Measure EMG, publish on HID Scope
Dependencies: HIDScope mbed mbed-dsp
Fork of EMG by
Diff: main.cpp.orig
- Revision:
- 16:24e992616cf6
diff -r d3a849ab3697 -r 24e992616cf6 main.cpp.orig --- /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