8.5
PROGRAMMING THE SSIO PORT
To use the SSIO port, you must configure the port pins to serve as special-function signals, then
set up the SSIO channels.
8.5.1
Configuring the SSIO Port Pins
Before you can use the SSIO port, you must configure the necessary port 6 pins to serve as their
special-function signals. Handshaking mode requires that both the master and slave SCx pins be
configured as open-drain outputs. (This configuration requires external pull-up resistors.) Table
8-1 on page 8-2 lists the pins associated with the SSIO port, and Table 8-2 lists the port configu-
ration registers. See Chapter 6 for configuration details.
8.5.2
Programming the Baud Rate and Enabling the Baud-rate Generator
The SSIO_BAUD register (Figure 8-5 on page 8-10) defines the baud rate and enables the baud-
rate generator. This register acts as a control register during write operations and as a down-
counter monitor during read operations. The baud-rate generator provides an internal clock to the
transceiver channels. The frequency ranges from F
frequency, this corresponds to a range from a maximum of 2.0 MHz to a minimum of 15.625 kHz.
Table 8-3 lists SSIO_BAUD values for common baud rates.
Table 8-3. Common SSIO_BAUD Values at 16 MHz
(Maximum) 2.0 MHz
(Minimum) 15.625 kHz
†
Bit 7 must be set to enable the baud-rate generator.
Baud Rate
100.0 kHz
64.52 kHz
50.0 kHz
25.0 kHz
SYNCHRONOUS SERIAL I/O (SSIO) PORT
/8 to F
/1024. With a 16-MHz oscillator
OSC
OSC
†
SSIO_BAUD Value
80H
93H
9DH
A7H
CFH
FFH
8-9