// Set the channel fast and discard the first wrong readings
void my_set_channel(int ch)
{
int k, temp;
SPI_SETCHANNEL_SUPERFAST(357+((ch-11)*5)); // Approx. 292 us
// Discard first 16 bad readings
CC2420_SPI_ENABLE();
for (k=0; k<=16; k++) {
MY_FASTSPI_GETRSSI(temp);
}
clock_delay(1);
CC2420_SPI_DISABLE();
}
PROCESS_THREAD(scanning, ev, data)
{
PROCESS_BEGIN();
// Initial operations
leds_off(LEDS_ALL);
watchdog_stop();
// Avoiding wrong RSSI readings
unsigned temp;
CC2420_READ_REG(CC2420_AGCTST1, temp);
CC2420_WRITE_REG(CC2420_AGCTST1, (temp + (1 << 8) + (1 << 13)));
// Selecting the channel
SPI_SETCHANNEL_SUPERFAST(357+((CHANNEL-11)*5));
// Avoiding the initial wrong readings by discarding the wrong readings
CC2420_SPI_ENABLE();
unsigned long k=0;
for (k=0; k<=15; k++) {MY_FASTSPI_GETRSSI(temp);}
CC2420_SPI_DISABLE();
static struct etimer et;
while(1){
#if VERBOSE
printf("#START (dBm: occurrencies)\n");
#endif
// Resetting everything
for(k=0;k<BUFFER_SIZE;k++){
buffer0[k] = 0;
}
dint(); // Disable interrupts
boost_cpu(); // Temporarily boost CPU speed
CC2420_SPI_ENABLE(); // Enable SPI
// Actual scanning
static signed char rssi;
for(k=0; k<MAX_VALUE; k++){
MY_FASTSPI_GETRSSI(rssi);
buffer0[rssi+55]++;
}
CC2420_SPI_DISABLE(); // Disable SPI
restore_cpu(); // Restore CPU speed
eint(); // Re-enable interrupts
// Printing the stored values in compressed form
unsigned long sum_cca = 0;
unsigned long max = 0, max_value = 0;
for(temp=0; temp<BUFFER_SIZE; temp++) {
sum_cca += (temp * buffer0[temp]);
if(buffer0[temp] > max){
max = buffer0[temp];
max_value = temp;
}
}
// Printing the results of the CCA
float f_cca = (((float) sum_cca*1.0000) / MAX_VALUE)-100.0000;
#if VERBOSE
printf("Average noise: %ld.%04u\nStatistic Mode noise: %ld\n", (long) f_cca, (unsigned)((f_cca-floor(f_cca))*10000), max_value-100);
#else
printf("%ld.%04u\n", (long) f_cca, (unsigned)((f_cca-floor(f_cca))*10000));
#endif
#if VERBOSE
printf("#END\n");
#endif
// Waiting for timer
etimer_set(&et, PERIOD_TIME);
PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));
}
PROCESS_WAIT_EVENT();
PROCESS_END();
}
PROCESS_THREAD(scanning, ev, data)
{
PROCESS_BEGIN();
// Initial operations
leds_off(LEDS_ALL);
watchdog_stop();
// Avoiding wrong RSSI readings
unsigned temp;
CC2420_READ_REG(CC2420_AGCTST1, temp);
CC2420_WRITE_REG(CC2420_AGCTST1, (temp + (1 << 8) + (1 << 13)));
// Selecting the channel
SPI_SETCHANNEL_SUPERFAST(357+((CHANNEL-11)*5));
// Avoiding the initial wrong readings by discarding the wrong readings
CC2420_SPI_ENABLE();
int k=0;
for (k=0; k<=15; k++) {
MY_FASTSPI_GETRSSI(temp);
}
CC2420_SPI_DISABLE();
static struct etimer et;
while(1) {
// Resetting everything
for(k=0; k<(BUFFER_SIZE/2); k++) {
buffer1[k] = 0;
buffer0[k] = 0;
}
printf("#START [dBm: occurrencies]\n");
dint(); // Disable interrupts
boost_cpu(); // Temporarily boost CPU speed
CC2420_SPI_ENABLE(); // Enable SPI
// Actual scanning
static signed char rssi;
int current = 0;
int previous = 0;
int cnt = 1;
for(k=0; k<(BUFFER_SIZE/2);) {
// Sample the RSSI fast
MY_FASTSPI_GETRSSI(rssi);
current = rssi + 55;
if((current == previous)&&(cnt<255)) {
cnt++;
}
else {
buffer0[k] = previous;
buffer1[k++] = cnt;
cnt = 1;
previous = current;
}
}
CC2420_SPI_DISABLE(); // Disable SPI
restore_cpu(); // Restore CPU speed
eint(); // Re-enable interrupts
// Printing the stored values in compressed form
for(temp=0; temp<(BUFFER_SIZE/2); temp++) {
printf("%d: %d\n",buffer0[temp] - 100, buffer1[temp]);
clock_delay(30000);
}
printf("#END\n");
// Waiting for timer
etimer_set(&et, PERIOD_TIME);
PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));
}
PROCESS_WAIT_EVENT();
PROCESS_END();
}