random_from_adc.c

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#include <cc2511_types.h>
#include <cc2511_map.h>
#include <random.h>

static uint8 adcReadTemp(void)
{
    ADCIF = 0;               // Clear the flag.
    ADCCON3 = 0b10001110;    // Read the temperature sensor using VDD as a reference, with only 7 bits of resolution.
    while(!ADCIF){};         // Wait for the reading to finish.
    return ADCL;
}

void randomSeedFromAdc(void)
{
    randomSeed(adcReadTemp(), adcReadTemp());
}

// The function below was commented out because it was not being used and might
// not be needed:
/* Adds another seed to the state of the random number generator.
 * If you do this regularly, it will help guarantee that no two Wixels have the
 * same random number stream (at least not for long).
 */
/*
void randomRefreshFromAdc()
{
    adcReadTemp();

    while(ADCCON1 & 0x0C);                   // Wait for the last random number to finish.
    RNDL = RNDH ^ ADCL;                      // Add the seed, but don't throw away the randomness in RNDH.
    ADCCON1 = (ADCCON1 & ~0x0C) | 0x07;      // Start generating the next random number.
}*/

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