From f36c97a9a4bec7f7b9981433b406754d2af78597 Mon Sep 17 00:00:00 2001
From: David Kopf <dak664@embarqmail.com>
Date: Sat, 13 Aug 2011 11:31:20 -0400
Subject: [PATCH] Get random seed from noisy ADC conversion at startup.

---
 platform/avr-atmega128rfa1/contiki-main.c  | 12 ++++++++++++
 platform/avr-raven/contiki-raven-main.c    | 12 ++++++++++++
 platform/avr-ravenusb/contiki-raven-main.c | 12 ++++++++++++
 3 files changed, 36 insertions(+)

diff --git a/platform/avr-atmega128rfa1/contiki-main.c b/platform/avr-atmega128rfa1/contiki-main.c
index 41fccfebe..93bbe4496 100644
--- a/platform/avr-atmega128rfa1/contiki-main.c
+++ b/platform/avr-atmega128rfa1/contiki-main.c
@@ -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
 {
diff --git a/platform/avr-raven/contiki-raven-main.c b/platform/avr-raven/contiki-raven-main.c
index 1758274ce..ff0865934 100644
--- a/platform/avr-raven/contiki-raven-main.c
+++ b/platform/avr-raven/contiki-raven-main.c
@@ -207,6 +207,18 @@ uint16_t p=(uint16_t)&__bss_end;
     } while (p<SP-10); //don't overwrite our own stack
 }
 #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
 #if CONF_CALIBRATE_OSCCAL
diff --git a/platform/avr-ravenusb/contiki-raven-main.c b/platform/avr-ravenusb/contiki-raven-main.c
index 7abbd7d4b..edd3b7b71 100644
--- a/platform/avr-ravenusb/contiki-raven-main.c
+++ b/platform/avr-ravenusb/contiki-raven-main.c
@@ -422,6 +422,18 @@ uint16_t p=(uint16_t)&__bss_end;
   /* Led0 Blue Led1 Red Led2 Green Led3 Yellow */
   Leds_init();
   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
   /* Use rs232 port for serial out (tx, rx, gnd are the three pads behind jackdaw leds */