SAB80C515A-5 Datasheet, PDF (41/108 Pages) Siemens Semiconductor Group – 8-Bit CMOS Single-Chip Microcontroller Family

On-Chip Peripheral Components
5.2 New Baud Rate Generator for Serial Channel
The Serial Channel has a new baud rate generator which provides greater flexibility and better
resolution. It substitutes the 80C515’s baud rate generator at the Serial Channel which provides
only 4.8 kBaud or 9.6 kBaud at 12 MHz crystal frequency. Since the new generator offers greater
flexibility it is often possible to use it instead of Timer1 which is then free for other tasks.
Figure 5-3 shows a block diagram of the new baud rate generator for the Serial Channel. It consists
of a free running 10-bit timer with f_OSC / 2 input frequency. On overflow of this timer there is an
automatic reload from the registers SRELL (address AAH) and SRELH (address BAH). The lower
8 bits of the timer are reloaded from SRELL, while the upper two bits are reloaded from bit 0 and 1
of register SRELH. The baud rate timer is reloaded by writing to SRELL.
Figure 5-4
Baud Rate Generator for the Serial Interface
Semiconductor Group
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