![]() Para nuestro ejemplo, de un LED RGB con Arduino no es importante este detalle. If you want to generate a random float in a range, try a next solution. La frecuencia del PWM en Arduino depende del pin donde tomemos la señal (490 o 980 Hz) y se puede variar. See this article for the gritty details about why. For booleans, one usually uses random (0,2) but in my case I need about 250 booleans and calling random every time is slow. Note: the floating point representation of a must be exact or this will never hit your absolute edge case of a (it will get close). 1 I am looking for a way of generating booleans rapidly. I actually prefer this simply because it is clearer what is actually going on (to me, anyway): float x = ((float)rand()/(float)(RAND_MAX)) * a So if I try to call it while multiplexing, the last column appears to flash brighter. ![]() I want to add some random behavior, but the random () function takes as much as 130 µS per call. ![]() Which can be rewritten as: a * (N/RAND_MAX)Ĭonsidering N/RAND_MAX is always a floating point value between 0.0 and 1.0, this will generate a value between 0.0 and a.Īlternatively, you can use the following, which effectively does the breakdown I showed above. My LED multiplexing code operates at a rate of about 20-30 µS per column. Some rounding is actually necessary: if you want to generate uniform float value over 0. The above equation (removing the casts for clarity) becomes: N/(RAND_MAX/a)īut division by a fraction is the equivalent to multiplying by said fraction's reciprocal, so this is equivalent to: N * (a/RAND_MAX) GlennMaynard: If you were dividing by (RANDMAX+1ULL) (presumably a power of 2), youd just be scaling the FP exponent. To understand how this works consider the following. There are a lot of articles about this matter, but since we have the Serial plotter I would like to add this one. Try: float x = (float)rand()/(float)(RAND_MAX/a) ![]()
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