C++ pal_trx_reg_write函数代码示例

/**
 * @brief Configures the transceiver
 *
 * This function is called to configure the transceiver after reset.
 */
static void trx_config(void)
{
    /* After we have initialized a proper seed for rand(),
     * the transceiver's CSMA seed can be initialized.
     * It needs to be assured that a seed for function rand()
     * had been generated before.
     */
    /*
     * Init the SEED value of the CSMA backoff algorithm.
     */
    uint16_t rand_value = (uint16_t)rand();
    pal_trx_reg_write(RG_CSMA_SEED_0, (uint8_t)rand_value);
    pal_trx_bit_write(SR_CSMA_SEED_1, (uint8_t)(rand_value >> 8));

    pal_trx_bit_write(SR_AACK_SET_PD, PD_ACK_BIT_SET_ENABLE); /* ACKs for data requests, indicate pending data */
    pal_trx_bit_write(SR_RX_SAFE_MODE, RX_SAFE_MODE_ENABLE);  /* Enable buffer protection mode */
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_DEFAULT);
    pal_trx_reg_write(0x156, 0xFF); /* RPC feature configuration. */

#if (ANTENNA_DIVERSITY == 1)
    // Use antenna diversity
    pal_trx_bit_write(SR_ANT_CTRL, ANTENNA_DEFAULT);
    pal_trx_bit_write(SR_PDT_THRES, THRES_ANT_DIV_ENABLE);
    pal_trx_bit_write(SR_ANT_DIV_EN, ANT_DIV_ENABLE);
    pal_trx_bit_write(SR_ANT_EXT_SW_EN, ANT_EXT_SW_ENABLE);
#endif

#ifdef CCA_ED_THRESHOLD
    /*
     * Set CCA ED Threshold to other value than standard register due to
     * board specific loss (see pal_config.h). */
    pal_trx_bit_write(SR_CCA_ED_THRES, CCA_ED_THRESHOLD);
#endif
}

/**
 * @brief Starts continuous transmission on current channel
 */
void tfa_continuous_tx_start(continuous_tx_mode_t tx_mode)
{
    uint8_t txcwdata[127];

    pal_trx_bit_write(SR_TX_AUTO_CRC_ON, TX_AUTO_CRC_DISABLE);
    pal_trx_reg_write(RG_TRX_STATE, CMD_TRX_OFF);
    pal_trx_reg_write(0x0176, 0x0F);     /*TST_CTRL_DIGI*/
    /* Here: use 2MBPS mode for PSD measurements.
     * Omit the two following lines, if 250k mode is desired for PRBS mode. */
    pal_trx_bit_write(SR_OQPSK_DATA_RATE, ALTRATE_2MBPS);
    pal_trx_reg_write(RG_RX_CTRL, 0xA7);
    if (tx_mode == CW_MODE)
    {
        txcwdata[0] = 1;    // length
        // Step 11 - frame buffer write access
        txcwdata[1] = 0x00; // f=fch-0.5 MHz; set value to 0xFF for f=fch+0.5MHz
        pal_trx_frame_write(txcwdata, 2);
    }
    else    // PRBS mode
    {
        txcwdata[0] = 127;   // = max length
        for (uint8_t i = 1; i < 128; i++)
        {
            txcwdata[i] = (uint8_t)rand();
        }
        pal_trx_frame_write(txcwdata, 128);
    }

    pal_trx_reg_write(RG_PART_NUM, 0x54);
    pal_trx_reg_write(RG_PART_NUM, 0x46);
    set_trx_state(CMD_PLL_ON);
    PAL_SLP_TR_HIGH();
    PAL_SLP_TR_LOW();
}

/**
 * @brief Switches the PLL on
 */
static void switch_pll_on(void)
{
    uint32_t start_time;
    uint32_t current_time;

    /* Check if trx is in TRX_OFF; only from PLL_ON the following procedure is applicable */
    if (pal_trx_bit_read(SR_TRX_STATUS) != TRX_OFF)
    {
        ASSERT("Switch PLL_ON failed, because trx is not in TRX_OFF" == 0);
        return;
    }

