RE: How to implement bit banging in NCS via TIME+GPIOTE+PPI

Quay — Tue, 13 Aug 2024 07:17:43 GMT

Hi Susheel,

Thank you for your support.

RE: How to implement bit banging in NCS via TIME+GPIOTE+PPI

Susheel Nuguru — Tue, 13 Aug 2024 06:54:17 GMT

Quay,

The managing of Dali tx and rx is an IP in itself which many Lighting companies do it themselves and the efficiency of the implementation is never shared. Unfortunately we do not have a template to show to you on how this can be done.

The timer can be setup somthing like below to achieve 1200bps baud on the Dali transport layer

static struct dali_timer_data dali_timer_data =
{
    .p_instance = NRFX_TIMER_INSTANCE(CONFIG_DALI_TIMER_INSTANCE),
    .cfg = 
    {
        .frequency = NRF_TIMER_FREQ_16MHz,
        .mode = NRF_TIMER_MODE_TIMER,
        .bit_width = NRF_TIMER_BIT_WIDTH_32,
        .interrupt_priority = 0
    }
};

static void timer_handler(nrf_timer_event_t event_type, void *p_context)
{
    struct dali_timer *timer = (struct dali_timer *)p_context;
    struct dali_timer_data * timer_data = (struct dali_timer_data *)timer->timer_data;
    if(event_type == NRF_TIMER_EVENT_COMPARE0)
    {
        timer->callback(timer, timer->user_data);
    }
}

GPIOTE and PPI can be configured something like this

NRF_GPIOTE->CONFIG[GPIOTE_CH_OUT] = GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos |
                                    GPIOTE_CONFIG_POLARITY_HiToLo << GPIOTE_CONFIG_POLARITY_Pos |
                                    PIN << GPIOTE_CONFIG_PSEL_Pos |
                                    GPIOTE_CONFIG_OUTINIT_High << GPIOTE_CONFIG_MODE_Pos;

NRF_TIMER3->BITMODE = TIMER_BITMODE_BITMODE_32Bit << TIMER_BITMODE_BITMODE_Pos;
NRF_TIMER3->PRESCALER = 0;
NRF_TIMER3->SHORTS = TIMER_SHORTS_COMPARE0_CLEAR_Enabled << 0;
NRF_TIMER3->MODE = TIMER_MODE_MODE_Counter << TIMER_MODE_MODE_Pos;
NRF_TIMER3->CC[0] = COUNT_LIMIT;
NRF_TIMER3->TASKS_START = 1;

NRF_PPI->CH[PPI_CH_0].EEP = (uint32_t)&NRF_GPIOTE->EVENTS_IN[GPIOTE_CH_IN];
NRF_PPI->CH[PPI_CH_0].TEP = (uint32_t)&NRF_TIMER3->TASKS_COUNT;