Arduino functions for common system identification signals. Currently includes sinusoids and logarithmic chirps.
Clone or unzip this repository into the Arduino libraries folder, or any other folder which is part of the Arduino build path. Normally this is under ~/Documents/Arduino/libraries/.
Sine waves are defined by an amplitude, a frequency (Hz), and an offset. The function prototype is as follows:
void configure_sine(const int amp, const double freq, const int offset = 0);
int sine(unsigned long t);Before calling the sine function, it must be configured using configure_sine. By default, the amplitude, frequency, and offset are all set to zero, so calling the sine wave without configuring it will result in a zero signal.
The following example configures a sinusoid which oscillates between 10 and 20 at a frequency of 8 times per second
int min_value = 10;
int max_value = 20;
int amp = (max_value - min_value)/2;
double freq = 8;
int offset = (max_value + min_value)/2;
configure_sine(amp, freq, offset);The sine function can now be called by
unsigned long t = micros();
int x = sine(t);A chirp signal is a sinusoid whose frequency varies over time, often periodically, with the instantaneous frequency of a sinusoid defined as the derivative of its argument. Many types of chirp signals exist are they defined by form of their instantaneous frequency. This library implements a logarithmic chirp, where the logarithm of the instantaneous frequency is proportional to time.
The implementation in this library includes a logarithmic chirp which sweeps a given frequency band in a given period. This signal is defined by an amplitude, a starting frequency (rad/s), a stopping frequency (rad/s), a period (s), and an offset. The function prototype is as follows
void configure_chirp(const int amp, const double start_freq, const double stop_freq, const int per, const int offset = 0);
int chirp(unsigned long t);Before calling the chirp function, it must be configured using configure_chirp. By default, the amplitude and offset are set to zero, and both frequencies are set to one, and the period is set to 32767.
The following example configures a logarithmic chirp which sweeps from 0.1 rad/s to 10 rad/s in 15 seconds, oscillating between 10 and 20
int min_value = 10;
int max_value = 20;
int amp = (max_value - min_value)/2;
double start_freq = 0.1;
double stop_freq = 10;
int per = 15;
int offset = (max_value + min_value)/2;
configure_chirp(amp, start_freq, stop_freq, per, offset);The chirp function can now be called by
unsigned long t = micros();
int x = chirp(t);