    /* Clear all pending trx interrupts */
    pal_trx_reg_read(RG_IRQ_STATUS);
    /* Get current IRQ mask */
    uint8_t trx_irq_mask = pal_trx_reg_read(RG_IRQ_MASK);
    /* Enable transceiver's PLL lock interrupt */
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_0_PLL_LOCK);
    ENTER_TRX_REGION(); // Disable trx interrupt handling

    /* Switch PLL on */
    pal_trx_reg_write(RG_TRX_STATE, CMD_PLL_ON);
    pal_get_current_time(&start_time);

    /* Wait for transceiver interrupt: check for IRQ line */
    while (PAL_TRX_IRQ_HIGH() == false)
    {
        /* Handle errata "potential long PLL settling duration". */
        pal_get_current_time(&current_time);
        if (pal_sub_time_us(current_time, start_time) > PLL_LOCK_DURATION_MAX_US)
        {
            uint8_t reg_value;

            reg_value = pal_trx_reg_read(RG_PLL_CF);
            if (reg_value & 0x01)
            {
                reg_value &= 0xFE;
            }
            else
            {
                reg_value |= 0x01;
            }
            pal_trx_reg_write(RG_PLL_CF, reg_value);
            pal_get_current_time(&start_time);
        }
        /* Wait until trx line has been raised. */
    }

    /* Clear PLL lock interrupt at trx */
    pal_trx_reg_read(RG_IRQ_STATUS);
    /* Clear MCU's interrupt flag */
    pal_trx_irq_flag_clr();
    LEAVE_TRX_REGION();    // Enable trx interrupt handling again
    /* Restore transceiver's interrupt mask. */
    pal_trx_reg_write(RG_IRQ_MASK, trx_irq_mask);
}

/*
 * \brief Starts ED Scan
 *
 * This function starts an ED Scan for the scan duration specified by the
 * MAC layer.
 *
 * \param scan_duration Specifies the ED scan duration in symbols
 *
 * \return MAC_SUCCESS - ED scan duration timer started successfully
 *         TAL_BUSY - TAL is busy servicing the previous request from MAC
 *         TAL_TRX_ASLEEP - Transceiver is currently sleeping
 *         FAILURE otherwise
 */
retval_t tal_ed_start(uint8_t scan_duration)
{
    /*
     * Check if the TAL is in idle state. Only in idle state it can
     * accept and ED request from the MAC.
     */
    if (TAL_IDLE != tal_state)
    {
        if (tal_trx_status == TRX_SLEEP)
        {
            return TAL_TRX_ASLEEP;
        }
        else
        {
            Assert("TAL is TAL_BUSY" == 0);
            return TAL_BUSY;
        }
    }

    /*
     * Disable the transceiver interrupts to prevent frame reception
     * while performing ED scan.
     */
    pal_trx_irq_dis();  /* Disable transceiver main interrupt. */
    set_trx_state(CMD_FORCE_PLL_ON);
    pal_trx_reg_read(RG_IRQ_STATUS);        /* Clear existing interrupts */
    pal_trx_bit_write(SR_RX_PDT_DIS, RX_DISABLE);
    pal_trx_irq_init((FUNC_PTR)trx_ed_irq_handler_cb);
    pal_trx_bit_write(SR_IRQ_MASK, TRX_IRQ_CCA_ED_READY); /* enable interrupt */
    pal_trx_irq_en();   /* Enable main transceiver interrupt. */

    /* Make sure that receiver is switched on. */
    if (set_trx_state(CMD_RX_ON) != RX_ON)
    {
        /* Restore previous configuration */
        pal_trx_bit_write(SR_RX_PDT_DIS, RX_ENABLE);
        pal_trx_irq_init((FUNC_PTR)trx_irq_handler_cb);
        pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_DEFAULT); /* enable TRX_END interrupt */
        pal_trx_irq_en();   /* Enable main transceiver interrupt. */

        return FAILURE;
    }

    // write dummy value to start measurement
    pal_trx_reg_write(RG_PHY_ED_LEVEL, 0xFF);

