/**************************************************************************************************
* @fn MRFI_Rssi
*
* @brief Returns "live" RSSI value
*
* @param none
*
* @return RSSI value in units of dBm.
**************************************************************************************************
*/
int8_t MRFI_Rssi(void)
{
/* Radio must be in RX state to measure rssi. */
MRFI_ASSERT( mrfiRadioState == MRFI_RADIO_STATE_RX );
/* Wait for the RSSI to be valid:
* Just having the Radio ON is not enough to read
* the correct RSSI value. The Radio must in RX mode for
* a certain duration.
*/
MRFI_RSSI_VALID_WAIT();
/* Read and convert RSSI to decimal and do offset compensation. */
return( Mrfi_CalculateRssi(mrfiSpiReadReg(RSSI)) );
}
/**************************************************************************************************
* @fn MRFI_Rssi
*
* @brief Returns "live" RSSI value
*
* @param none
*
* @return RSSI value in units of dBm.
**************************************************************************************************
*/
int8_t MRFI_Rssi(void)
{
int8_t rssi;
/* Radio must be in RX state to measure rssi. */
MRFI_ASSERT( mrfiRadioState == MRFI_RADIO_STATE_RX );
/*
* Assuming that the Radio was just turned on, we must wait for
* RSSI to be valid.
*/
MRFI_RSSI_VALID_WAIT();
/* read RSSI value from hardware */
rssi = RSSI;
/* apply offset given in datasheet */
rssi = rssi + MRFI_RSSI_OFFSET;
/* return RSSI value */
return( rssi );
}
/**************************************************************************************************
* @fn MRFI_Transmit
*
* @brief Transmit a packet.
*
* @param pPacket - pointer to packet to transmit
* txType - FORCED or CCA
*
* @return Return code indicates success or failure of transmit:
* MRFI_TX_RESULT_SUCCESS - transmit succeeded
* MRFI_TX_RESULT_FAILED - transmit failed because CCA failed
**************************************************************************************************
*/
uint8_t MRFI_Transmit(mrfiPacket_t * pPacket, uint8_t txType)
{
uint8_t txResult = MRFI_TX_RESULT_SUCCESS;
static uint8_t dsn = 0;
/* radio must be awake to transmit */
MRFI_ASSERT( mrfiRadioState != MRFI_RADIO_STATE_OFF );
/* TX_DONE line status must be low. If high, some state logic problem. */
MRFI_ASSERT(!MRFI_TX_DONE_STATUS());
/* Turn off reciever. We ignore/drop incoming packets during transmit. */
Mrfi_RxModeOff();
/* --------------------------------------
* Populate the IEEE fields in frame
* ------------------------------------
*/
/* set the sequence number, also known as DSN (Data Sequence Number) */
pPacket->frame[MRFI_DSN_OFFSET] = dsn++;
pPacket->frame[MRFI_FCF_OFFSET] = MRFI_FCF_0_7;
pPacket->frame[MRFI_FCF_OFFSET+1] = MRFI_FCF_8_15;
/* ------------------------------------------------------------------
* Write packet to transmit FIFO
* --------------------------------
*/
{
uint8_t txBufLen;
uint8_t frameLen;
uint8_t *p;
/* flush FIFO of any previous transmit that did not go out */
MRFI_RADIO_FLUSH_TX_BUFFER();
/* set point at beginning of outgoing frame */
p = &pPacket->frame[MRFI_LENGTH_FIELD_OFFSET];
/* get number of bytes in the packet (does not include the length byte) */
txBufLen = *p;
/*
* Write the length byte to the FIFO. This length does *not* include the length field
* itself but does include the size of the FCS (generically known as RX metrics) which
* is generated automatically by the radio.
*/
frameLen = txBufLen + MRFI_RX_METRICS_SIZE;
mrfiSpiWriteTxFifo(&frameLen, 1);
/* skip the length field which we already sent to FIFO. */
p++;
/* write packet bytes to FIFO */
mrfiSpiWriteTxFifo(p, txBufLen);
}
/* Forced transmit */
if(txType == MRFI_TX_TYPE_FORCED)
{
/* NOTE: Bug (#1) described in the errata swrz024.pdf for CC2520:
* We never strobe TXON when the radio is in receive state.
* If this is changed, must implement the bug workaround as described in the
* errata (flush the Rx FIFO).
