CPS-Lab
Analog Filters and Oscilloscope
Dependencies: mbed
Revision 0:0981765e0a06, committed 2018-03-03
- Comitter:
- kmhatre
- Date:
- Sat Mar 03 02:53:19 2018 +0000
- Commit message:
- Analog Filters
Changed in this revision
diff -r 000000000000 -r 0981765e0a06 main.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Sat Mar 03 02:53:19 2018 +0000
@@ -0,0 +1,201 @@
+
+/*
+ * ENGR E 210 - CYBER PHYSICAL SYSTEMS (DIGITAL SYSTEMS)
+ * LAB 3 - ANALOG FILTERS AND OSCILLOSCOPE
+ * CODE BY KRISH HEMANT MHATRE AND ETHAN ZHANG
+ */
+#include "mbed.h"
+#include <string.h>
+
+#if !DEVICE_ANALOGOUT
+#error You cannot use this example as the AnalogOut is not supported on this device.
+#else
+AnalogOut my_output(PA_4);
+#endif
+
+#define PI (3.141592653589793238462)
+#define AMPLITUDE (1.0) // x * 3.3V
+#define PHASE (PI * 1) // 2*pi is one period
+#define RANGE (0x7FFF)
+#define OFFSET (0x7FFF)
+
+// Configuration for sinewave output
+#define BUFFER_SIZE (360)
+uint16_t buffer[BUFFER_SIZE];
+
+Serial pc(USBTX, USBRX);
+DigitalOut led1(LED1);
+DigitalIn button(PC_13);
+
+void Led(int a)
+{
+ led1 = a;
+}
+
+void Blink(int n)
+{
+ int i = 0;
+ for(i=0; i<n; i++)
+ {
+ led1 = 1;
+ wait(0.5);
+ led1= 0;
+ wait(0.5);
+ }
+}
+
+
+void Button()
+{
+ if(button.read() == 1)
+ {
+ pc.printf("RELEASED\n\r");
+ }
+ else
+ {
+ pc.printf("PRESSED\n\r");
+ }
+}
+
+void calculate_sinewave(float amp){
+ for (int i = 0; i < BUFFER_SIZE; i++) {
+ double rads = (PI * i)/180.0; // Convert degree in radian
+ buffer[i] = (uint16_t)(amp * (RANGE * (cos(rads + PHASE))) + OFFSET);
+ }
+}
+
+int main()
+{
+ pc.printf("Nucleo is running\n\r");
+ pc.printf("cps%\n\r");
+ int size = 32;
+ char str[size];
+ int i = 0;
+ while(1)
+ {
+ str[i] = pc.getc();
+ pc.putc(str[i]);
+
+ if (i >= size)
+ {
+ pc.printf("OVER BUFFER\n\r");
+ i = 0;
+ for(int j = 0; j < size; j++)
+ {
+ str[j] = 0;
+ }
+ pc.printf("cps%\n\r");
+ }
+ if(str[i] == 13)
+ {
+ pc.printf("\n\rOK\n\r");
+ str[i] = '\0';
+ pc.printf("Command Recieved: %s\n\r", str);
+ char s[5];
+ sscanf(str, "%s", s);
+ if(strcmp(str, "BUTTON") == 0)
+ {
+ Button();
+ pc.printf("Button checked.\n\r");
+ }
+ else if(strcmp("LED ON", str) == 0)
+ {
+ Led(1);
+ pc.printf("LED is on\n\r");
+ }
+ else if(strcmp("LED OFF", str) == 0)
+ {
+ Led(0);
+ pc.printf("LED is off\n\r");
+ }
+ else if(strcmp(s, "BLINK") == 0)
+ {
+ pc.printf("Reading a blink\n\r");
+ char *a = strtok(str, " ");
+ a = strtok(NULL, " ");
+ pc.printf("Start blink\n\r");
+ int n;
+ sscanf(a, " %d", &n);
+ if(n>=1 && n<=10)
+ {
+ Blink(n);
+ pc.printf("Blink complete\n\r");
+ }
+ else
+ {
+ pc.printf("ERROR: Blink cycle should be between 1 and 10\n\r");
+ }
+ }
+ else if(strncmp(str, "DC", 2) == 0)
+ {
+ pc.printf("Reading DC\n\r");
+ char *s1 = strtok(str, " ");
+ s1 = strtok(NULL, " ");
+ float volt;
+ sscanf(s1, " %f", &volt);
+
+ if((volt < (float)0.5) || (volt > (float)3.0))
+ {
+ pc.printf("Voltage out of range\n\r");
+ }
+ else
+ {
+ float adjust = 19720;
+
+ pc.printf("Voltage is %f\n\r", volt);
+ my_output.write_u16(volt*adjust);
+ pc.printf("Voltage changed\n\r");
+ }
+ }
+ else if(strncmp(str, "SINE", 4) == 0)
+ {
+ float x, amp, freq;
+ char tmp[5];
+
+ sscanf(str, "%s %f %f\n", tmp, &, &freq);
+ pc.printf("Reading data\n\r");
+ if((amp < (float)0.5) || (amp > (float)3.0) || (freq < (float)100) || (freq > (float)500))
+ {
+ pc.printf("Data out of range\n\r");
+ }
+ else
+ {
+ pc.printf("Generating sine wave of amplitude %fV and frequency %fHz\n\r", amp, freq);
+ x = (float)((float)amp/(float)3.3); //3.3V is the given voltage
+ calculate_sinewave(x);
+ while(1)
+ {
+ for (int i = 0; i < BUFFER_SIZE; i++)
+ {
+ my_output.write_u16(buffer[i]);
+ float delay;
+ if(freq <= 200)
+ {
+ delay = (float)((float)((float)4000-(float)((float)5*freq))/(float)(freq*(float)(PI/2)));
+ }
+ else
+ {
+ delay = (float)((float)((float)5000-(float)((float)12*(float)freq))/(float)(freq));
+ }
+ delay = ((float)(delay/1000000)); //converting microseconds to seconds
+ wait(delay);
+ }
+ }
+ }
+ }
+ else
+ {
+ pc.printf("ERR\n\r");
+ }
+ i = 0;
+ for(int j = 0; j < size; j++)
+ {
+ str[j] = '\0';
+ }
+ pc.printf("cps%\n\r");
+ }
+ i++;
+ }
+}
+
+
diff -r 000000000000 -r 0981765e0a06 mbed.bld --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Sat Mar 03 02:53:19 2018 +0000 @@ -0,0 +1,1 @@ +https://os.mbed.com/users/mbed_official/code/mbed/builds/7130f322cb7e \ No newline at end of file
diff -r 000000000000 -r 0981765e0a06 report.txt --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/report.txt Sat Mar 03 02:53:19 2018 +0000 @@ -0,0 +1,37 @@ +Filter Ideal Analysis +Frequency(Hz) V out +100 0.893 +110 0.875 +120 0.856 +130 0.837 +140 0.818 +150 0.798 +160 0.779 +170 0.76 +180 0.741 +190 0.723 +200 0.7 + + +Filter Measurements +Frequency(Hz) V out +100 0.895 +110 0.88 +120 0.858 +130 0.84 +140 0.82 +150 0.8 +160 0.776 +170 0.762 +180 0.746 +190 0.719 +200 0.704 + +R = 800ohms +C = 1uF +f(cutoff) = 200Hz + +The major problem in this assignment was to figure out the frequency part. The calculation of the relationship between frequency +and delay took majority of the time. It was easy to make the analysis on paper, but while working it out on oscilloscope was very +time consuming as it was completely based on trial and error. +Finally The code worked properly except that for higher values of frequency the standard deviatoion is pretty high.