    /* Perform ED in TAL_ED_RUNNING state. */
    tal_state = TAL_ED_RUNNING;

    max_ed_level = 0;   // reset max value

    sampler_counter = CALCULATE_SYMBOL_TIME_SCAN_DURATION(scan_duration) / ED_SAMPLE_DURATION_SYM;

    return MAC_SUCCESS;
}

/**
 * @brief Generates a 16-bit random number used as initial seed for srand()
 *
 * This function generates a 16-bit random number by means of using the
 * Random Number Generator from the transceiver.
 * The Random Number Generator generates 2-bit random values. These 2-bit
 * random values are concatenated to the required 16-bit random seed.
 *
 * The generated random 16-bit number is feed into function srand()
 * as initial seed.
 *
 * The transceiver state is initally set to RX_ON.
 * After the completion of the random seed generation, the
 * trancseiver is set to TRX_OFF.
 *
 * As a prerequisite the preamble detector must not be disabled.
 *
 * Also in case the function is called from a different state than TRX_OFF,
 * additional trx state handling is required, such as reading the original
 * value and restoring this state after finishing the sequence.
 * Since in our case the function is called from TRX_OFF, this is not required
 * here.
 */
void tal_generate_rand_seed(void)
{
    uint16_t seed = 0;
    uint8_t cur_random_val = 0;

    /* RPC could influence the randomness; therefore disable it here. */
    uint8_t previous_RPC_value = pal_trx_reg_read(RG_TRX_RPC);
    pal_trx_reg_write(RG_TRX_RPC, 0xC1);

    /*
     * We need to disable TRX IRQs while generating random values in RX_ON,
     * we do not want to receive frames at this point of time at all.
     */
    ENTER_TRX_REGION();

    /* Ensure that PLL has locked and receive mode is reached. */
    tal_trx_status_t trx_state;
    do
    {
        trx_state = set_trx_state(CMD_RX_ON);
    }
    while (trx_state != RX_ON);

    /* Ensure that register bit RX_PDT_DIS is set to 0. */
    pal_trx_bit_write(SR_RX_PDT_DIS, RX_ENABLE);

    /*
     * The 16-bit random value is generated from various 2-bit random values.
     */
    for (uint8_t i = 0; i < 8; i++)
    {
        /* Now we can safely read the 2-bit random number. */
        cur_random_val = pal_trx_bit_read(SR_RND_VALUE);
        seed = seed << 2;
        seed |= cur_random_val;
        PAL_WAIT_1_US();    // wait that the random value gets updated
    }

    set_trx_state(CMD_FORCE_TRX_OFF);

    /*
     * Now we need to clear potential pending TRX IRQs and
     * enable the TRX IRQs again.
     */
    pal_trx_reg_read(RG_IRQ_STATUS);
    pal_trx_irq_flag_clr();
    LEAVE_TRX_REGION();

    /* Set the seed for the random number generator. */
    srand(seed);

    /* Restore RPC settings. */
    pal_trx_reg_write(RG_TRX_RPC, previous_RPC_value);
}

/**
 * @brief Write all shadow PIB variables to the transceiver
 *
 * This function writes all shadow PIB variables to the transceiver.
 * It is assumed that the radio does not sleep.
 */
void write_all_tal_pib_to_trx(void)
{
    uint8_t *ptr_to_reg;

    ptr_to_reg = (uint8_t *)&tal_pib.PANId;
    for (uint8_t i = 0; i < 2; i++)
    {
        pal_trx_reg_write((RG_PAN_ID_0 + i), *ptr_to_reg);
        ptr_to_reg++;
    }

    ptr_to_reg = (uint8_t *)&tal_pib.IeeeAddress;
    for (uint8_t i = 0; i < 8; i++)
    {
        pal_trx_reg_write((RG_IEEE_ADDR_0 + i), *ptr_to_reg);
        ptr_to_reg++;
    }

    ptr_to_reg = (uint8_t *)&tal_pib.ShortAddress;
    for (uint8_t i = 0; i < 2; i++)
    {
        pal_trx_reg_write((RG_SHORT_ADDR_0 + i), *ptr_to_reg);
        ptr_to_reg++;
    }

