Diff: main.cpp.orig

Revision:

16:24e992616cf6

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp.orig	Wed Sep 24 08:31:30 2014 +0000
@@ -0,0 +1,90 @@
+#include "mbed.h"
+#include "MODSERIAL.h"
+
+//Define objects
+AnalogIn    emg0(PTB1); //Analog input
+PwmOut      red(LED_RED); //PWM output
+Ticker log_timer;
+MODSERIAL pc(USBTX,USBRX);
+
+typedef struct second_order_constants
+{
+    float b[3];
+    float a[3];
+} second_order_constants_t;
+
+typedef struct second_order_values
+{
+    float x_1,x_2;
+    float y_1,y_2;
+} second_order_values_t;
+
+//constants
+second_order_constants_t highpass= {{0.97803048, -1.95606096,  0.97803048},{1, -1.95557824,  0.95654368}};
+//type for values
+second_order_values_t highpass_values;
+
+float second_order(float x, second_order_constants_t constants, second_order_values_t &values);
+
+
+/** Looper function
+* functions used for Ticker and Timeout should be of type void <name>(void)
+* i.e. no input arguments, no output arguments.
+* if you want to change a variable that you use in other places (for example in main)
+* you will have to make that variable global in order to be able to reach it both from
+* the function called at interrupt time, and in the main function.
+* To make a variable global, define it under the includes.
+* variables that are changed in the interrupt routine (written to) should be made
+* 'volatile' to let the compiler know that those values may change outside the current context.
+* i.e.: "volatile uint16_t emg_value;" instead of "uint16_t emg_value"
+* in the example below, the variable is not re-used in the main function, and is thus declared
+* local in the looper function only.
+**/
+void looper()
+{
+    /*variable to store value in*/    
+    uint16_t emg_value;
+    float filtered_emg;
+    /*put raw emg value both in red and in emg_value*/
+    red.write(emg0.read());      // read float value (0..1 = 0..3.3V)
+    emg_value = emg0.read_u16(); // read direct ADC result, converted to 16 bit integer (0..2^16 = 0..65536 = 0..3.3V)
+    filtered_emg = second_order((float)emg_value,highpass, highpass_values);
+    /*send value to PC. Line below is used to prevent buffer overrun */
+    if(pc.rxBufferGetSize(0)-pc.rxBufferGetCount() > 30)
+        pc.printf("%u\t%f\n",emg_value, filtered_emg);
+    /**When not using the LED, the above could also have been done this way:
+    * pc.printf("%u\n", emg0.read_u16());
+    */
+}
+
+int main()
+{
+    /*setup baudrate. Choose the same in your program on PC side*/
+    pc.baud(115200);
+    /*set the period for the PWM to the red LED*/
+    red.period_ms(2);
+    /**Here you attach the 'void looper(void)' function to the Ticker object
+    * The looper() function will be called every 0.01 seconds.
+    * Please mind that the parentheses after looper are omitted when using attach.
+    */
+    log_timer.attach(looper, 0.01);
+    while(1) //Loop
+    {
+      /*Empty!*/
+      /*Everything is handled by the interrupt routine now!*/
+    }
+}
+
+float second_order(float x, second_order_constants_t constants, second_order_values_t &values)
+{
+    float y = 0;
+    float b_terms, a_terms;
+    b_terms = (constants.b[0]*x) + (constants.b[1]*values.x_1) + (constants.b[2]*values.x_2);
+    a_terms = (constants.a[1]*values.y_1) + (constants.a[2]*values.y_2);
+    y=(1./constants.a[0])* (b_terms-a_terms);
+    values.x_2 = values.x_1;
+    values.x_1 = x;
+    values.y_2 = values.y_1;
+    values.y_1 = y;
+    return y;
+}
\ No newline at end of file