Micronas SDA 6000, User Manual

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SDA 6000
PRELIMINARY DATA SHEET
Version 2.1
Peripherals
7 - 92 Micronas
7.4.4 Port Control
The SSC0 uses three pins to communicate with the external world. Pin SCLK serves as
the clock line, while pins MRST (Master Receive/Slave Transmit) and MTSR (Master
Transmit/Slave Receive) serve as the serial data input/output lines.
The operation of the SSC0 pins depends on the selected operating mode (master or
slave). The direction of the port lines depends on the operating mode. The SSC0 will
automatically use the correct alternate input or output line of the ports when switching
modes. The direction of the port pins, however, must be programmed by the user. Using
the open drain output feature of the port lines helps to avoid bus contention problems
and reduces the need for hardwired hand-shaking or slave select lines. In this case it is
not always necessary to switch the direction of a port pin.
7.4.5 Baud Rate Generation
The serial channel SSC0 has its own dedicated 16-bit baud rate generator with 16-bit
reload capability, allowing baud rate generation independent from the timers. In addition
to
Figure 7-39 , Figure 7-43 shows the baud rate generator of the SSC0 in more detail.
Figure 7-43 SSC0 Baud Rate Generator
The baud rate generator is clocked with the module clock 33.33 MHz. The timer is
counting downwards. Register SSCBR is the dual-function Baud Rate Generator/Reload
register. Reading SSCBR, while the SSC0 is enabled, returns the content of the timer.
Reading SSCBR, while the SSC0 is disabled, returns the programmed reload value. In
this mode the desired reload value can be written to SSCBR.
Note: Never write to SSCBR, while the SSC0 is enabled.
UES11162
16-Bit Reload Register
16-Bit Counter
f
SCLK
2 ÷ 33 MHz
SCLKmax
f
in master mode
_ < 33 MHz / 2
in slave mode
SCLKmax
f
33 MHz / 4
< _