pir_sense.c

#include "pir_sense.h"
#include "nrf.h"
#include "common_util.h"
#include "nrf_util.h"

#if ISR_MANAGER == 1
#include "isr_manager.h"
#endif

#define PIR_SENSE_RTC_USED           RTC_USED_PIR_SENSE

#define SAADC_CHANNEL                SAADC_CHANNEL_USED_PIR_SENSE

#define RTC_ID                       CONCAT_2(NRF_RTC,RTC_USED_PIR_SENSE)

static int16_t saadc_result[1];

void (*sense_handler)(int32_t adc_val);

#if ISR_MANAGER == 1
void pir_sense_saadc_Handler (void)
#else
void SAADC_IRQHandler(void)
#endif
{
#if ISR_MANAGER == 0
    NRF_SAADC->EVENTS_CH[SAADC_CHANNEL].LIMITH = 0;
    (void) NRF_SAADC->EVENTS_CH[SAADC_CHANNEL].LIMITH;
    NRF_SAADC->EVENTS_CH[SAADC_CHANNEL].LIMITL = 0;
    (void) NRF_SAADC->EVENTS_CH[SAADC_CHANNEL].LIMITL;
#endif
    sense_handler(saadc_result[0]);
}

void pir_sense_start(pir_sense_cfg * init)
{
    //Set the handler to be called
    sense_handler = init->handler;

    //ADC config: 12 bit, no oversampling, differential inputs, 10 us sampling,
    //no burst mode, 1.2V internal reference
    NRF_SAADC->RESOLUTION = SAADC_RESOLUTION_VAL_12bit << SAADC_RESOLUTION_VAL_Pos;
    NRF_SAADC->OVERSAMPLE = SAADC_OVERSAMPLE_OVERSAMPLE_Bypass;
    NRF_SAADC->SAMPLERATE = (0 << SAADC_SAMPLERATE_CC_Pos) |
                (SAADC_SAMPLERATE_MODE_Task << SAADC_SAMPLERATE_MODE_Pos);
    NRF_SAADC->RESULT.PTR = (uint32_t)saadc_result;
    NRF_SAADC->RESULT.MAXCNT = ARRAY_SIZE(saadc_result);
    NRF_SAADC->CH[SAADC_CHANNEL].PSELN = init->pir_offset_analog_in;
    NRF_SAADC->CH[SAADC_CHANNEL].PSELP = init->pir_signal_analog_in;

    NRF_SAADC->CH[SAADC_CHANNEL].CONFIG =
                ((SAADC_CH_CONFIG_RESP_Bypass        << SAADC_CH_CONFIG_RESP_Pos)   & SAADC_CH_CONFIG_RESP_Msk)
                | ((SAADC_CH_CONFIG_RESN_Bypass      << SAADC_CH_CONFIG_RESN_Pos)   & SAADC_CH_CONFIG_RESN_Msk)
                | ((SAADC_CH_CONFIG_GAIN_Gain1       << SAADC_CH_CONFIG_GAIN_Pos)   & SAADC_CH_CONFIG_GAIN_Msk)
                | ((SAADC_CH_CONFIG_REFSEL_Internal  << SAADC_CH_CONFIG_REFSEL_Pos) & SAADC_CH_CONFIG_REFSEL_Msk)
                | ((SAADC_CH_CONFIG_TACQ_40us        << SAADC_CH_CONFIG_TACQ_Pos)   & SAADC_CH_CONFIG_TACQ_Msk)
                | ((SAADC_CH_CONFIG_MODE_Diff        << SAADC_CH_CONFIG_MODE_Pos)   & SAADC_CH_CONFIG_MODE_Msk)
                | ((SAADC_CH_CONFIG_BURST_Disabled   << SAADC_CH_CONFIG_BURST_Pos)  & SAADC_CH_CONFIG_BURST_Msk);

    NRF_SAADC->CH[SAADC_CHANNEL].LIMIT = (
                (((-1*((int16_t) init->threshold)) << SAADC_CH_LIMIT_LOW_Pos) & SAADC_CH_LIMIT_LOW_Msk)
              | (((uint16_t) init->threshold << SAADC_CH_LIMIT_HIGH_Pos) & SAADC_CH_LIMIT_HIGH_Msk));

