guybarash 0 Posted May 14, 2014 Share Posted May 14, 2014 hi, i'm new to the msp430 and i'm using the msp430G2553 on the launchpad. I need a sample code the read distance measure from maxBotix Maxsonar (Lv-MaxSonar-Ez). doesn't really matter what the code does as long as it read distance. thx Quote Link to post Share on other sites
oPossum 1,083 Posted May 15, 2014 Share Posted May 15, 2014 #include <msp430.h> #include <stdint.h> static const unsigned long smclk_freq = 16000000UL; // SMCLK frequency in hertz static const unsigned long bps = 9600UL; // Async serial bit rate static uint32_t upd = 0; // Ultrasonic Pulse Duration (500 ns resolution) // #pragma vector = TIMER1_A1_VECTOR // Timer 1A vectored interrupt __interrupt void timer1_a1_isr(void) // { // static uint32_t rise = 0; // Pulse rise time static uint32_t fall; // Pulse fall time // switch(TA1IV) { // TA0IV must be read to reset interrupt case 0x02: // 0x02 == CCR1 (capture/compare) if(TA1CCTL1 & CCI) { // - Rising edge rise = TA1CCR1; // Save rise time fall = 0; // Reset fall time } else { // - Falling edge if(rise) { // Make sure rising edge has occurred // Handle possible pending overflow interrupt if((TA1CTL & TAIFG) && (TA1CCR0 < 0x1000)) fall += TA1CCR0; // fall += TA1CCR1; // Get fall time, add to overflow time if(!upd) upd = fall - rise; // Update time if mainline code is ready for it rise = 0; // Clear rise time to ensure next rising edge is used } // } // break; // case 0x0A: // 0x0A == TAIFG (overflow) fall += TA1CCR0; // Update overflow time break; // } // } // void putc(const unsigned c) // Output single char to serial { // while(!(IFG2 & UCA0TXIFG)); // Wait for ready (not busy) IFG2 &= ~UCA0TXIFG; // Reset busy flag UCA0TXBUF = c; // Tx char } // // void puts(const char *s) { while(*s) putc(*s++); } // Output string to serial // void print_u32(uint32_t n, const unsigned dp) // Print 32 bit unsigned with optional decimal place // 6 decimal digits (0 -> 999999) { // unsigned c; // c = '0'; while(n >= 100000UL) n -= 100000UL, ++c; putc(c); if(dp == 5) putc('.'); // c = '0'; while(n >= 10000) n -= 10000, ++c; putc(c); if(dp == 4) putc('.'); // c = '0'; while(n >= 1000) n -= 1000, ++c; putc(c); if(dp == 3) putc('.'); // c = '0'; while(n >= 100) n -= 100, ++c; putc(c); if(dp == 2) putc('.'); // c = '0'; while(n >= 10) n -= 10, ++c; putc(c); // if(dp == 1) putc('.'); // c = '0'; while(n) --n, ++c; putc(c); // } // void main(void) // { // WDTCTL = WDTPW | WDTHOLD; // Disable watchdog reset DCOCTL = 0; // Run at 16 MHz BCSCTL1 = CALBC1_16MHZ; // DCOCTL = CALDCO_16MHZ; // // P1DIR = BIT2; // Setup GPIO P1SEL = BIT1 | BIT2; // UART P1SEL2 = BIT1 | BIT2; // // P2OUT = 0; // P2DIR = BIT0; // Timer 1 capture/compare IO P2SEL = BIT0 | BIT1; // P2SEL2 = 0; // // const unsigned long brd = (smclk_freq + (bps >> 1)) / bps; // Bit rate divisor UCA0CTL1 = UCSWRST; // Hold USCI in reset to allow configuration UCA0CTL0 = 0; // No parity, LSB first, 8 bits, one stop bit, UART (async) UCA0BR1 = (brd >> 12) & 0xFF; // High byte of whole divisor UCA0BR0 = (brd >> 4) & 0xFF; // Low byte of whole divisor UCA0MCTL = ((brd << 4) & 0xF0) | UCOS16; // Fractional divisor, oversampling mode UCA0CTL1 = UCSSEL_2; // Use SMCLK for bit rate generator, release reset // // Timer 1 compare 0 TA1CCR0 = (16000000UL / (8 * 2 * 20)) - 1; // 20 Hz (50 ms) TA1CCTL0 = OUTMOD_4; // Toggle mode // Timer 1 capture 1 TA1CCTL1 = CM_3 | SCS | CAP | CCIE; // Rising and falling, sync, capture, interrupt // Timer 1 config TA1CTL = TASSEL_2 | ID_3 | MC_1 | TAIE; // SMCLK, /8, count up, overflow interrupt // _enable_interrupts(); // Enable interrupts // for(; { // For-ever if(upd) { // Check for pulse duration measuement available // Calculate inches const uint32_t in = ((upd * 5534) + (upd >> 1)) >> 14; // Calculate mm const uint32_t mm = (upd * 5623) >> 16; // print_u32(in, 2); // Print inches puts(" in "); // print_u32(mm, 0); // Print mm puts(" mm"); // puts("\r\n"); // upd = 0; // Ready for next } // } // } // GeekDoc, jsolarski and Rickta59 3 Quote Link to post Share on other sites
veryalive 49 Posted May 16, 2014 Share Posted May 16, 2014 @opossum This is what we'd call 'tight code'. Thanks for the lesson. (and good to see you back, btw.) Quote Link to post Share on other sites
guybarash 0 Posted May 21, 2014 Author Share Posted May 21, 2014 thank you you helped a ton Quote Link to post Share on other sites
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