Get random seed from noisy ADC conversion at startup.

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

View file

@ -225,6 +225,18 @@ uint16_t p=(uint16_t)&__bss_end;
} }
#endif #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 #define CONF_CALIBRATE_OSCCAL 0
#if CONF_CALIBRATE_OSCCAL #if CONF_CALIBRATE_OSCCAL
{ {

View file

@ -208,6 +208,18 @@ uint16_t p=(uint16_t)&__bss_end;
} }
#endif #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
PRINTFD("ADC=%d\n",ADC);
random_init(ADC);
ADCSRA=0; //Disable ADC
#define CONF_CALIBRATE_OSCCAL 0 #define CONF_CALIBRATE_OSCCAL 0
#if CONF_CALIBRATE_OSCCAL #if CONF_CALIBRATE_OSCCAL
{ {

View file

@ -423,6 +423,18 @@ uint16_t p=(uint16_t)&__bss_end;
Leds_init(); Leds_init();
Led1_on(); Led1_on();
/* 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
PRINTD("ADC=%d\n",ADC);
random_init(ADC);
ADCSRA=0; //Disable ADC
#if USB_CONF_RS232 #if USB_CONF_RS232
/* Use rs232 port for serial out (tx, rx, gnd are the three pads behind jackdaw leds */ /* Use rs232 port for serial out (tx, rx, gnd are the three pads behind jackdaw leds */
rs232_init(RS232_PORT_0, USART_BAUD_57600,USART_PARITY_NONE | USART_STOP_BITS_1 | USART_DATA_BITS_8); rs232_init(RS232_PORT_0, USART_BAUD_57600,USART_PARITY_NONE | USART_STOP_BITS_1 | USART_DATA_BITS_8);