*/
/* strobe transmit */
mrfiSpiCmdStrobe(STXON);
/* wait for transmit to complete */
while (!MRFI_TX_DONE_STATUS());
/* Clear the TX_FRM_DONE exception flag register in the radio. */
mrfiSpiBitClear(EXCFLAG0, 1);
}
else /* CCA Transmit */
{
/* set number of CCA retries */
uint8_t ccaRetries = MRFI_CCA_RETRIES;
MRFI_ASSERT( txType == MRFI_TX_TYPE_CCA );
/* ======================================================================
* CCA Algorithm Loop
* ======================================================================
*/
while(1)
{
/* Turn ON the receiver to perform CCA. Can not call Mrfi_RxModeOn(),
* since that will enable the rx interrupt, which we do not want.
*/
mrfiSpiCmdStrobe(SRXON);
/* Wait for RSSI to be valid. */
MRFI_RSSI_VALID_WAIT();
/* Request transmit on cca */
mrfiSpiCmdStrobe(STXONCCA);
/* If sampled CCA is set, transmit has begun. */
if(MRFI_SAMPLED_CCA())
{
/* wait for transmit to complete */
while( !MRFI_TX_DONE_STATUS() );
/* Clear the TX_FRM_DONE exception flag register in the radio. */
mrfiSpiBitClear(EXCFLAG0, 1);
/* transmit is done. break out of CCA algorithm loop */
break;
}
else
{
/* ------------------------------------------------------------------
* Clear Channel Assessment failed.
* ------------------------------------------------------------------
*/
/* Retry ? */
if(ccaRetries != 0)
{
/* turn off reciever to conserve power during backoff */
Mrfi_RxModeOff();
/* delay for a random number of backoffs */
Mrfi_RandomBackoffDelay();
/* decrement CCA retries before loop continues */
ccaRetries--;
}
else /* No CCA retries left, abort */
{
/* set return value for failed transmit and break */
txResult = MRFI_TX_RESULT_FAILED;
break;
}
}
} /* End CCA Algorithm Loop */
}
/* turn radio back off to put it in a known state */
Mrfi_RxModeOff();
/* If the radio was in RX state when transmit was attempted,
* put it back in RX state.
*/
if(mrfiRadioState == MRFI_RADIO_STATE_RX)
{
Mrfi_RxModeOn();
}
/* return the result of the transmit */
return( txResult );
}
/**************************************************************************************************
* @fn MRFI_Init
*
* @brief Initialize MRFI.
*
* @param none
*
* @return none
**************************************************************************************************
*/
void MRFI_Init(void)
{
/* Configure Output lines */
MRFI_CONFIG_RESETN_PIN_AS_OUTPUT();
MRFI_CONFIG_VREG_EN_PIN_AS_OUTPUT();
/* Configure Input lines */
MRFI_CONFIG_TX_FRAME_DONE_AS_INPUT();
MRFI_CONFIG_FIFO_AS_INPUT();
MRFI_CONFIG_FIFOP_AS_INPUT();
/* Initialize SPI */
mrfiSpiInit();
/* Power up the radio chip */
Mrfi_TurnOnRadioPower();
/* Confirm that we are talking to the right hardware */
MRFI_ASSERT(mrfiSpiReadReg(CHIPID) == MRFI_RADIO_PARTNUM);
/* Random Number Generator:
* The seed value for the randon number generator logic
* is derived from the radio.
*/
/* Set radio in rx mode, but with symbol search disabled. Used for RSSI
* measurments or when we don't care about the received frames.
*/
mrfiSpiWriteReg(FRMCTRL0, FRMCTRL0_RESET_VALUE | RX_MODE_RSSI_ONLY);
/* Turn on the receiver */
mrfiSpiCmdStrobe(SRXON);
/*
* Wait for RSSI to be valid. RANDOM command strobe can be used
* to generate random number only after this.
*/
MRFI_RSSI_VALID_WAIT();
/* Get random byte from the radio */
mrfiRndSeed = mrfiSpiRandomByte();
/*
* The seed value must not be zero. If it is, the pseudo random sequence
* will be always be zero. There is an extremely small chance this seed could
* randomly be zero (more likely some type of hardware problem would cause
* this). If it is zero, initialize it to something.
*/
if(mrfiRndSeed == 0)
{
mrfiRndSeed = 0x80;
}
/* Random number initialization is done. Turn the radio off */
Mrfi_TurnOffRadioPower();
/* Initial radio state is - OFF state */
mrfiRadioState = MRFI_RADIO_STATE_OFF;
/**********************************************************************************
* Compute reply delay scalar
*
* The IEEE radio has a fixed data rate of 250 Kbps. Data rate inference
* from radio regsiters is not necessary for this radio.
