Table of Contents
Advertisement
8XC196NT USER'S MANUAL
2.5.1
I/O Ports
The 8XC196NT has eight I/O ports, ports 0–6 and the EPORT. Individual port pins are multi-
plexed to serve as standard I/O or to carry special-function signals associated with an on-chip pe-
ripheral or an off-chip component. If a particular special-function signal is not used in an
application, the associated pin can be individually configured to serve as a standard I/O pin. Ports
3 and 4 are exceptions. Their pins must be configured either as all I/O or as all address/data.
Port 0 is a four-bit, input-only port that is also the analog input for the A/D converter. Ports 1, 2,
and 6 are eight-bit, bidirectional, standard I/O ports. Port 1 provides I/O pins for the event pro-
cessor array (EPA). Port 2 is used for asynchronous serial I/O (SIO) and bus hold functions. Port
6 is used for synchronous serial I/O (SSIO) and provides additional I/O pins for the EPA. Port 5
is an eight-bit, bidirectional, memory-mapped I/O port. Port 5 pins carry bus-control signals. Data
references to port 5 are always directed internally; therefore, port 5 cannot be reconstructed.
Ports 3 and 4 are eight-bit, bidirectional, memory-mapped I/O ports. These ports can be addressed
only via 16-bit or 24-bit indexed or indirect addresses; they cannot be windowed. Ports 3 and 4
serve as the 16-bit external address/data bus. Port 3 can also serve as the slave port, to provide an
interface between two 8XC196NT family devices or between the 8XC196NT and an external de-
vice. The EPORT provides address lines A19:16 to support extended addressing. See Chapter 6,
"I/O Ports," for more information.
2.5.2
Serial I/O (SIO) Port
The serial I/O (SIO) port is an asynchronous/synchronous port that includes a universal asynchro-
nous receiver and transmitter (UART). The UART has one synchronous mode (mode 0) and three
asynchronous modes (modes 1, 2, and 3) for both transmission and reception. The asynchronous
modes are full duplex, meaning that they can transmit and receive data simultaneously. The re-
ceiver is buffered, so the reception of a second byte may begin before the first byte is read. The
transmitter is also buffered, allowing continuous transmissions. See Chapter 7, "Serial I/O (SIO)
Port," for details.
2.5.3
Synchronous Serial I/O (SSIO) Port
The synchronous serial I/O (SSIO) port provides for simultaneous, bidirectional communications
between two 8XC196 family devices or between an 8XC196 device and another synchronous se-
rial I/O device. The SSIO port consists of two identical transceiver channels with a dedicated
baud-rate generator. The channels can be programmed to operate in several modes. See Chapter
8, "Synchronous Serial I/O (SSIO) Port," for more information.
2-8
Advertisement
Table of Contents
