Revision 0:c85b764527f4, committed 2015-10-26

Comitter:

roosbulthuis

Date:

Mon Oct 26 14:26:22 2015 +0000

Child:

1:f32f8eac8af1

Commit message:

Plotting EMG signal in hidscope works, but plotting a test value or filtered signal in second channel does not work. Test value outside/inside function does not matter.

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HIDScope.lib	Mon Oct 26 14:26:22 2015 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/tomlankhorst/code/HIDScope/#5020a2c0934b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Oct 26 14:26:22 2015 +0000
@@ -0,0 +1,153 @@
+#include "mbed.h"
+//#include "read_filter_emg.h"
+//included for fabs() function
+#include <math.h>
+#include "HIDScope.h"
+
+Ticker sample_timer;
+HIDScope scope(1);
+
+AnalogIn analog_emg_left(A0);
+AnalogIn analog_emg_right(A1);
+double input_left = 0;
+double input_right = 0;
+
+double v1_left=0;
+double v2_left=0;
+double v1_right=0;
+double v2_right=0;
+
+double filter_left;
+double filter_right;
+
+//general biquad filter that can be called in all the filter functions
+double biquad(double u, double &v1, double &v2, const double a1,
+              const double a2, const double b0, const double b1, const double b2)
+{
+    double v = u * a1*v1 * a2*v2;
+    double y = b0*v + b1*v1 + b2*v2;
+    //values of v2 and v1 are updated, as they are passed by reference
+    //they update globally
+    v2 = v1;
+    v1 = v;
+    return y;
+}
+
+//Specifying filter coefficients highpass
+
+/* high pass filter consists of three cascaded biquads
+ blow coefficients for those three biquads */
+//first high pass biquad
+const double highp1_a1 = -0.67538034389;
+const double highp1_a2 = 0.12769255668;
+const double highp1_b0 = 1.00000000000;
+const double highp1_b1 = -2.00000000000;
+const double highp1_b2 = 1.00000000000;
+
+//second high pass biquad
+const double highp2_a1 = -0.76475499450;
+const double highp2_a2 = 0.27692273367;
+const double highp2_b0 = 1.00000000000;
+const double highp2_b1 = -2.00000000000;
+const double highp2_b2 = 1.00000000000;
+
+//third high pass biquad
+const double highp3_a1 = -0.99216561242;
+const double highp3_a2 = 0.65663360837;
+const double highp3_b0 = 1.00000000000;
+const double highp3_b1 = -2.00000000000;
+const double highp3_b2 = 1.00000000000;
+
+//Specifying filter coefficients lowpass
+
+/* lowpass filter consists of three cascaded biquads
+below the coefficients for those three biquads */
+//first high pass biquad
+const double lowp1_a1 = -1.05207469728;
+const double lowp1_a2 = 0.28586907478;
+const double lowp1_b0 = 1.00000000000;
+const double lowp1_b1 = 2.00000000000;
+const double lowp1_b2 = 1.00000000000;
+
+//second high pass biquad
+const double lowp2_a1 = -1.16338171052;
+const double lowp2_a2 = 0.42191097989;
+const double lowp2_b0 = 1.00000000000;
+const double lowp2_b1 = 2.00000000000;
+const double lowp2_b2 = 1.00000000000;
+
+//third high pass biquad
+const double lowp3_a1 = -1.42439823874;
+const double lowp3_a2 = 0.74093118112;
+const double lowp3_b0 = 1.00000000000;
+const double lowp3_b1 = 2.00000000000;
+const double lowp3_b2 = 1.00000000000;
+
+//input to each filter is output of the filter before(excl. first which uses input_sample)
+/* NOT SURE IF PASSING V1 AND V2 IS CORRECT,
+WILL IT UPDATE IN THE MEMORY POSITION SO THAT
+V1 IS CHANGED GLOBALLY */
+
+//highpass
+
+double highpass_filter(double input, double &v1, double &v2)
+{
+    double y1 = biquad(input, v1, v2, highp1_a1, highp1_a2, highp1_b0, highp1_b1, highp1_b2);
+    double y2 = biquad(y1, v1, v2, highp2_a1, highp2_a2, highp2_b0, highp2_b1, highp2_b2);
+    double y3 = biquad(y2, v1, v2, highp3_a1, highp3_a2, highp3_b0, highp3_b1, highp3_b2);
+
+    return y3;
+}
+
+
+//rectifier
+double rectify(double y3)
+{
+    y3 = fabs(y3);
+    return y3;
+}
+
+//lowpass
+
+double lowpass_filter(double y3, double &v1, double &v2)
+{
+    double y4 = biquad(y3, v1, v2, lowp1_a1, lowp1_a2, lowp1_b0, lowp1_b1, lowp1_b2);
+    double y5 = biquad(y4, v1, v2, lowp2_a1, lowp2_a2, lowp2_b0, lowp2_b1, lowp2_b2);
+    double filtered_signal = biquad(y5, v1, v2, lowp3_a1, lowp3_a2, lowp3_b0, lowp3_b1, lowp3_b2);
+
+    return filtered_signal;
+}
+
+double filter(double input, double &v1, double &v2)
+{
+    /* function passes the input through the three filters
+    returns the final output value as filtered sample
+    this is used in check_state() function to determine state of system
+    */
+    double y1 = highpass_filter(input, v1, v2);
+    double y2 = rectify(y1);
+    double filtered_signal = lowpass_filter(y2, v1, v2);
+
+    return filtered_signal;
+}
+
+double test=1;
+
+void sample()
+{
+    input_left = analog_emg_left.read();
+    input_right = analog_emg_right.read();
+    filter_left = filter(input_left, v1_left, v2_left);
+    filter_right = filter(input_right, v1_right, v2_right);
+    
+    scope.set(0, input_left);
+    scope.set(1, test);
+    scope.send();
+}
+
+
+int main()
+{
+    sample_timer.attach(&sample, 0.002);
+    while(1){}
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Mon Oct 26 14:26:22 2015 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/34e6b704fe68
\ No newline at end of file