*
* The maximum delay needed depends on the MAX_APP_PAYLOAD parameter. Figure
* out how many bits that will be when overhead is included. Bits/bits-per-second
* is seconds to transmit (or receive) the maximum frame. We multiply this number
* by 1000 to find the time in milliseconds. We then additionally multiply by
* 10 so we can add 5 and divide by 10 later, thus rounding up to the number of
* milliseconds. This last won't matter for slow transmissions but for faster ones
* we want to err on the side of being conservative and making sure the radio is on
* to receive the reply. The semaphore monitor will shut it down. The delay adds in
* a fudge factor that includes processing time on peer plus lags in Rx and processing
* time on receiver's side.
*
* **********************************************************************************
*/
#define PLATFORM_FACTOR_CONSTANT 2
#define PHY_PREAMBLE_SYNC_BYTES 8
{
uint32_t bits, dataRate = 250000;
bits = ((uint32_t)((PHY_PREAMBLE_SYNC_BYTES + MRFI_MAX_FRAME_SIZE)*8))*10000;
/* processing on the peer + the Tx/Rx time plus more */
sReplyDelayScalar = PLATFORM_FACTOR_CONSTANT + (((bits/dataRate)+5)/10);
}
/* Random delay: This prevents devices on the same power source from repeated
* transmit collisions on power up.
*/
Mrfi_RandomBackoffDelay();
BSP_ENABLE_INTERRUPTS();
}
/**************************************************************************************************
* @fn MRFI_Transmit
*
* @brief Transmit a packet using CCA algorithm.
*
* @param pPacket - pointer to packet to transmit
*
* @return Return code indicates success or failure of transmit:
* MRFI_TX_RESULT_SUCCESS - transmit succeeded
* MRFI_TX_RESULT_FAILED - transmit failed because CCA failed
**************************************************************************************************
*/
uint8_t MRFI_Transmit(mrfiPacket_t * pPacket, uint8_t txType)
{
static uint8_t dsn = 0;
uint8_t txResult = MRFI_TX_RESULT_SUCCESS;
/* radio must be awake to transmit */
MRFI_ASSERT( mrfiRadioState != MRFI_RADIO_STATE_OFF );
/* ------------------------------------------------------------------
* Initialize hardware for transmit
* -----------------------------------
*/
/* turn off reciever */
Mrfi_RxModeOff();
/* clear 'transmit done' interrupt flag, this bit is tested to see when transmit completes */
RFIRQF1 &= ~IRQ_TXDONE;
/* ------------------------------------------------------------------
* Populate the IEEE fields in frame
* ------------------------------------
*/
/* set the sequence number, also known as DSN (Data Sequence Number) */
pPacket->frame[MRFI_DSN_OFFSET] = dsn;
/* increment the sequence number, value is retained (static variable) for use in next transmit */
dsn++;
/*
* Populate the FCF (Frame Control Field) with the following settings.
*
* bits description setting
* --------------------------------------------------------------------------------------
* 0-2 Frame Type 001 - data frame
* 3 Security Enabled 0 - security disabled
* 4 Frame Pending 0 - no pending data
* 5 Ack Request 0 - no Ack request
* 6 PAN ID Compression 0 - no PAN ID compression
* 7 Reserved 0 - reserved
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
* 8-9 Reserved 00 - reserved
* 10-11 Destination Addressing Mode 10 - PAN ID + 16-bit short address
* 12-13 Frame Version 00 - IEEE Std 802.15.4-2003
* 14-15 Source Addressing Mode 10 - PAN ID + 16-bit short address
*
*/
pPacket->frame[MRFI_FCF_OFFSET] = MRFI_FCF_0_7;
pPacket->frame[MRFI_FCF_OFFSET+1] = MRFI_FCF_8_15;
/* ------------------------------------------------------------------
* Write packet to transmit FIFO
* --------------------------------
*/
{
uint8_t txBufLen;
uint8_t * p;
uint8_t i;
/* flush FIFO of any previous transmit that did not go out */
RFST = ISFLUSHTX;
/* set point at beginning of outgoing frame */
p = &pPacket->frame[MRFI_LENGTH_FIELD_OFFSET];
/* get number of bytes in the packet (does not include the length byte) */
txBufLen = *p;
/*
* Write the length byte to the FIFO. This length does *not* include the length field
* itself but does include the size of the FCS (generically known as RX metrics) which
* is generated automatically by the radio.
