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Software UART

Software UART is seldom needed but it comes really useful in absence of hardware UART. In some

cases, we may not have the luxury of using hardware UART. Hardware UART block may also be absent.

We already know that USCI module can be used for implementing hardware UART but this block is not

present in chips like MSP430G2452. In such devices, we have to use software-generated UART.

Software UART uses ordinary digital I/Os and delays. Both additionally and optionally external

interrupts and timers can be used for better results. Owing to its hardware independency and

simplicity, it is very robust. However extra coding and therefore extra memory spaces are needed.

Code Example

SW_UART.h

#include <msp430.h>

#include "delay.h"

#define SW_UART_RXD_DIR P1DIR

#define SW_UART_TXD_DIR P1DIR

#define SW_UART_RXD_OUT P1OUT

#define SW_UART_TXD_OUT P1OUT

#define SW_UART_RXD_IN P1IN

#define SW_UART_RXD_IN_RES P1REN

#define SW_UART_RXD_PIN BIT1

#define SW_UART_TXD_PIN BIT2

#define SW_UART_RXD_DIR_IN() do{SW_UART_RXD_OUT |= SW_UART_RXD_PIN;

SW_UART_RXD_DIR &= ~SW_UART_RXD_PIN; SW_UART_RXD_IN_RES |=

SW_UART_RXD_PIN;}while(0)

#define SW_UART_TXD_DIR_OUT() do{SW_UART_TXD_DIR |= SW_UART_TXD_PIN;}while(0)

#define SW_UART_TXD_OUT_HIGH() do{SW_UART_TXD_OUT |= SW_UART_TXD_PIN;}while(0)

#define SW_UART_TXD_OUT_LOW() do{SW_UART_TXD_OUT &= ~SW_UART_TXD_PIN;}while(0)

#define SW_UART_RXD_INPUT() (SW_UART_RXD_IN & SW_UART_RXD_PIN)

Texas Instruments MSP430 User Manual

Other manuals for Texas Instruments MSP430