    /* configure TX_ARET; CSMA and CCA */
    pal_trx_bit_write(SR_CCA_MODE, tal_pib.CCAMode);
    pal_trx_bit_write(SR_MIN_BE, tal_pib.MinBE);

    pal_trx_bit_write(SR_AACK_I_AM_COORD, tal_pib.PrivatePanCoordinator);

    /* set phy parameter */
    pal_trx_bit_write(SR_MAX_BE, tal_pib.MaxBE);

#ifdef HIGH_DATA_RATE_SUPPORT
    apply_channel_page_configuration(tal_pib.CurrentPage);
#endif

    pal_trx_bit_write(SR_CHANNEL, tal_pib.CurrentChannel);
    {
        uint8_t reg_value;

        reg_value = convert_phyTransmitPower_to_reg_value(tal_pib.TransmitPower);
        pal_trx_bit_write(SR_TX_PWR, reg_value);
    }

#ifdef PROMISCUOUS_MODE
    if (tal_pib.PromiscuousMode)
    {
        set_trx_state(CMD_RX_ON);
    }
#endif
}

/*
 * \brief Scan done
 *
 * This function updates the max_ed_level and invokes the callback function
 * tal_ed_end_cb().
 *
 * \param parameter unused callback parameter
 */
void ed_scan_done(void)
{
    pal_trx_bit_write(SR_RX_PDT_DIS, RX_ENABLE);
    pal_trx_irq_init((FUNC_PTR)trx_irq_handler_cb);
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_DEFAULT); /* enable TRX_END interrupt */
    pal_trx_irq_en();   /* Enable transceiver main interrupt. */

    tal_state = TAL_IDLE;   // ed scan is done
    set_trx_state(CMD_RX_AACK_ON);

#ifndef TRX_REG_RAW_VALUE
    /*
     * Scale ED result.
     * Clip values to 0xFF if > -35dBm
     */
    if (max_ed_level > CLIP_VALUE_REG)
    {
        max_ed_level = 0xFF;
    }
    else
    {
        max_ed_level = (uint8_t)(((uint16_t)max_ed_level * 0xFF) / CLIP_VALUE_REG);
    }
#endif
    tal_ed_end_cb(max_ed_level);
}

trx_retval_t tal_init(void)
{
	if (trx_init() != TRX_SUCCESS) {
		return TRX_FAILURE;
	}

	/*
	 * Do the reset stuff.
	 * Generate random seed.
	 */
	if (internal_tal_reset() != TRX_SUCCESS) {
		return TRX_FAILURE;
	}

	/* Set the default CCA mode. */
	pal_trx_bit_write(SR_CCA_MODE, CCA_MODE_DEFAULT);

	/* Default configuration to perform auto CSMA-CA */
	pal_trx_reg_write(RG_CSMA_BE, ((MAXBE_DEFAULT << 4) | MINBE_DEFAULT));
	pal_trx_bit_write(SR_MAX_CSMA_RETRIES, MAX_CSMA_BACKOFFS_DEFAULT);

	/* Set the trx in promiscuous mode to receive all frame with CRC OK */
	pal_trx_bit_write(SR_AACK_PROM_MODE, PROM_MODE_ENABLE);

	/* Configuration to perform auto CRC for transmission */
	pal_trx_bit_write(SR_TX_AUTO_CRC_ON, TX_AUTO_CRC_ENABLE);

	return TRX_SUCCESS;
}

/**
 * @brief Initializes the transceiver
 *
 * This function is called to initialize the transceiver.
 *
 * @return MAC_SUCCESS  if the transceiver state is changed to TRX_OFF and the
 *                 current device part number and version number are correct;
 *         FAILURE otherwise
 */
static retval_t trx_init(void)
{
    tal_trx_status_t trx_status;
    uint8_t poll_counter = 0;

