circuitpython/ports/nrf/common-hal/analogio/AnalogIn.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "common-hal/analogio/AnalogIn.h"

#include <string.h>

#include "py/gc.h"
#include "py/nlr.h"
#include "py/runtime.h"
#include "py/binary.h"
#include "py/mphal.h"
#include "shared-bindings/analogio/AnalogIn.h"
#include "nrf.h"

void common_hal_analogio_analogin_construct(analogio_analogin_obj_t* self, const mcu_pin_obj_t *pin) {
    if (!pin->adc_channel) {
        // No ADC function on that pin
        mp_raise_ValueError("Pin does not have ADC capabilities");
    }

    hal_gpio_cfg_pin(pin->port, pin->pin, HAL_GPIO_MODE_INPUT, HAL_GPIO_PULL_DISABLED);
    self->pin = pin;
}

bool common_hal_analogio_analogin_deinited(analogio_analogin_obj_t *self) {
    return self->pin == mp_const_none;
}

void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
    if (common_hal_analogio_analogin_deinited(self)) {
        return;
    }
    reset_pin(self->pin->pin);
    self->pin = mp_const_none;
}

void analogin_reset() {
}

uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
  // Something else might have used the ADC in a different way,
  // so we completely re-initialize it.

  int16_t value;

  NRF_SAADC->RESOLUTION = SAADC_RESOLUTION_VAL_14bit;
  NRF_SAADC->ENABLE = 1;

  for (int i = 0; i < 8; i++) {
    NRF_SAADC->CH[i].PSELN = SAADC_CH_PSELP_PSELP_NC;
    NRF_SAADC->CH[i].PSELP = SAADC_CH_PSELP_PSELP_NC;
  }

  NRF_SAADC->CH[0].CONFIG = ((SAADC_CH_CONFIG_RESP_Bypass       << SAADC_CH_CONFIG_RESP_Pos)   & SAADC_CH_CONFIG_RESP_Msk)
                            | ((SAADC_CH_CONFIG_RESP_Bypass     << SAADC_CH_CONFIG_RESN_Pos)   & SAADC_CH_CONFIG_RESN_Msk)
                            | ((SAADC_CH_CONFIG_GAIN_Gain1_6    << 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_3us        << SAADC_CH_CONFIG_TACQ_Pos)   & SAADC_CH_CONFIG_TACQ_Msk)
                            | ((SAADC_CH_CONFIG_MODE_SE         << SAADC_CH_CONFIG_MODE_Pos)   & SAADC_CH_CONFIG_MODE_Msk);
  NRF_SAADC->CH[0].PSELN = self->pin->adc_channel;
  NRF_SAADC->CH[0].PSELP = self->pin->adc_channel;


  NRF_SAADC->RESULT.PTR = (uint32_t)&value;
  NRF_SAADC->RESULT.MAXCNT = 1;

  NRF_SAADC->TASKS_START = 0x01UL;

  while (!NRF_SAADC->EVENTS_STARTED);
  NRF_SAADC->EVENTS_STARTED = 0x00UL;

  NRF_SAADC->TASKS_SAMPLE = 0x01UL;

  while (!NRF_SAADC->EVENTS_END);
  NRF_SAADC->EVENTS_END = 0x00UL;

  NRF_SAADC->TASKS_STOP = 0x01UL;

  while (!NRF_SAADC->EVENTS_STOPPED);
  NRF_SAADC->EVENTS_STOPPED = 0x00UL;

  if (value < 0) {
    value = 0;
  }

  NRF_SAADC->ENABLE = 0;

  // Map value to from 14 to 16 bits
  return (value << 2);
}

float common_hal_analogio_analogin_get_reference_voltage(analogio_analogin_obj_t *self) {
    return 3.3f;
}