Quick Entropy library raw data test

gistfile1.txt

// A very quick entropy test.  Run on Teensy 3.x or Teensy LC.
// https://twitter.com/DavidInOregon/status/937304504210423808

volatile uint8_t val=0;
volatile bool newval=false;

void setup() {
  SIM_SCGC5 |= SIM_SCGC5_LPTIMER;
  LPTMR0_CSR = 0b10000100;
  LPTMR0_PSR = 0b00000101;  // PCS=01 : 1 kHz clock
  LPTMR0_CMR = 0x0006;      // smaller number = faster random numbers...
  LPTMR0_CSR = 0b01000101;
  NVIC_ENABLE_IRQ(IRQ_LPTMR);
}

void lptmr_isr(void)
{
  LPTMR0_CSR = 0b10000100;
  LPTMR0_CSR = 0b01000101;
  val = SYST_CVR;
  newval = true;
}

void loop() {
  if (newval) {
    newval = false;
    Serial.println(val);
  }
}