    PAL_RST_HIGH();
    PAL_SLP_TR_LOW();

    /* Wait typical time of timer TR1. */
    pal_timer_delay(P_ON_TO_CLKM_AVAILABLE_TYP_US);

    /* Apply reset pulse */
    PAL_RST_LOW();
    pal_timer_delay(RST_PULSE_WIDTH_US);
    PAL_RST_HIGH();

#if !(defined FPGA_EMULATION)
    do
    {
        /* Wait not more than max. value of TR1. */
        if (poll_counter == P_ON_TO_CLKM_ATTEMPTS)
        {
            return FAILURE;
        }
        /* Wait a short time interval. */
        pal_timer_delay(TRX_POLL_WAIT_TIME_US);
        poll_counter++;
        /* Check if AT86RF233 is connected; omit manufacturer id check */
    }
    while (pal_trx_reg_read(RG_PART_NUM) != PART_NUM_AT86RF233);
#endif  /* !defined FPGA_EMULATION */

    /* Verify that TRX_OFF can be written */
    pal_trx_reg_write(RG_TRX_STATE, CMD_TRX_OFF);

    /* Verify that the trx has reached TRX_OFF. */
    poll_counter = 0;
    do
    {
        /* Wait a short time interval. */
        pal_timer_delay(TRX_POLL_WAIT_TIME_US);

        trx_status = (tal_trx_status_t)pal_trx_bit_read(SR_TRX_STATUS);

        /* Wait not more than max. value of TR15. */
        if (poll_counter == P_ON_TO_TRX_OFF_ATTEMPTS)
        {
#if (DEBUG > 0)
            pal_alert();
#endif
            return FAILURE;
        }
        poll_counter++;
    }
    while (trx_status != TRX_OFF);

    tal_trx_status = TRX_OFF;

    return MAC_SUCCESS;
}

/**
 * @brief Scan done
 *
 * This function updates the max_ed_level and invokes the callback function
 * tal_ed_end_cb().
 *
 * @param parameter unused callback parameter
 */
void ed_scan_done(void)
{
    /* Restore previous configuration */
    pal_trx_bit_write(SR_RX_PDT_DIS, RX_ENABLE);
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_DEFAULT);

    tal_state = TAL_IDLE;   // ed scan is done
    set_trx_state(CMD_RX_AACK_ON);

#ifndef TRX_REG_RAW_VALUE
    /*
     * Scale ED result.
     * Clip values to 0xFF if > -35dBm
     */
    if (max_ed_level > CLIP_VALUE_REG)
    {
        max_ed_level = 0xFF;
    }
    else
    {
        max_ed_level = (uint8_t)(((uint16_t)max_ed_level * 0xFF) / CLIP_VALUE_REG);
    }
#endif
    tal_ed_end_cb(max_ed_level);
}

/**
 * @brief ED Scan Interrupt
 *
 * This function handles an ED done interrupt from the transceiver.
 */
static void trx_ed_irq_handler_cb(void)
{
    uint8_t ed_value;

    /* Read the ED Value. */
    ed_value = pal_trx_reg_read(RG_PHY_ED_LEVEL);

    /*
     * Update the peak ED value received, if greater than the previously
     * read ED value.
     */
    if (ed_value > max_ed_level)
    {
        max_ed_level = ed_value;
    }

    /* Start next ED sampling */
    sampler_counter--;
    if (sampler_counter > 0)
    {
        // write dummy value to start measurement
        pal_trx_reg_write(RG_PHY_ED_LEVEL, 0xFF);
    }
    else
    {
        tal_state = TAL_ED_DONE;
    }
}

