MSP430 Launchpad(MSP430G2231)开发板控制 数显游标卡尺

　　(原文件名:3.png)
　　这是代码，供大家参考：
　　//*******************************************
　　// Running on Launchpad
　　// MSP430G2231
　　// ------------------
　　// /|| XIN|-
　　// | | |
　　// --|RST XOUT|-
　　// | |
　　// Vin+ -->|A1+ P1.2 |
　　// |A1- = VSS P1.0|-->LED
　　// | P1.1|-->TX RS232
　　// | P1.4|<--CLOCK CALIPER
　　// | P1.5|<--DATA CALIPER
　　//
　　//*******************************************
　　#include
　　int value = 0; // value received from caliper
　　unsigned char clock_active = 0; // any clock activity during last 32msec?
　　unsigned char ready_for_data = 0;// idle between clock burts, ready for next one
　　unsigned char bits_so_far = 0; // current bit count during value "assembly"
　　// how many CPU cycles between bits
　　#define Bitime 104 //9600 Baud, SMCLK=1MHz (1MHz/9600)=104
　　unsigned char BitCnt; // Bit count, used when transmitting byte
　　unsigned int TXByte; // Value sent over UART when Transmit() is called
　　#define LED BIT0 // LED on P1.0
　　#define TXPIN BIT1 // RS232 TX on P1.1
　　#define CLOCK BIT4 // Clock on P1.4
　　#define DATA BIT5 // Data on P1.5
　　void Transmit(void);
　　void main(void)
　　{
　　DCOCTL = 0x00; // Safe Flow
　　BCSCTL1 = CALBC1_1MHZ; // run at 1Mhz
　　DCOCTL = CALDCO_1MHZ;
　　//WDT as 32 ms interval counter. If no action on clock withing 32msec,
　　// we are ready to receive next "number"
　　WDTCTL = WDT_MDLY_32; // default timer 32 msec
　　IE1 |= WDTIE; // Enable WDT interrupt
　　P1DIR |= LED; // Set P1.0 to output direction
　　P1OUT |= LED; // LED ON, we'r ready
　　P1SEL |= TXPIN;
　　P1DIR |= TXPIN; // Set P1.1 to output direction
　　// Set up CLOCK input pin
　　P1DIR &= ~CLOCK; // sets input direction
　　P1OUT |= CLOCK; // pull-up is selected
　　P1REN |= CLOCK; // pull-up/pull-down enabled
　　P1IES &= ~CLOCK; // interupt triggered on low-to-high
　　P1IFG &= ~CLOCK; // reset interup flag to 0. needs to be reset on start
　　P1IE |= CLOCK; // interupt enabled for CLOCK
　　// Set up DATA input pin
　　P1DIR &= ~DATA; // sets input direction
　　P1OUT |= DATA; // pull-up is selected
　　P1REN |= DATA; // pull-up/pull-down enabled
　　P1IES &= ~DATA; // interupt triggered on low-to-high
　　P1IFG &= ~DATA; // reset interup flag to 0. nneds to be reset on start
　　P1IE &= ~DATA; // interupt disabled for DATA
　　// sending something over serial
　　while (1)
　　{
　　__bis_SR_register(LPM0_bits + GIE);
　　// after we went into low power mode, program counter is at this instruction
　　// (next one after where you entered LPM), but it's not moving until you enable active mode
　　// within main loop. That can be done with __bic_SR_register_on_exit(LPM0_bits) in ISR
　　_NOP();
　　// seding next value. value has been assambled by CLOCL interupt function
　　// value is 16 bit, TXByte should be 8, sending in two parts
　　TXByte = value >> 8; // first byte (most significant bits)
　　Transmit();
　　TXByte = value & 0xFF; // second byte (least significant)
　　Transmit();
　　P1OUT ^= LED; // blink LED
　　}
　　}
　　// Function Transmits Character from TXByte
　　void Transmit()
　　{
　　CCTL0 = OUT; // TXD Idle as Mark
　　TACTL = TASSEL_2 + MC_2; // SMCLK, continuous mode
　　BitCnt = 0xA; // Load Bit counter, 8 bits + ST/SP
　　CCR0 = TAR;
　　CCR0 += Bitime; // Set time till first bit
　　TXByte |= 0x100; // Add stop bit to TXByte (which is logical 1)
　　TXByte = TXByte << 1; // Add start bit (which is logical 0)
　　CCTL0 = CCIS0 + OUTMOD0 + CCIE; // Set signal, intial value, enable interrupts
　　while ( CCTL0 & CCIE ); // Wait for TX completion
　　TACTL = TASSEL_2; // SMCLK, timer off (for power consumption)
　　}
　　// Timer A0 interrupt service routine. Used to send bits over RS232
　　#pragma vector=TIMERA0_VECTOR
　　__interrupt void Timer_A (void)
　　{
　　CCR0 += Bitime; // Add Offset to CCR0
　　if ( BitCnt == 0) // If all bits TXed, disable interrupt
　　CCTL0 &= ~ CCIE;
　　else
　　{
　　CCTL0 |= OUTMOD2; // TX Space
　　if (TXByte & 0x01)
　　CCTL0 &= ~ OUTMOD2; // TX Mark
　　TXByte = TXByte >> 1;
　　BitCnt --;
　　}
　　}
　　// Button is pressed
　　#pragma vector=PORT1_VECTOR
　　__interrupt void PORT1_ISR(void)
　　{
　　static unsigned char port;
　　port = P1IN; // read DATA port value as soon as possible (otherwise it might be gone)
　　P1IFG &= ~CLOCK; // Clear interrupt flag
　　clock_active = 1;
　　if (ready_for_data)
　　{
　　if (bits_so_far && bits_so_far <= 16){ // first bit is start bit, ignore it. Total we have 24 bits. But we need only 16
　　if (!(port & DATA)) // if 0 recived, invert = >1
　　value |=0x8000; // then set most significant bit
　　value = value >> 1; // and move it one right
　　}else if (bits_so_far == 21){ // 21st bit indicates sighn (+/-)
　　if (!(port & DATA))
　　value = (~value)+1; // make it negative
　　}else if (bits_so_far >= 23){ // we'r done, got all bits
　　ready_for_data = 0; // warchdog timer will set it
　　__bic_SR_register_on_exit(LPM0_bits); // wake up main from LPM sleep
　　}
　　bits_so_far++;
　　}
　　}
　　// watchdog used as 30msec timer for detecting start of new bit burst on clock
　　#pragma vector=WDT_VECTOR
　　__interrupt void WDT_ISR(void)
　　{
　　if (ready_for_data)
　　return;
　　if (clock_active){
　　clock_active = 0; // clear flag, will wait another 32msec to see if there have been any activity of clock
　　ready_for_data = 0; // not yet ready
　　}else{
　　ready_for_data = 1; // nothing within last 32msec, ready for next clock burst
　　value = 0; // init of value
　　bits_so_far = 0; // init of bit counter
　　}
　　}