nrf_radio_signal_callback_return_param_t * radio_callback(uint8_t signal_type)
{
    LOG_MSG("radio_callback: %d\n", signal_type);
    switch(signal_type)
    {
        case NRF_RADIO_CALLBACK_SIGNAL_TYPE_START:
            LOG_MSG("NRF_RADIO_CALLBACK_SIGNAL_TYPE_START\n");
            //Start of the timeslot - set up timer interrupt
            signal_callback_return_param.params.request.p_next = NULL;
            signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_NONE;

            NRF_TIMER0->MODE = TIMER_MODE_MODE_Timer;  // Set the timer in Counter Mode
            NRF_TIMER0->TASKS_STOP = 1;               // clear the task first to be usable for later
            NRF_TIMER0->TASKS_CLEAR = 1;               // clear the task first to be usable for later
            NRF_TIMER0->PRESCALER = 6;                             //Set prescaler. Higher number gives slower timer. Prescaler = 0 gives 16MHz timer
            NRF_TIMER0->CC[0] = 1000;                             //Set value for TIMER2 compare register 0
            NRF_TIMER0->INTENCLR    = 0xffffffff;
            NRF_TIMER0->INTENSET    = TIMER_INTENSET_COMPARE0_Msk;
            NVIC_ClearPendingIRQ(TIMER0_IRQn);
            NVIC_EnableIRQ(TIMER0_IRQn);
            NRF_TIMER0->TASKS_START = 1;
            break;

        case NRF_RADIO_CALLBACK_SIGNAL_TYPE_RADIO:
            LOG_MSG("NRF_RADIO_CALLBACK_SIGNAL_TYPE_RADIO\n");
            signal_callback_return_param.params.request.p_next = NULL;
            signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_NONE;
            break;

        case NRF_RADIO_CALLBACK_SIGNAL_TYPE_TIMER0:
            LOG_MSG("NRF_RADIO_CALLBACK_SIGNAL_TYPE_TIMER0\n");
            //Timer interrupt - do graceful shutdown - schedule next timeslot
            // configure_next_event_normal();
            // signal_callback_return_param.params.request.p_next = &m_timeslot_request;
            // signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_REQUEST_AND_END;
            signal_callback_return_param.params.extend.length_us = 300000; // 300ms
            signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_EXTEND;
            break;
        case NRF_RADIO_CALLBACK_SIGNAL_TYPE_EXTEND_SUCCEEDED:
            LOG_MSG("NRF_RADIO_CALLBACK_SIGNAL_TYPE_EXTEND_SUCCEEDED\n");
            NRF_TIMER0->TASKS_CLEAR = 1;
            break;
        case NRF_RADIO_CALLBACK_SIGNAL_TYPE_EXTEND_FAILED:
            LOG_MSG("NRF_RADIO_CALLBACK_SIGNAL_TYPE_EXTEND_FAILED\n");
            //Try scheduling a new timeslot
            // configure_next_event_earliest();
            // signal_callback_return_param.params.request.p_next = &m_timeslot_request;
            // signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_REQUEST_AND_END;
            signal_callback_return_param.params.request.p_next = NULL;
            signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_END;
            break;
        default:
            //No implementation needed
            break;
    }
    LOG_MSG("radio_callback: return\n");
    return (&signal_callback_return_param);
}