C508_01 Datasheet, PDF (175/267 Pages) Infineon Technologies AG – 8-Bit CMOS Microcontroller

C508
On-Chip Peripheral Components
6.4.3.3.2 Using Timer 1 to Generate Baudrates
When Timer 1 is used as the baudrate generator in Modes 1 and 3, the baudrates are
determined by the Timer 1 overflow rate and the value of SMOD as follows:
Mode 1, 3 baudrate = ^2SMOD
32
× (Timer 1 overflow rate)
The Timer 1 interrupt should be disabled in this application. Timer 1, itself, can be
configured for either “timer” or “counter” operation, and in any of its operating modes. In
most typical applications, it is configured for “timer” operation in the auto-reload mode
(high nibble of TMOD = 0010_B). In this case the baudrate is given by the formula:
2^{SMOD ×} oscillator frequency
Mode 1, 3 baudrate =
32 × 3 × (256 - (TH1))
Very low baudrates can be achieved with Timer 1 by leaving the Timer 1 interrupt
enabled, and configuring the timer to run as 16-bit timer (high nibble of TMOD = 0001_B),
and using the Timer 1 interrupt for a 16-bit software reload.
User’s Manual
6-110
2001-05