/**
 * @brief Starts ED Scan
 *
 * This function starts an ED Scan for the scan duration specified by the
 * MAC layer.
 *
 * @param scan_duration Specifies the ED scan duration in symbols
 *
 * @return MAC_SUCCESS - ED scan duration timer started successfully
 *         TAL_BUSY - TAL is busy servicing the previous request from MAC
 *         TAL_TRX_ASLEEP - Transceiver is currently sleeping
 *         FAILURE otherwise
 */
retval_t tal_ed_start(uint8_t scan_duration)
{
    /*
     * Check if the TAL is in idle state. Only in idle state it can
     * accept and ED request from the MAC.
     */
    if (TAL_IDLE != tal_state)
    {
        if (tal_trx_status == TRX_SLEEP)
        {
            return TAL_TRX_ASLEEP;
        }
        else
        {
            ASSERT("TAL is TAL_BUSY" == 0);
            return TAL_BUSY;
        }
    }

    set_trx_state(CMD_FORCE_PLL_ON);
    pal_trx_bit_write(SR_RX_PDT_DIS, RX_DISABLE);
    pal_trx_irq_flag_clr_cca_ed();
    pal_trx_irq_init_cca_ed((FUNC_PTR)trx_ed_irq_handler_cb);
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_CCA_ED_READY);

    /* Make sure that receiver is switched on. */
    if (set_trx_state(CMD_RX_ON) != RX_ON)
    {
        /* Restore previous configuration */
        pal_trx_bit_write(SR_RX_PDT_DIS, RX_ENABLE);
        pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_DEFAULT);

        return FAILURE;
    }

    /* Perform ED in TAL_ED_RUNNING state. */
    tal_state = TAL_ED_RUNNING;

    max_ed_level = 0;   // reset max value

    sampler_counter = CALCULATE_SYMBOL_TIME_SCAN_DURATION(scan_duration) / ED_SAMPLE_DURATION_SYM;

    // write dummy value to start measurement
    pal_trx_reg_write(RG_PHY_ED_LEVEL, 0xFF);

    return MAC_SUCCESS;
}

/**
 * @brief Generates a 16-bit random number used as initial seed for srand()
 *
 * This function generates a 16-bit random number by means of using the
 * Random Number Generator from the transceiver.
 * The Random Number Generator generates 2-bit random values. These 2-bit
 * random values are concatenated to the required 16-bit random seed.
 *
 * The generated random 16-bit number is feed into function srand()
 * as initial seed.
 *
 * The transceiver state is initally set to RX_ON.
 * After the completion of the random seed generation, the
 * trancseiver is set to TRX_OFF.
 *
 * As a prerequisite the preamble detector must not be disabled.
 *
 * Also in case the function is called from a different state than TRX_OFF,
 * additional trx state handling is required, such as reading the original
 * value and restoring this state after finishing the sequence.
 * Since in our case the function is called from TRX_OFF, this is not required
 * here.
 */
void tal_generate_rand_seed(void)
{
    uint16_t seed = 0;
    uint8_t cur_random_val = 0;

    /* Ensure that PLL has locked and receive mode is reached. */
    tal_trx_status_t trx_state;
    do
    {
        trx_state = set_trx_state(CMD_RX_ON);
    }
    while (trx_state != RX_ON);

    /* Ensure that register bit RX_PDT_DIS is set to 0. */
    pal_trx_bit_write(SR_RX_PDT_DIS, RX_ENABLE);

    /*
     * We need to disable TRX IRQs while generating random values in RX_ON,
     * we do not want to receive frames at this point of time at all.
     */
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_NONE);

    /*
     * The 16-bit random value is generated from various 2-bit random values.
     */
    for (uint8_t i = 0; i < 8; i++)
    {
        /* Now we can safely read the 2-bit random number. */
        cur_random_val = pal_trx_bit_read(SR_RND_VALUE);
        seed = seed << 2;
        seed |= cur_random_val;
        PAL_WAIT_1_US();    // wait that the random value gets updated
    }

    set_trx_state(CMD_FORCE_TRX_OFF);

    /*
     * Now we need to clear potential pending TRX IRQs and
     * enable the TRX IRQs again.
     */
    pal_trx_reg_write(RG_IRQ_STATUS, 0xFF);
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_DEFAULT);

