Repeat Pick Random not random adafruit curcuit playground blocks

[asaawens]

https://makecode.com/_CYU1mq4atcRV

I loaded this on 2 Adafruit Curcuit Playgound devices. They synch start, but despite being told to pick a random number of repeat times, both controllers repeat the loops the same amount of times. So the sequence progresses through the music in the same way. Why would the random seed be the same each time it is run?

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[riknoll]

@mmoskal FYI

[mmoskal]

feel free to ping me when you're doing next release

[smagoun]

I ran into this too. I believe the random seed is hardcoded for the SAMD21 boards (like CPX), and this is an issue upstream rather than in pxt-adafruit.

For example a simple program that prints 20 random numbers in the range 0-10:

input.buttonB.onEvent(ButtonEvent.Click, function () {
    for (let i = 0; i < 20; i++) {
        console.log(Math.randomRange(0, 10))
    }
})

...will always start: 0,6,0,6,0,0,1,9,4,2,10,3,10,3,8,10,10,5,3,2

See the initRandomSeed() implementation here; the seed is fixed: https://github.com/microsoft/pxt-common-packages/blob/master/libs/core---samd/platform.cpp#L121

The core platform has an implementation of initRandomSeed() that takes input from the temperature + light sensors, which should make it more random; maybe that could be ported to core---samd? https://github.com/microsoft/pxt-common-packages/blob/master/libs/core/platform.cpp#L8

As a workaround I made a function that uses the light + sound sensors to add entropy:

let rand = 0
function getRandom(min: number, max: number): number {
    rand = Math.randomRange(0, 255)
    rand = rand + input.soundLevel()
    rand = rand + input.lightLevel()
    rand = rand / 3
    rand = Math.round((rand % (max - min)) + min)
    return rand
}