*/
RFD = txBufLen + MRFI_RX_METRICS_SIZE;
/* write packet bytes to FIFO */
for (i=0; i<txBufLen; i++)
{
p++;
RFD = *p;
}
}
/* ------------------------------------------------------------------
* Immediate transmit
* ---------------------
*/
if (txType == MRFI_TX_TYPE_FORCED)
{
/* strobe transmit */
RFST = ISTXON;
/* wait for transmit to complete */
while (!(RFIRQF1 & IRQ_TXDONE));
/* transmit is done */
}
else
{
/* ------------------------------------------------------------------
* CCA transmit
* ---------------
*/
MRFI_ASSERT( txType == MRFI_TX_TYPE_CCA );
{
bspIState_t s;
uint8_t txActive;
uint8_t ccaRetries;
/* set number of CCA retries */
ccaRetries = MRFI_CCA_RETRIES;
/* ===============================================================================
* CCA Algorithm Loop
* ====================
*/
for (;;)
{
/* Turn ON the receiver to perform CCA. Can not call Mrfi_RxModeOn(),
* since that will enable the rx interrupt, which we do not want.
*/
RFST = ISRXON;
/*
* Wait for CCA to be valid.
*/
MRFI_RSSI_VALID_WAIT();
/*
* Initiate transmit with CCA. Command is strobed and then status is
* immediately checked. If status shows transmit is active, this means
* that CCA passed and the transmit has gone out. A critical section
* guarantees timing status check happens immediately after strobe.
*/
BSP_ENTER_CRITICAL_SECTION(s);
RFST = ISTXONCCA;
txActive = FSMSTAT1 & SAMPLED_CCA;
BSP_EXIT_CRITICAL_SECTION(s);
/* see transmit went out */
if (txActive)
{
/* ----------| CCA Passed |---------- */
/* wait for transmit to complete */
while (!(RFIRQF1 & IRQ_TXDONE));
/* transmit is done. break out of CCA algorithm loop */
break;
}
else
{
/* ----------| CCA Failed |---------- */
/* if no CCA retries are left, transmit failed so abort */
if (ccaRetries == 0)
{
/* set return value for failed transmit */
txResult = MRFI_TX_RESULT_FAILED;
/* break out of CCA algorithm loop */
break;
}
/* decrement CCA retries before loop continues */
ccaRetries--;
/* turn off reciever to conserve power during backoff */
Mrfi_RxModeOff();
/* delay for a random number of backoffs */
Mrfi_RandomBackoffDelay();
}
}
/*
* --- end CCA Algorithm Loop ---
* =============================================================================== */
}
}
/* turn radio back off to put it in a known state */
Mrfi_RxModeOff();
/* If the radio was in RX state when transmit was attempted,
* put it back in RX state.
*/
if(mrfiRadioState == MRFI_RADIO_STATE_RX)
{
Mrfi_RxModeOn();
}
/* return the result of the transmit */
return( txResult );
}
/**************************************************************************************************
* @fn MRFI_Init
*
* @brief Initialize MRFI.
*
* @param none
*
* @return none
**************************************************************************************************
*/
void MRFI_Init(void)
{
/* ------------------------------------------------------------------
* Run-time integrity checks
* ---------------------------
*/
memset(&mrfiIncomingPacket, 0x0, sizeof(mrfiIncomingPacket));
/* verify the correct radio is installed */
MRFI_ASSERT( CHIPID == MRFI_RADIO_PARTNUM ); /* wrong radio */
MRFI_ASSERT( CHVER >= MRFI_RADIO_MIN_VERSION ); /* obsolete radio version */
/* ------------------------------------------------------------------
* Configure IO ports
* ---------------------------
*/
#if defined(MRFI_PA_LNA_ENABLED) && defined(BSP_BOARD_SRF04EB)
MRFI_BOARD_PA_LNA_CONFIG_PORTS();
MRFI_BOARD_PA_LNA_HGM();
#endif
/* ------------------------------------------------------------------
* Configure clock to use XOSC
* -----------------------------
*/
SLEEPCMD &= ~OSC_PD; /* turn on 16MHz RC and 32MHz XOSC */
while (!(SLEEPSTA & XOSC_STB)); /* wait for 32MHz XOSC stable */
asm("NOP"); /* chip bug workaround */
{
uint16_t i;
/* Require 63us delay for all revs */
for (i=0; i<504; i++)
{
asm("NOP");
}
}
CLKCONCMD = (0x00 | OSC_32KHZ); /* 32MHz XOSC */
while (CLKCONSTA != (0x00 | OSC_32KHZ));
SLEEPCMD |= OSC_PD; /* turn off 16MHz RC */
/* Configure radio registers that should be different from reset values. */
Mrfi_RadioRegConfig();
/* ------------------------------------------------------------------
* Variable Initialization
* -------------------------
*/
#ifdef MRFI_ASSERTS_ARE_ON
PAN_ID0 = 0xFF;
PAN_ID1 = 0xFF;
#endif
/* ------------------------------------------------------------------
* Initialize Random Seed Value
* -------------------------------
*/
/*
* Set radio for infinite reception. Once radio reaches this state,
* it will stay in receive mode regardless RF activity.
