Generating a 1 Pulse Per Second using MSP430 - Page 1
Forum section: electronics / general

author: omerdf
author_rank: Newbie
timestamp: December 11, 2016, 10:16:04 am
content: Hello ,I'm using MSP430F5131.I'm new to all this msp430 and microcontroller field in general.I need help to write the code for my project with the following conditions:I will explain a little about the project :My main goal is to generate a 1 pulse per second using a duty cycle of 50% by a 12.8MHz external oscillator.I already have a printed PCB for that project which means i got to understand what the previous designer had done and implement it into my CCS program in order to program my micro controller.i am still new to this whole microcontroller world and im eager to know more , although im short in time.I have attached an electrical wiring of the PCB to help you understand a little bit more about the project.A little explanation of the electrical wiring:An external toggle switch (from connector J6 "Internal/External Selection") switch between an external 1pps (From an external GPS) or internal 1pps (by the msp430).if we choose an internal mode then (input P2.2) a '1' (or '0' if its an active low mode which is an active low mode) sends from PJ.3 (ouput) to U4 and a 1 pulse per second gets out of P2.4 output to connectors J8 and J9 (same pulse different connectors).I can Switch signals to ON/BAD/OFF by using an external toggle switch(pins 1,2 of J3 connector) or a descrete (pin 3 of J3 connector).if i toggle the switch to on mode it sends '1'(or '0' if its an active low mode which is an active low mode) through P1.6 to U5 ( And Gate) and enables the pulse it also sends '1' through PJ.0 to U6 and converts the pulse from TTL to RS422 (differetial).The descrete switching option switches the pulse (ON/OFF) the same as the external toggle switch.This is refers to PULSE 1 , i need to implement the same thing for PULSE 2.although im still not sure what RST/NMI/SBWTDIO and TEST/SBWTCK are wired for , are these for downloading the program into the msp?im also not sure about the PJ.2 pin (FUNCTIONALITY DISABLE).I know its a lot to read but im really short in time about this project and i dont have much time to study everything.so i would be very glad if you could read the code and help me implement the functions into the code.I have started to write the code for my project according to the conditions i have mentioned aboveThis is the code:Code:#include <msp430.h>#include <intrinsics.h>unsigned int timerCount = 0;int main(void) {WDTCTL = WDTPW | WDTHOLD;// Stop watchdog timerP2OUT &= ~(BIT4);//preload 1pps to '0'// set I/O pins directionsP1DIR |=BIT6+BIT7; //set p1.x to 11000000P2DIR |=BIT4;// Set P2.4 to output directionPJDIR |=BIT0+BIT1+BIT3; // set pj.x output 0000 1011P2SEL |= BIT4;//select the option of using TD0.0 in pin 2.4P2IES |= BIT4; // high -> low is selected with IES.x = 1.P2IFG &= ~(BIT4); // To prevent an immediate interrupt, clear the flag for// P1.3 before enabling the interrupt.P2IE |= BIT4; // Enable interrupts for P1.3// Configure XT1 (external oscillator)PJSEL |= BIT4+BIT5;// port select for xt1UCSCTL6 &= ~(XT1OFF);//xt1 is onUCSCTL3 = 0; // FLL REFERENCE CLOCK REFERENCE = XT1// configure TD0.0 to output of 1 pulse per secondTD0CCR0=16000-1; // setting TAR count up value 16000 (12.8MHz / 8 = 1.6MHz , 1.6MHz / 100 = 16000 Hz) when 100 is passed means 1 second has passed as well//TD0CCR1=//DUTY CYCLE OF 50%//TD0CCTL1=CCIE + OUTMOD_7; //enabling interuption + RESET/SET OUTPUT MODETD0CTL0 =MC_2+ID_3+TDSSEL_0+TAIE; //defining timer d TD0.0 (P2.4)__enable_interrupt();for(;;){ // main loop (looping forever)// EXTERNAL / INTERNAL SELECTION BY SW4if ((P2IN & BIT2)==0){ // INTERNAL MODEPJOUT |=BIT3; // sends '1' from pj.3 output to the multiplexer U4 (uses the internal 1pps)//PULSE 1 : DESCRETE ON/OFF AND SWITCH ON/BAD/OFFif ((P2IN & BIT0)==0 || (P1IN & BIT0)==0) { //NORMAL SIGNAL OF 1PPS checks if descrete source is on or 1pps sw pulse 1 is onP1OUT |= BIT6;//ENABLES PULSE BY THE 'AND' GATEPJOUT |= BIT0;//ENABLES TTL TO RS232 CONVERTER (FOR DIFF OUTPUT)#pragma vector = TIMER0_D0_VECTOR__interrupt void TIMER0_D0(void){if (++timerCount > 20) {// checks if the incrementation of timerCount reaches 50 (means 0.5 second has passed)P2OUT ^=BIT4; //generates 1pps out of p2.4timerCount = 0; // resets the timer count}P2IFG &=~(BIT4); // clears the fl}}}else {P1OUT |= ~(BIT6);//DISABLES PULSE BY SENDING A '0' TO THE AND GATE}if ((P1IN & BIT2)==0) {//PULSE 1 BAD SIGNAL ???// CODE HERE FOR BAD SIGNAL PULSE 1//}//PULSE 2 : DESCRETE ON/OFF AND SWITCH ON/BAD/OFFif ((P2IN & BIT1)==0 || (P1IN & BIT0)==0){//NORMAL SIGNAL OF 1PPS checks if descrete source is on or 1pps sw pulse 2 is onP1OUT |= BIT7;//ENABLES PULSE BY THE 'AND' GATEPJOUT |= BIT1;//ENABLES TTL TO RS232 CONVERTER (FOR DIFF OUTPUT)#pragma vector = TIMER0_D0_VECTOR//GENERATES 1PPS EVERY 1s__interrupt void TIMER0_D0 (void){if (++timerCount > 20) {// checks if the incrementation of timerCount reaches 100 (means 1 second has passed)P2OUT ^=BIT4; //generates 1pps out of p2.4timerCount = 0; // resets the timer count}P2IFG &= ~(BIT4); // clears the fl}}else {P1OUT |= ~(BIT7);//DISABLES PULSE BY SENDING A '0' TO THE AND GATE}if ((P1IN & BIT3)==0){//PULSE 1 BAD SIGNAL ???// CODE HERE FOR BAD SIGNAL PULSE 1//}}else {//EXTERNAL MODEPJOUT |= ~(BIT3); //sends '0' from pj.3 output to the multimplexer U4 (uses the external 1pps)P1OUT |= BIT6;// ENABLES PULSE 1P1OUT |= BIT7;//ENABLES PULSE 2PJOUT |= BIT0;//ENABLES RS422 DIFF OUTPUTFOR PULSE 1PJOUT |= BIT1;// ENABLES RS422 DIFF OUTPUT FOR PULSE 2}}}return 0;thanks in advance.