void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName clk, PinName cs)
{
    CMU_ClockEnable(cmuClock_HFPER, true);
    spi_preinit(obj, mosi, miso, clk, cs);
    CMU_ClockEnable(spi_get_clock_tree(obj), true);
    usart_init(obj, 100000, usartDatabits8, true, usartClockMode0);

    spi_enable_pins(obj, true, mosi, miso, clk, cs);
    spi_enable(obj, true);
}
void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName clk)
{
    // CS is currently not part of the mbed HAL
    PinName cs = NC;

    CMU_ClockEnable(cmuClock_HFPER, true);
    spi_preinit(obj, mosi, miso, clk, cs);
    CMU_ClockEnable(spi_get_clock_tree(obj), true);
    usart_init(obj, 100000, usartDatabits8, true, usartClockMode0);

    spi_enable_pins(obj, true, mosi, miso, clk, cs);
    spi_enable(obj, true);
}