msp430x11x1串口通信.cpp

LCD_disp是针对SMS0810B型号液晶的汇编语言；其他的是与430单片机有关的C代码

//******************************************************************************
// MSP430x11x1 Demo - Timer_A, UART 9600 Echo, HF XTAL ACLK
//
// Description: Use Timer_A CCR0 hardware output modes and SCCI data latch
// to implement UART function @ 9600 baud. Software does not directly read and
// write to RX and TX pins, instead proper use of output modes and SCCI data
// latch are demonstrated. Use of these hardware features eliminates ISR
// latency effects as hardware insures that output and input bit latching and
// timing are perfectly synchronised with Timer_A regardless of other
// software activity. In the Mainloop the UART function readies the UART to
// receive one character and waits in LPM0 with all activity interrupt driven.
// After a character has been received, the UART receive function forces exit
// from LPM0 in the Mainloop which echo's back the received character.
// ACLK = MCLK = TACLK = HF XTAL = 3.579545MHz
// //* An external 3.579545Hz XTAL on XIN XOUT is required for ACLK *// 
//
// MSP430F1121
// -----------------
// /|\| XIN|-
// | | | 3.58Mhz
// --|RST XOUT|-
// | |
// | CCI0A/TXD/P1.1|-------->
// | | 9600 8N1
// | CCI0B/RXD/P2.2|<--------
//
#define RXD 0x04 // RXD on P2.2
#define TXD 0x02 // TXD on P1.1

// Conditions for 9600 Baud HW/SW UART, ACLK = 3.579545MHz

#define Bitime_5 0x0BA // ~ 0.5 bit length
#define Bitime 0x175 // 104 us ~ 9596 baud

unsigned int RXTXData;
unsigned char BitCnt;

void TX_Byte (void);
void RX_Ready (void);

// M. Buccini
// Texas Instruments Inc.
// Feb 2005
// Built with IAR Embedded Workbench Version: 3.21A
//*****************************************************************************

#include <msp430x11x1.h>


void main (void)
{
	volatile unsigned int i;
	WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer

	BCSCTL1 |= XTS; // ACLK = LFXT1 = HF XTAL

	do
	{
		IFG1 &= ~OFIFG; // Clear OSCFault flag
		for (i = 0xFF; i > 0; i--); // Time for flag to set
	}
	while ( IFG1 & OFIFG ); // OSCFault flag still set?

	BCSCTL2 |= SELM_3; // MCLK = LFXT1 (safe)

	CCTL0 = OUT; // TXD Idle as Mark
	TACTL = TASSEL_1 + MC_2; // ACLK, continuous mode
	P1SEL = TXD; // P1.1/TA0 for TXD function
	P1DIR = TXD; // TXD output on P1
	P2SEL = RXD; // P2.2/TA0 as RXD input

// Mainloop
	for (;;)
	{
	RX_Ready(); // UART ready to RX one Byte
	_BIS_SR(CPUOFF + GIE); // Enter LPM0 w/ interr until char RXed
	TX_Byte(); // TX Back RXed Byte Received
	}
}


// Function Transmits Character from RXTXData Buffer
void TX_Byte (void)
{
	BitCnt = 0xA; // Load Bit counter, 8data + ST/SP
	CCR0 = TAR; // Current state of TA counter
	CCR0 += Bitime; // Some time till first bit
	RXTXData |= 0x100; // Add mark stop bit to RXTXData
	RXTXData = RXTXData << 1; // Add space start bit
	CCTL0 = OUTMOD0 + CCIE; // TXD = mark = idle
	while ( CCTL0 & CCIE ); // Wait for TX completion
}


// Function Readies UART to Receive Character into RXTXData Buffer
void RX_Ready (void)
{
	BitCnt = 0x8; // Load Bit counter
	CCTL0 = SCS + CCIS0 + OUTMOD0 + CM1 + CAP + CCIE; // Sync, Neg Edge, Capture
}


// Timer A0 interrupt service routine
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A (void)
{
	CCR0 += Bitime; // Add Offset to CCR0

	// RX
	if (CCTL0 & CCIS0) // RX on CCI0B?
	{
		if( CCTL0 & CAP ) // Capture mode = start bit edge
		{
			CCTL0 &= ~ CAP; // Switch from capture to compare mode
			CCR0 += Bitime_5;
		}
		else
		{
			RXTXData = RXTXData >> 1;
			if (CCTL0 & SCCI) // Get bit waiting in receive latch
				RXTXData |= 0x80;
			BitCnt --; // All bits RXed?
			if ( BitCnt == 0)
//>>>>>>>>>> Decode of Received Byte Here <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
			{
				CCTL0 &= ~ CCIE; // All bits RXed, disable interrupt
				_BIC_SR_IRQ(CPUOFF); // Clear LPM0 bits from 0(SR)
			}
//>>>>>>>>>> Decode of Received Byte Here <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
		}
	}
// TX
	else
	{
		if ( BitCnt == 0)
			CCTL0 &= ~ CCIE; // All bits TXed, disable interrupt
		else
		{
			CCTL0 |= OUTMOD2; // TX Space
			if (RXTXData & 0x01)
			CCTL0 &= ~ OUTMOD2; // TX Mark
			RXTXData = RXTXData >> 1;
			BitCnt --;
		}
	}
}