIV
–
×
, where n is defined by 256 - STEP.
1
(
256 TH1
×
f
PCLK
–
Functional Description
)
Figure
29). Once the
V1.2, 2007-10
XC866
[3.1]
[3.2]