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

122 lines
4.5 KiB

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2019 Dan Halbert for Adafruit Industries
* 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 "py/runtime.h"
#include "supervisor/shared/translate.h"
#include "nrf_saadc.h"
#include "nrf_gpio.h"
#define CHANNEL_NO 0
void analogin_init(void) {
// Calibrate the ADC once, on startup.
nrf_saadc_enable(NRF_SAADC);
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_CALIBRATEDONE);
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_CALIBRATEOFFSET);
while (nrf_saadc_event_check(NRF_SAADC, NRF_SAADC_EVENT_CALIBRATEDONE) == 0) { }
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_CALIBRATEDONE);
nrf_saadc_disable(NRF_SAADC);
}
void common_hal_analogio_analogin_construct(analogio_analogin_obj_t *self, const mcu_pin_obj_t *pin) {
if (pin->adc_channel == 0)
mp_raise_ValueError(translate("Pin does not have ADC capabilities"));
nrf_gpio_cfg_default(pin->number);
claim_pin(pin);
self->pin = pin;
}
bool common_hal_analogio_analogin_deinited(analogio_analogin_obj_t *self) {
return self->pin == NULL;
}
void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
if (common_hal_analogio_analogin_deinited(self))
return;
nrf_gpio_cfg_default(self->pin->number);
reset_pin_number(self->pin->number);
self->pin = NULL;
}
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.
nrf_saadc_value_t value;
const nrf_saadc_channel_config_t config = {
.resistor_p = NRF_SAADC_RESISTOR_DISABLED,
.resistor_n = NRF_SAADC_RESISTOR_DISABLED,
.gain = NRF_SAADC_GAIN1_4,
.reference = NRF_SAADC_REFERENCE_VDD4,
.acq_time = NRF_SAADC_ACQTIME_3US,
.mode = NRF_SAADC_MODE_SINGLE_ENDED,
.burst = NRF_SAADC_BURST_DISABLED
};
nrf_saadc_resolution_set(NRF_SAADC, NRF_SAADC_RESOLUTION_14BIT);
nrf_saadc_oversample_set(NRF_SAADC, NRF_SAADC_OVERSAMPLE_DISABLED);
nrf_saadc_enable(NRF_SAADC);
for (uint32_t i = 0; i < SAADC_CH_NUM; i++)
nrf_saadc_channel_input_set(NRF_SAADC, i, NRF_SAADC_INPUT_DISABLED, NRF_SAADC_INPUT_DISABLED);
nrf_saadc_channel_init(NRF_SAADC, CHANNEL_NO, &config);
nrf_saadc_channel_input_set(NRF_SAADC, CHANNEL_NO, self->pin->adc_channel, self->pin->adc_channel);
nrf_saadc_buffer_init(NRF_SAADC, &value, 1);
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_START);
while (nrf_saadc_event_check(NRF_SAADC, NRF_SAADC_EVENT_STARTED) == 0);
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_STARTED);
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_SAMPLE);
while (nrf_saadc_event_check(NRF_SAADC, NRF_SAADC_EVENT_END) == 0);
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_END);
nrf_saadc_task_trigger(NRF_SAADC, NRF_SAADC_TASK_STOP);
while (nrf_saadc_event_check(NRF_SAADC, NRF_SAADC_EVENT_STOPPED) == 0);
nrf_saadc_event_clear(NRF_SAADC, NRF_SAADC_EVENT_STOPPED);
nrf_saadc_disable(NRF_SAADC);
if (value < 0)
value = 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) {
// The nominal VCC voltage
return 3.3f;
}