HAL_TIM_Base_Start_IT(&htim1);

}

// Bring up TCXO and oscillator IC

void wspr_transmit(uint8_t* grid_locator, uint8_t send_alternate)

{

	// Copy 4 digit grid locator to local buffer; null terminate

	for(uint8_t i=0; i<4; i++)

		loc[i] = grid_locator[i];

	loc[4] = '\0';

    // Set power to altitude in m / 150

    uint8_t altscaled = gps_getdata()->altitude / 150;

    if(altscaled > 60)

        altscaled = 60;

    // If alternate packet, send 0XFXXEN82XX

    if(send_alternate)

    {

        /////////////////////////////////////////////////

        // Composite altitude and sub-maidenhead locator

        ///////////////////////////////////////////////// 

        // Ciel at 21,340 meters

        if(altitude_mod > 1067)

            altitude_mod = 1067; // Don't overflow into maidenhead!

        // Compose composite altitude (lsbs) with maidenhead locator (msbs)

        uint32_t subalt = (1068 * maiden_ext) + (gps_getdata()->altitude / 20);

        ////////////////////////////////////////////

        // Encode extended maidenhead and altitude

        ////////////////////////////////////////////

        // Static set first char: balloon ID (invalid call)

        call[0] = '0';

        // Split into chunks of valmax 36, 26, 26, 26

        // Mask off following 3 26valmax fields

        uint32_t chunk = subalt / 26 / 26 / 26; 

        // Encode to callsign

        if(chunk < 10)

        call[1] = call_orig[1];

        call[2] = call_orig[2];

        call[3] = call_orig[3];

        call[4] = call_orig[4];

        call[5] = call_orig[5];

        call[6] = call_orig[6];

        dbm = DBM_ORIG; 

    }

    // Start timer for WSPR

    __TIM1_CLK_ENABLE();

    htim1.Instance = TIM1;

    htim1.Init.Prescaler = 512 / 4; // FIXED gives 64us ticks from 2mhz clock // gives 64uS ticks from 8MHz ahbclk

    htim1.Init.CounterMode = TIM_COUNTERMODE_UP;

    htim1.Init.Period = ctc; // Count up to this value (how many 64uS ticks per symbol)

    htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

    htim1.Init.RepetitionCounter = 0;

    HAL_TIM_Base_Init(&htim1);

    HAL_TIM_Base_Start_IT(&htim1);

    HAL_NVIC_SetPriority(TIM1_BRK_UP_TRG_COM_IRQn, 0, 0);

    HAL_NVIC_EnableIRQ(TIM1_BRK_UP_TRG_COM_IRQn);

    HAL_GPIO_WritePin(OSC_NOTEN, 0);

    HAL_GPIO_WritePin(TCXO_EN, 1);

    HAL_Delay(100);

    // Bring up the chip

    i2c_init();

    si5351_init(i2c_get(), SI5351_CRYSTAL_LOAD_8PF, 0);

    si5351_set_correction(0);

    //si5351_set_pll(SI5351_PLL_FIXED, SI5351_PLLA);

    //si5351_set_ms_source(SI5351_CLK0, SI5351_PLLA);

    si5351_set_freq(WSPR_DEFAULT_FREQ * 100, 0, SI5351_CLK0);

//    si5351_drive_strength(SI5351_CLK0, SI5351_DRIVE_8MA); // Set for max power if desired (8ma max)

    si5351_drive_strength(SI5351_CLK0, SI5351_DRIVE_6MA); // Set for max power if desired (8ma max)

    si5351_output_enable(SI5351_CLK0, 1);

    //si5351_pll_reset(SI5351_PLLA);

    // Make sure the other outputs of the SI5351 are disabled

    si5351_output_enable(SI5351_CLK1, 0); // Disable the clock initially

    si5351_output_enable(SI5351_CLK2, 0); // Disable the clock initially

    // disable clock powers

    si5351_set_clock_pwr(SI5351_CLK1, 0);

    si5351_set_clock_pwr(SI5351_CLK2, 0);