SERIAL I/O (SIO) PORT

Table 8-2. Serial Port Control and Status Registers (Continued)

Mnemonic

Address

Description

 

 

 

P1_PIN

1FD6H

Port 1 Pin State

 

 

If you are using T1CLK (P1.4) as the clock source for the baud-rate

 

 

generator, you can read P1_PIN.4 to determine the current value of

 

 

T1CLK.

 

 

 

P1_REG

1FD4H

Port 1 Output Data

 

 

To use T1CLK as the clock source for the baud-rate generator, set

 

 

P1_REG.4.

 

 

 

P2_DIR

1FCBH

Port 2 Direction

 

 

This register selects the direction of each port 2 pin. Clear P2_DIR.1

 

 

to configure RXD (P2.1) as a high-impedance input/open-drain

 

 

output, and set P2_DIR.0 to configure TXD (P2.0) as a comple-

 

 

mentary output.

 

 

 

P2_MODE

1FC9H

Port 2 Mode

 

 

This register selects either the general-purpose input/output function

 

 

or the peripheral function for each pin of port 2. Set P2_MODE.1:0

 

 

to configure TXD (P2.0) and RXD (P2.1) for the SIO port.

 

 

 

P2_PIN

1FCFH

Port 2 Pin State

 

 

Two bits of this register contain the values of the TXD (P2.0) and

 

 

RXD (P2.1) pins. Read P2_PIN to determine the current value of the

 

 

pins.

 

 

 

P2_REG

1FCDH

Port 2 Output Data

 

 

This register holds data to be driven out on the pins of port 2. Set

 

 

P2_REG.1 for the RXD (P2.1) pin. Write the desired output data for

 

 

the TXD (P2.0) pin to P2_REG.0.

 

 

 

SBUF_RX

1FB8H

Serial Port Receive Buffer

 

 

This register contains data received from the serial port.

 

 

 

SBUF_TX

1FBAH

Serial Port Transmit Buffer

 

 

This register contains data that is ready for transmission. In modes

 

 

1, 2, and 3, writing to SBUF_TX starts a transmission. In mode 0,

 

 

writing to SBUF_TX starts a transmission only if the receiver is

 

 

disabled (SP_CON.3 = 0)

 

 

 

SP_BAUD

1FBCH,1FBDH

Serial Port Baud Rate

 

 

This register selects the serial port baud rate and clock source. The

 

 

most-significant bit selects the clock source. The lower 15 bits

 

 

represent the BAUD_VALUE, an unsigned integer that determines

 

 

the baud rate.

 

 

 

SP_CON

1FBBH

Serial Port Control

 

 

This register selects the communications mode and enables or

 

 

disables the receiver, parity checking, and ninth-bit data transmis-

 

 

sions. The TB8 bit is cleared after each transmission.

 

 

 

8-3

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Intel Microcontroller, 80C196NU, 8XC196NP manual P1REG 1FD4H, Sbufrx 1FB8H, Sbuftx 1FBAH, Spbaud 1FBCH,1FBDH, Spcon 1FBBH

Microcontroller, 80C196NU, 8XC196NP specifications

The Intel 8XC196NP and 80C196NU microcontrollers are part of Intel's renowned 16-bit microcontroller series that gained popularity in the 1980s and 1990s for embedded systems applications. Designed for a variety of applications, these microcontrollers are characterized by their robust performance, versatility, and industry-standard architecture.

The 8XC196NP features an enhanced instruction set with over 100 instructions, allowing for efficient code execution. It operates at clock speeds up to 16 MHz, which contributes to improved performance in time-sensitive applications. The microcontroller is equipped with a 16-bit data bus, enabling more efficient data handling compared to its 8-bit predecessors, thus accommodating complex algorithms and large data sets.

In terms of memory architecture, the 8XC196NP supports an addressable memory space of up to 64 KB of program memory and 64 KB of data memory. This configuration provides sufficient space for large applications while ensuring fast data access. The microcontroller includes integrated features such as timers, serial I/O capabilities, and interrupt processing, which enhance its functionality for real-time applications and control mechanisms.

The 80C196NU, on the other hand, is designed for lower power operation, making it suitable for battery-powered devices. This microcontroller maintains similar features to the 8XC196NP while offering advancements that support low-power consumption. The 80C196NU can also function in a range of temperature environments, making it adaptable for industrial applications.

Both the 8XC196NP and 80C196NU support external memory interfacing, allowing designers to expand the system's capability by connecting additional ROM and RAM. This flexibility makes them appealing for developing complex systems, such as motor controls, industrial automation, and consumer electronics.

Another standout feature of these microcontrollers is their built-in debugging capabilities. Intel provided hardware and software tools that enabled developers to test and troubleshoot their applications effectively, reducing the development time and increasing reliability.

Overall, the Intel 8XC196NP and 80C196NU microcontrollers stand out for their dependability, versatility, and performance, contributing significantly to the evolution of embedded system design. Their legacy continues to influence modern microcontroller technology, ensuring their relevance in a wide array of applications today.