    /* Set the seed for the random number generator. */
    srand(seed);
}

/**
 * @brief Switches the PLL on
 */
static void switch_pll_on(void)
{
    trx_irq_reason_t irq_status;
    uint32_t start_time, now;

    /* Check if trx is in TRX_OFF; only from PLL_ON the following procedure is applicable */
    if (pal_trx_bit_read(SR_TRX_STATUS) != TRX_OFF)
    {
        ASSERT("Switch PLL_ON failed, because trx is not in TRX_OFF" == 0);
        return;
    }

    /* use the IRQ status register checking for the actual PLL status */
    pal_trx_irq_dis();
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_PLL_LOCK);  /* allow PLL lock IRQ only*/
    pal_trx_reg_read(RG_IRQ_STATUS);    /* clear PLL lock bit */

    /* Switch PLL on */
    pal_trx_reg_write(RG_TRX_STATE, CMD_PLL_ON);

    /* Check if PLL has been locked. */
    pal_get_current_time(&start_time);
    while (1)
    {
        irq_status = (trx_irq_reason_t)pal_trx_reg_read(RG_IRQ_STATUS);
        if (irq_status & TRX_IRQ_PLL_LOCK)
        {
            break;  // PLL is locked now
        }

        /* Check if polling needs too much time. */
        pal_get_current_time(&now);
        if (pal_sub_time_us(now, start_time) > (10 * PLL_LOCK_TIME_US))
        {
            /* leave poll loop and throw assertion */
#if (DEBUG > 0)
            ASSERT("PLL switch failed" == 0);
#endif
            break;
        }
    }
    pal_trx_irq_flag_clr();
    pal_trx_reg_write(RG_IRQ_MASK, TRX_IRQ_TRX_END); /* enable TRX_END interrupt */

    pal_trx_irq_en();
}

/**
 * @brief Perform a single ED measurement
 *
 * @return ed_value Result of the measurement
 *         If the build switch TRX_REG_RAW_VALUE is defined, the transceiver's
 *         register value is returned.
 */
uint8_t tfa_ed_sample(void)
{
    trx_irq_reason_t trx_irq_cause;
    uint8_t ed_value;
    tal_trx_status_t trx_status;

    /* Make sure that receiver is switched on. */
    do
    {
        trx_status = set_trx_state(CMD_RX_ON);
    }
    while (trx_status != RX_ON);

    /*
     * Disable the transceiver interrupts to prevent frame reception
     * while performing ED scan.
     */
    pal_trx_bit_write(SR_RX_PDT_DIS, RX_DISABLE);

    /* Write dummy value to start measurement. */
    pal_trx_reg_write(RG_PHY_ED_LEVEL, 0xFF);

    /* Wait for ED measurement completion. */
    pal_timer_delay(TAL_CONVERT_SYMBOLS_TO_US(ED_SAMPLE_DURATION_SYM));
    do
    {
        trx_irq_cause = (trx_irq_reason_t)pal_trx_reg_read(RG_IRQ_STATUS);
    }
    while ((trx_irq_cause & TRX_IRQ_CCA_ED_READY) != TRX_IRQ_CCA_ED_READY);

    /* Read the ED Value. */
    ed_value = pal_trx_reg_read(RG_PHY_ED_LEVEL);

#ifndef TRX_REG_RAW_VALUE
    /*
     * Scale ED result.
     * Clip values to 0xFF if > -35dBm
     */
    if (ed_value > CLIP_VALUE_REG)
    {
        ed_value = 0xFF;
    }
    else
    {
        ed_value = (uint8_t)(((uint16_t)ed_value * 0xFF) / CLIP_VALUE_REG);
    }
#endif

    /* Clear IRQ register */
    pal_trx_reg_read(RG_IRQ_STATUS);
    /* Enable reception agian */
    pal_trx_bit_write(SR_RX_PDT_DIS, RX_ENABLE);
    /* Switch receiver off again */
    set_trx_state(CMD_TRX_OFF);

    return ed_value;
}