MC68306FC16 Datasheet, PDF (115/191 Pages) Motorola, Inc – Integrated EC000 Processor

6.3 OPERATION
The following paragraphs describe the operation of the baud rate generator, transmitter
and receiver, and other functional operating modes of the serial module.
6.3.1 Baud Rate Generator
The baud rate generator consists of a crystal oscillator, baud rate generator, and clock
selectors (see Figure 6-3). The crystal oscillator operates directly from a 3.6864-MHz
crystal or from an external clock of the same frequency. Baud rates are selected by
programming the clock-select register (DUCSR) for each channel.
BAUD RATE
GENERATOR LOGIC
CRYSTAL
OSCILLATOR
BAUD RATE
GENERATOR
EXTERNAL
.INTERFACE
X1
X2
CLOCK
SELECTORS
Figure 6-3. Baud Rate Generator Block Diagram
6.3.2 Transmitter and Receiver Operating Modes
The functional block diagram of the transmitter and receiver, including command and
operating registers, is shown in Figure 6-4. The paragraphs that follow contain
descriptions for both these functions in reference to this diagram. For detailed register
information, refer to 6.4 Register Description and Programming.
MOTOROLA
MC68306 USER'S MANUAL
6-7