*/
FRMCTRL0 = (FRMCTRL0 & ~RX_MODE_MASK) | RX_MODE_INFINITE_RX;
/* turn on the receiver */
RFST = ISRXON;
/* Wait for RSSI to be valid. Once valid, radio is stable and random bits
* can be read.
*/
MRFI_RSSI_VALID_WAIT();
/* put 16 random bits into the seed value */
{
uint16_t rndSeed;
uint8_t i;
rndSeed = 0;
for(i=0; i<16; i++)
{
/* read random bit to populate the random seed */
rndSeed = (rndSeed << 1) | (RFRND & 0x01);
}
/*
* The seed value must not be zero. If it is, the pseudo random sequence will be always be zero.
* There is an extremely small chance this seed could randomly be zero (more likely some type of
* hardware problem would cause this). To solve this, a single bit is forced to be one. This
* slightly reduces the randomness but guarantees a good seed value.
*/
rndSeed |= 0x0080;
/*
* Two writes to RNDL will set the random seed. A write to RNDL copies current contents
* of RNDL to RNDH before writing new the value to RNDL.
*/
RNDL = rndSeed & 0xFF;
RNDL = rndSeed >> 8;
}
/* turn off the receiver, flush RX FIFO just in case something got in there */
RFST = ISRFOFF;
/* flush the rx buffer */
MRFI_RADIO_FLUSH_RX_BUFFER();
/* take receiver out of infinite reception mode; set back to normal operation */
FRMCTRL0 = (FRMCTRL0 & ~RX_MODE_MASK) | RX_MODE_NORMAL;
/* Initial radio state is OFF state */
mrfiRadioState = MRFI_RADIO_STATE_OFF;
/* ------------------------------------------------------------------
* Configure Radio Registers
* ---------------------------
*/
/* disable address filtering */
FRMFILT0 &= ~FRAME_FILTER_EN;
/* reject beacon/ack/cmd frames and accept only data frames,
* when filtering is enabled.
*/
FRMFILT1 &= ~(ACCEPT_BEACON | ACCEPT_ACK | ACCEPT_CMD);
/* don't enable rx after tx is done. */
FRMCTRL1 &= ~RX_ENABLE_ON_TX;
/* set FIFOP threshold to maximum */
FIFOPCTRL = 127;
/* set default channel */
MRFI_SetLogicalChannel( 0 );
/* set default output power level */
MRFI_SetRFPwr(MRFI_NUM_POWER_SETTINGS - 1);
/* enable general RF interrupts */
IEN2 |= RFIE;
/* ------------------------------------------------------------------
* Final Initialization
* -----------------------
*/
/**********************************************************************************
* Compute reply delay scalar
*
* The IEEE radio has a fixed data rate of 250 Kbps. Data rate inference
* from radio regsiters is not necessary for this radio.
*
* The maximum delay needed depends on the MAX_APP_PAYLOAD parameter. Figure
* out how many bits that will be when overhead is included. Bits/bits-per-second
* is seconds to transmit (or receive) the maximum frame. We multiply this number
* by 1000 to find the time in milliseconds. We then additionally multiply by
* 10 so we can add 5 and divide by 10 later, thus rounding up to the number of
* milliseconds. This last won't matter for slow transmissions but for faster ones
* we want to err on the side of being conservative and making sure the radio is on
* to receive the reply. The semaphore monitor will shut it down. The delay adds in
* a platform fudge factor that includes processing time on peer plus lags in Rx and
* processing time on receiver's side. Also includes round trip delays from CCA
* retries. This portion is included in PLATFORM_FACTOR_CONSTANT defined in mrfi.h.
*
* **********************************************************************************
*/
#define PHY_PREAMBLE_SYNC_BYTES 8
{
uint32_t bits, dataRate = 250000;
bits = ((uint32_t)((PHY_PREAMBLE_SYNC_BYTES + MRFI_MAX_FRAME_SIZE)*8))*10000;
/* processing on the peer + the Tx/Rx time plus more */
sReplyDelayScalar = PLATFORM_FACTOR_CONSTANT + (((bits/dataRate)+5)/10);
}
/*
* Random delay - This prevents devices on the same power source from repeated
* transmit collisions on power up.
*/
Mrfi_RandomBackoffDelay();
/* enable global interrupts */
BSP_ENABLE_INTERRUPTS();
}