Random Numbers

randomSeed()

randomSeed

randomSeed(newSeed);

Parameters:

  • newSeed - the new random seed

The pseudorandom numbers produced by the firmware are derived from a single value - the random seed. The value of this seed fully determines the sequence of random numbers produced by successive calls to random(). Using the same seed on two separate runs will produce the same sequence of random numbers, and in contrast, using different seeds will produce a different sequence of random numbers.

On startup, the default random seed is set by the system to 1. Unless the seed is modified, the same sequence of random numbers would be produced each time the system starts.

Fortunately, when the device connects to the cloud, it receives a very randomized seed value, which is used as the random seed. So you can be sure the random numbers produced will be different each time your program is run.

Disable random seed from the cloud

When the device receives a new random seed from the cloud, it's passed to this function:

void random_seed_from_cloud(unsigned int seed);

The system implementation of this function calls randomSeed() to set the new seed value. If you don't wish to use random seed values from the cloud, you can take control of the random seeds set by adding this code to your app:

void random_seed_from_cloud(unsigned int seed) {
   // don't do anything with this. Continue with existing seed.
}

In the example, the seed is simply ignored, so the system will continue using whatever seed was previously set. In this case, the random seed will not be set from the cloud, and setting the seed is left to up you.