Siemens EF 88H Series Bedienungsanleitung PDF herunterladen (Seite 49)

Semiconductor Group 5 - 14

On-Chip Peripheral Components

5.4 New Baud Rate Generators for Serial Channel 0 and Serial Channel 1

5.4.1 Serial Channel 0 Baud Rate Generator

The Serial Channel 0 has a new baud rate generator which provides greater flexibility and better

resolution. It substitutes the 80C517’s baud rate generator at Serial Channel 0 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 5-4 shows a block diagram of the new baud rate generator for Serial Channel 0. 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 S0RELL (address AA

) and S0RELH (address BA

). The

lower 8 bits of the timer are reloaded from S0RELL, while the upper two bits are reloaded from bit

0 and 1 of register S0RELH. The baud rate timer is reloaded by writing to S0RELL.

Figure 5-4

Baud Rate Generator for Serial Interface 0

The default value after reset of S0RELL is 0D9

, S0 RELH contains XXXX XX11B.

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Siemens EF 88H Series Bedienungsanleitung Seite 49