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127 lines
5.7 KiB
127 lines
5.7 KiB
/*******************************************************************************
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*
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* uart.c - c file for UART communication using MSP430 TimerA
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* - peripheral
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*
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* Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* Neither the name of Texas Instruments Incorporated nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*
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******************************************************************************/
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#include "uart.h"
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unsigned char timerA_UART_mode = 0;
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unsigned int txData;
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//------------------------------------------------------------------------------
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// Function configures Timer_A for full-duplex UART operation
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//------------------------------------------------------------------------------
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void TimerA_UART_init(void)
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{
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DCOCTL = 0x00; // Set DCOCLK to 1MHz
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BCSCTL1 = CALBC1_1MHZ;
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DCOCTL = CALDCO_1MHZ;
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BCSCTL2 &= ~DIVS_3; // SMCLK = 1MHz
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P1SEL |= UART_TXD + UART_RXD; // Timer function for TXD/RXD pins
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// P1SEL |= UART_TXD ;
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P1DIR |= UART_TXD; // TXD
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P1DIR &= ~UART_RXD;
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TACCTL0 = OUT; // Set TXD Idle as Mark = '1'
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// TACCTL1 = SCS + CM1 + CAP + CCIE; // Sync, Neg Edge, Capture, Int
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TACTL |= TACLR; // SMCLK, start in continuous mode
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TACTL = TASSEL_2 + MC_2; // SMCLK, start in continuous mode
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timerA_UART_mode = 1;
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}
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//------------------------------------------------------------------------------
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// Function unconfigures Timer_A for full-duplex UART operation
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//------------------------------------------------------------------------------
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void TimerA_UART_shutdown(void)
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{
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timerA_UART_mode = 0;
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P1SEL &= ~(UART_TXD + UART_RXD); // Timer function for TXD/RXD pins
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// P1SEL &= ~(UART_TXD ); // Timer function for TXD/RXD pins
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TACCTL1 &= ~CCIE; // Sync, Neg Edge, Capture, Int
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TACTL &= ~MC_3; // Clear TA modes --> Stop Timer Module
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P1OUT &= ~UART_TXD;
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}
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//------------------------------------------------------------------------------
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// Outputs one byte using the Timer_A UART
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//------------------------------------------------------------------------------
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void TimerA_UART_tx(unsigned char byte)
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{
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while (TACCTL0 & CCIE); // Ensure last char got TX'd
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TACCR0 = TAR; // Current state of TA counter
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TACCR0 += UART_TBIT; // One bit time till first bit
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txData = byte; // Load global variable
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txData |= 0x100; // Add mark stop bit to TXData
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txData <<= 1; // Add space start bit
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TACCTL0 = OUTMOD0 + CCIE; // Set TXD on EQU2 (idle), Int
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__bis_SR_register( LPM0_bits + GIE);
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}
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//------------------------------------------------------------------------------
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// Prints a string over using the Timer_A UART
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//------------------------------------------------------------------------------
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void TimerA_UART_print(char *string)
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{
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while (*string) {
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TimerA_UART_tx(*string++);
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}
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}
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//------------------------------------------------------------------------------
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// Timer_A UART - Transmit Interrupt Handler
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//------------------------------------------------------------------------------
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#pragma vector = TIMER0_A0_VECTOR
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__interrupt void Timer_A0_ISR(void)
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{
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static unsigned char txBitCnt = 10;
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if (!timerA_UART_mode)
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__bic_SR_register_on_exit(LPM3_bits+GIE);
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else
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{
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TACCR0 += UART_TBIT; // Add Offset to CCRx
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if (--txBitCnt == 0) // All bits TXed?
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{
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TACCTL0 &= ~CCIE; // All bits TXed, disable interrupt
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txBitCnt = 10;
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__bic_SR_register_on_exit(LPM0_bits+GIE);
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}
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else {
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if (txData & 0x01) {
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TACCTL0 &= ~OUTMOD2; // TX Mark '1'
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}
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else {
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TACCTL0 |= OUTMOD2; // TX Space '0'
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}
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txData >>= 1;
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}
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}
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}
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