Measure EMG, publish on HID Scope
Dependencies: HIDScope mbed mbed-dsp
Fork of EMG by
main.cpp.orig
- Committer:
- vsluiter
- Date:
- 2014-09-29
- Revision:
- 20:f7d281e3112b
- Parent:
- 16:24e992616cf6
File content as of revision 20:f7d281e3112b:
#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; }