Intel 8XC196MH, 8XC196MD, 8XC196MC manual 1 I/O Ports, Serial I/O SIO Port

ARCHITECTURAL OVERVIEW

2.5.1I/O Ports

The 8XC196Mx microcontrollers have seven I/O ports, ports 0–6. The 8XC196MD has an addi- tional port, port 7. Individual port pins are multiplexed to serve as standard I/O or to carry special- function signals associated with an on-chip peripheral or an off-chip component. If a particular special-function signal is not used in an application, the associated pin can be individually con- figured to serve as a standard I/O pin. Ports 3 and 4 are exceptions; they are controlled at the port level, not at the pin level. When the bus controller needs to use the address/data bus, it takes con- trol of the ports. When the address/data bus is idle, you can use the ports for I/O.

Port 0 is an input-only port that is also the analog input for the A/D converter. On the 8XC196MH, port 0 provides two pins for the EPA. On the 8XC196MC and 8XC196MD, port 1 is also an input- only port that provides analog inputs for the A/D converter. On the 8XC196MH, port 1 is a bidi- rectional port that shares pins with the serial I/O port.

Port 2 is a standard, bidirectional I/O port that provides pins for the EPA and timers. Port 7, which is unique to the 8XC196MD, is a standard, bidirectional I/O port that provides additional pins for the EPA and also provides pins for the frequency generator. Ports 3, 4, and 5 are memory-mapped, bidirectional I/O ports. Ports 3 and 4 serve as the external address/data bus, while port 5 provides bus-control signals. Port 6 is a standard, output-only port that provides pins for the pulse-width modulator and waveform generator. Chapter 6, “I/O Ports,” describes the I/O ports in more detail.

2.5.2Serial I/O (SIO) Port

The 8XC196MH microcontroller has a two-channel serial I/O port that shares pins with ports 1 and 2. (The 8XC196MC and 8XC196MD have no serial I/O ports, but have PTS modes that allow asynchronous or synchronous serial communication. See Chapter 5, “Standard and PTS Inter- rupts,” for more information.) The serial I/O (SIO) port is an asynchronous/synchronous port that includes a universal asynchronous receiver and transmitter (UART). The UART has two synchro- nous modes (modes 0 and 4) and three asynchronous modes (modes 1, 2, and 3) for both trans- mission and reception. The asynchronous modes are full duplex, meaning that they can transmit and receive data simultaneously. The receiver is buffered, so the reception of a second byte can begin before the first byte is read. The transmitter is also buffered, allowing continuous transmis- sions. The SIO port has two channels (channels 0 and 1) with identical signals and registers. See Chapter 7, “Serial I/O (SIO) Port,” for details.

2-9