Diff: main.cpp

Revision:

0:ee3bdb31da2f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat Jan 29 12:35:32 2011 +0000
@@ -0,0 +1,100 @@
+#include "mbed.h"
+
+LocalFileSystem local("local");
+Serial pc(USBTX, USBRX);
+Ticker timer; //interrupt to generate sine wave
+DigitalOut low(LED1);
+DigitalOut oc(LED2);
+DigitalOut high(LED3);
+AnalogIn level(p20);
+AnalogOut sine_wave(p18);
+PwmOut wave(p26);
+
+float pulse_freq;
+float pulse_period;
+float pulse_width;
+float sine_freq;
+float sine_period;
+float sine_amp;
+float sine_vals[19], *sp, *last; //setup array for sine values, a pointer to access the array and one for the end of the array
+void setup();
+void sine();
+void sine_table();
+
+int main() {
+    float a;
+        
+    FILE *fp=fopen("/local/setup.ini", "r");
+    if(!fp) { 
+        pulse_period=1; //default values if no .ini file
+        pulse_width=0.5;
+        sine_freq=1000;
+        sine_amp=3.3; // peak to peak sine amplitude in V
+        }
+    else {
+        fscanf(fp,"%f %f %f %f",&pulse_period, &pulse_width, &sine_freq, &sine_amp); //read values from .ini file
+        fclose(fp);
+        }
+    wave.period(pulse_period);
+    wave=pulse_width;
+    sine_table(); //load sine values into table and start interrupt
+    
+    while(1) { //main loop
+    a=level;
+    low=(a<0.24); // light low led if voltage less then 0.8V
+    high=(a>0.61); // light high led if voltage greater than 2V
+    oc=(a>=0.24 && a<=0.61); //light oc LED if open circuit or indeterminate level
+    if (pc.readable()) setup(); //if PC keyboard pressed setup waveforms via pc 
+    }
+ }
+
+void setup() { //function to get waveform values from pc
+    printf("\f\n Pulse Frequency (0.1-1000000Hz):- \n");
+    scanf("%f",&pulse_freq);
+    if (pulse_freq>1000000) pulse_freq=1000000;
+    if (pulse_freq<0.1) pulse_freq=0.1;
+    pulse_period=1/pulse_freq;
+    printf("\n Pulse Width (0.1-0.9):- \n");
+    scanf("%f",&pulse_width);
+    if (pulse_width>0.9) pulse_width=0.9;
+    if (pulse_width<0.1) pulse_width=0.1;
+    printf("\n Sine Frequency (0.1-1000Hz):- \n");
+    scanf("%f",&sine_freq);
+    if (sine_freq>1000) sine_freq=1000;
+    if (sine_freq<0.1) sine_freq=0.1;
+    printf("\n Sine Amplitude (0-3.3V p/p):- \n");
+    scanf("%f",&sine_amp);
+    if (sine_amp>3.3) sine_amp=3.3;
+    if (sine_amp<0) sine_amp=0;
+    printf("\n\n Pulse Frequency %f Hz \n Pulse Width %f \n",pulse_freq, pulse_width);
+    printf("\n Sine Frequency %f Hz \n Sine Amplitude %f V \n",sine_freq, sine_amp); 
+    FILE *fp=fopen("/local/setup.ini","w"); // save values on flash drive
+    fprintf(fp,"%f %f %f %f",pulse_period,pulse_width,sine_freq,sine_amp);
+    fclose(fp);
+    wave.period(pulse_period); //start PWM output
+    wave=pulse_width;
+    sine_table(); // load new values into sine table and start interrupt
+}
+
+void sine_table() { // function to load sine values into array and start interrupt
+    float *p, i;
+    
+    sine_amp=sine_amp/3.3; //convert from p/p voltage to percentage
+    p=sine_vals; //set p to point to beginning of array
+    sp=p; //set sp also
+    for (i=0;i<3;i+=0.15707965) {
+        *p=sine_amp*sin(i);
+        p++;
+        }
+    last=p-1; //last element in array
+
+    sine_period=(1000000/sine_freq)/19; // period between calling sine routine
+    timer.attach_us(&sine,sine_period); // start the interrupt
+}
+    
+void sine() { // function to output sine wave to analogue output
+
+    if (sp>last) sp=sine_vals; //if at end of array reset sp back to beginning
+    sine_wave.write(*sp);
+    sp++;
+}