I was briefly considering the 101 for a pulse generator application and did some crude timing tests with the same code running on a 101 (Intel Curie, 32 MHz, core 1.0.5) and an UNO (Atmega 328, 16 MHz).
This is not a thorough or representative exploration, but the results might interest someone else. The procedures are as follows:
a. loop execution with 2 "if" conditionals and ~ 5 variable assignments b. all above plus a bare-bones (2-line) integer pseudorandom sequence generator c. all above plus a floating-point remapping that calls a logarithm, i.e. log()
Results in microseconds:
UNO: a=4, b=11, c=215 101: a=1, b=5, c=368
The surprising thing is the last entry; adjusting for clock rate, the 101 appears 3.4 x less efficient at the log() and associated conversions (other tests I've done confirm it's mostly the log). Neither processor has a FPU, so this sort of calculation should be avoided unless you really need it.
Please forgive the test code, it was just a hasty snip out of my project. I won't have the 101 much longer so I'm posting what I have in case it is useful for anyone else.
#define pulseOutPin 7
#define pulseBarOutPin 6
#define buffySize 512 // for buffer method
unsigned int buffy[buffySize]; // for buffer method
unsigned long tic = 0;
unsigned long toc = 0;
unsigned long toe = 0;
unsigned long standardSeed = 701; // seed for standardRand()
unsigned long tauMean = 600; // microseconds
long delayTime = tauMean; // microseconds [NB: may go negative temporarily !]
unsigned int pulseWidth = 0; // microseconds
int fixedRate = 1 ; // mode switch
int b = 0; // diagnostic, limit serial writes inside loop()
void setup() {
Serial.begin(115200);
while(!Serial);
Serial.println("req time"); Serial.print("\t");
Serial.print("calc time");Serial.print("\t");
Serial.println("elapsed total");
digitalWrite(pulseOutPin, LOW);
digitalWrite(pulseBarOutPin, HIGH);
standardSeed = analogRead(A0); // seed PRNG with open ADC noise
tauMean = max(tauMean, pulseWidth); // floor
for (int k = 0; k < buffySize; k++) { // fill buffer;
buffy[k] = getExpRand(tauMean);
}
} // end of setup()
void loop() {
tic = micros(); // mark time
// digitalWrite(pulseOutPin, HIGH);
// digitalWrite(pulseBarOutPin, LOW);
delayMicroseconds(pulseWidth);
// digitalWrite(pulseOutPin, HIGH);
// digitalWrite(pulseBarOutPin, LOW);
// //
if (fixedRate != 0) { // constant pulse interval
delayTime = tauMean ;
}
else {
if (tauMean > 701) {
// generate-on-the-fly method
float sample = standardRand() * 3.0517578e-05; // uniform long int mapped to float in [0,1)
sample = tauMean * (-log(1.0 - sample)); // uniform to exponential PDF
delayTime = (long) sample; // desired interval to next pulse start
}
else {
// scramble-the-preloaded-buffer method
int j = standardRand() % buffySize; // random pointer in [0 , buffySize)
delayTime = buffy[j]; // desired interval to next pulse start
}
}
// calculate time to next pulse start
toc = micros() - tic; // elapsed time from last pulse start
// delayTime = delayTime - toc; // deduct from desired (RESULT MAY BE NEGATIVE!)
delayTime = max(delayTime, 0); // floor at zero delay
if (delayTime > 999 ) {
delay(delayTime / 1000); //
}
delayMicroseconds(delayTime % 1000) ; // delay remaining microseconds
// diagnostics
toe = micros() - tic;
if (b < 1000) {
b++;
Serial.print(delayTime); Serial.print("\t");
Serial.print(toc); Serial.print("\t"); // microsec
Serial.println(float(toe/1000.), 3); Serial.print("\t"); // calc exec + pulse time
delay(1);
}
} // end of loop()
unsigned int standardRand() {
/*
basic PRNG as supposedly used in C "rand()" function
from Kernighan & Ritchie, 2nd ed., p.43
*/
standardSeed = standardSeed * 1103515245 + 12345;
return (unsigned int)(standardSeed / 65536) % 32768;
} // end of standardRand()
unsigned int getExpRand(unsigned long distMean) {
/*
generate exponentially-distributed random number with specified mean
*/
float samp = standardRand() * 3.0517578e-05; // uniform dist, int mapped to float in [0,1)
samp = distMean * (-log(1.0 - samp)); // exp dist with mean = distMean
return (unsigned int) samp;
} // end of getExpRand()