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Get random seed from noisy ADC conversion at startup.

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This commit is contained in:
David Kopf 2011-08-13 11:31:20 -04:00
parent 40bf585af8
commit f36c97a9a4
3 changed files with 36 additions and 0 deletions
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12
platform/avr-atmega128rfa1/contiki-main.c
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@ -225,6 +225,18 @@ uint16_t p=(uint16_t)&__bss_end;
}
#endif
/* Get a random (or probably different) seed for the 802.15.4 packet sequence number.
* Some layers will ignore duplicates found in a history (e.g. Contikimac)
* causing the initial packets to be ignored after a short-cycle restart.
*/
ADMUX =0x1E; //Select AREF as reference, measure 1.1 volt bandgap reference.
ADCSRA=1<<ADEN; //Enable ADC, not free running, interrupt disabled, fastest clock
ADCSRA|=1<<ADSC; //Start conversion
while (ADCSRA&(1<<ADSC)); //Wait till done
PRINTF("ADC=%d\n",ADC);
random_init(ADC);
ADCSRA=0; //Disable ADC
#define CONF_CALIBRATE_OSCCAL 0
#if CONF_CALIBRATE_OSCCAL
{