static uint16_t random_seed(void) {
uint16_t seed = 0;
// Enable the radio clock
HWREG(SYS_CTRL_RCGCRFC) = 1;
// Wait until the radio is clocked
while (HWREG(SYS_CTRL_RCGCRFC) != 1);
// Turn the radio on and receive
CC2538_RF_CSP_ISRXON();
// Wait until the RSSI valid signal is high
while (!(HWREG(RFCORE_XREG_RSSISTAT) & RFCORE_XREG_RSSISTAT_RSSI_VALID));
// Sample the radio until the seed is valid (0x0000 and 0x8003 are not valid)
while (seed == 0x0000 || seed == 0x8003) {
for (uint8_t i = 0; i < 16; i++) {
seed |= (HWREG(RFCORE_XREG_RFRND) & RFCORE_XREG_RFRND_IRND);
seed <<= 1;
}
}
// Turn the radio off
CC2538_RF_CSP_ISRFOFF();
return seed;
}
void radio_rxNow() {
//empty buffer before receiving
//CC2538_RF_CSP_ISFLUSHRX();
//enable radio interrupts
enable_radio_interrupts();
CC2538_RF_CSP_ISRXON();
// busy wait until radio really listening
while(!((HWREG(RFCORE_XREG_FSMSTAT1) & RFCORE_XREG_FSMSTAT1_RX_ACTIVE)));
}
/*---------------------------------------------------------------------------*/
static int
on(void)
{
PRINTF("RF: On\n");
if(!(rf_flags & RX_ACTIVE)) {
CC2538_RF_CSP_ISFLUSHRX();
CC2538_RF_CSP_ISRXON();
rf_flags |= RX_ACTIVE;
}
ENERGEST_ON(ENERGEST_TYPE_LISTEN);
return 1;
}
void RfRnd(unsigned char *seed, size_t seedlen)
{
int i = 0, j = 0;
unsigned char s = 0;
int overheated = 0;
#if VERBOSE
int rssi = 0, freqest = 0;
#endif
memset(seed, 0, seedlen);
/* Make sure the RNG is on */
REG(SOC_ADC_ADCCON1) &=
~(SOC_ADC_ADCCON1_RCTRL1 | SOC_ADC_ADCCON1_RCTRL0);
/* Enable clock for the RF Core */
REG(SYS_CTRL_RCGCRFC) = 1;
/* Wait for the clock ungating to take effect */
while (REG(SYS_CTRL_RCGCRFC) != 1);
/* Infinite RX - FRMCTRL0[3:2] = 10
* * This will mess with radio operation - see note above */
REG(RFCORE_XREG_FRMCTRL0) = 0x00000008;
/* Turn RF on */
CC2538_RF_CSP_ISRXON();
#if 0
//This is something evil...
//Turn on PD_OVERRIDE
REG(RFCORE_XREG_PTEST1) = 0x08;
//Turn off LNA and mixer.
REG(RFCORE_XREG_PTEST0) = 0x04;
#endif
/*
* * Wait until "the chip has been in RX long enough for the transients to
* * have died out. A convenient way to do this is to wait for the RSSI-valid
* * signal to go high."
* */
while (!(REG(RFCORE_XREG_RSSISTAT) & RFCORE_XREG_RSSISTAT_RSSI_VALID));
/*
* * Form the seed by concatenating bits from IF_ADC in the RF receive path.
* * Keep sampling until we have read at least 16 bits AND the seed is valid
* *
* * Invalid seeds are 0x0000 and 0x8003 and should not be used.
* */
for (i = 0; i < seedlen; i++) {
//Read 8 bits from RFRND.
for (j = 0; j < 8; j++) {
if (!((REG(RFCORE_XREG_RSSISTAT) & RFCORE_XREG_RSSISTAT_RSSI_VALID)))
{
//RF core is invalidated. Stop reading.
printf("#RFRND invalidated.\n");
overheated = 1;
break;
}
s <<= 1;
s |= (REG(RFCORE_XREG_RFRND) & RFCORE_XREG_RFRND_IRND);
}
if (overheated)
{
break;
}
seed[i] = s;
s = 0;
}
#if VERBOSE
//Read out RSSI and FREQEST.
if(128 <= (rssi = REG(RFCORE_XREG_RSSI)))
rssi -= 256;
if(128 <= (freqest = REG(RFCORE_XREG_FREQEST)))
freqest -= 256;
//Print bits read, RSSI and frequency offset.
printf("#(NBIT,RSSI,FREQEST) %d %d %d\n", i * 8, rssi - 73, (freqest * 7800 - 15000) / 1000 );
#else
printf("#(NBIT) %d\n", i * 8);
#endif
/* RF Off. NETSTACK_RADIO.init() will sort out normal RF operation */
CC2538_RF_CSP_ISRFOFF();
printseed(seed, i);
printf("\n");
return;
}
port_INLINE void radio_on(){
CC2538_RF_CSP_ISFLUSHRX();
CC2538_RF_CSP_ISRXON();
}