    NVIC_SetPriority(SAADC_IRQn, init->irq_priority);
    NVIC_EnableIRQ(SAADC_IRQn);
    NVIC_ClearPendingIRQ(SAADC_IRQn);

    NRF_SAADC->INTENCLR = 0xFFFFFFFF;
    NRF_SAADC->INTENSET = ((1 << (SAADC_CHANNEL*2 + 6)) | (1 << (SAADC_CHANNEL*2 + 7)));

    //On ADC start event, trigger the ADC sampling
    NRF_PPI->CH[PPI_CHANNEL_USED_PIR_SENSE_1].EEP = (uint32_t) &(NRF_SAADC->EVENTS_STARTED);
    NRF_PPI->CH[PPI_CHANNEL_USED_PIR_SENSE_1].TEP = (uint32_t) &(NRF_SAADC->TASKS_SAMPLE);

    //On RTC0 Compare0 event, trigger ADC start task and also clear the RTC0 counter
    NRF_PPI->CH[PPI_CHANNEL_USED_PIR_SENSE_2].EEP = (uint32_t) &(RTC_ID->EVENTS_COMPARE[0]);
    NRF_PPI->CH[PPI_CHANNEL_USED_PIR_SENSE_2].TEP = (uint32_t) &(NRF_SAADC->TASKS_START);
    NRF_PPI->FORK[PPI_CHANNEL_USED_PIR_SENSE_2].TEP = (uint32_t) &(RTC_ID->TASKS_CLEAR);

    //On ADC end event, stop the ADC to disable it and save power
    NRF_PPI->CH[PPI_CHANNEL_USED_PIR_SENSE_3].EEP = (uint32_t) &(NRF_SAADC->EVENTS_END);
    NRF_PPI->CH[PPI_CHANNEL_USED_PIR_SENSE_3].TEP = (uint32_t) &(NRF_SAADC->TASKS_STOP);

    //Enable the above three PPIs
    NRF_PPI->CHENSET = (1 << PPI_CHANNEL_USED_PIR_SENSE_1) |
            (1 << PPI_CHANNEL_USED_PIR_SENSE_2) |
            (1 << PPI_CHANNEL_USED_PIR_SENSE_3);

    //Start off the ADC with CC0 as the sensing interval
    RTC_ID->TASKS_STOP = 1;
    RTC_ID->PRESCALER = 0;
    RTC_ID->CC[0] = LFCLK_TICKS_MS(init->sense_interval_ms);
    RTC_ID->EVTENSET = (RTC_EVTENSET_COMPARE0_Enabled << RTC_EVTENSET_COMPARE0_Pos);
    RTC_ID->EVENTS_COMPARE[0] = 0;
    RTC_ID->TASKS_START = 1;

    NRF_SAADC->ENABLE = (SAADC_ENABLE_ENABLE_Enabled << SAADC_ENABLE_ENABLE_Pos);
}

void pir_sense_stop(void)
{
    NRF_SAADC->ENABLE = (SAADC_ENABLE_ENABLE_Disabled << SAADC_ENABLE_ENABLE_Pos);
    NVIC_DisableIRQ(SAADC_IRQn);

    NRF_SAADC->INTENCLR = 0xFFFFFFFF;
    NRF_SAADC->CH[SAADC_CHANNEL].PSELP = SAADC_CH_PSELP_PSELP_NC;

    NRF_PPI->CHENCLR = (PPI_CHENCLR_CH0_Clear << PPI_CHANNEL_USED_PIR_SENSE_1) |
                (PPI_CHENCLR_CH1_Clear << PPI_CHANNEL_USED_PIR_SENSE_2) |
                (PPI_CHENCLR_CH2_Clear << PPI_CHANNEL_USED_PIR_SENSE_3);

    RTC_ID->TASKS_CLEAR = 1;
    RTC_ID->TASKS_STOP = 1;
}