mirror of
https://github.com/RIOT-OS/RIOT.git
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145 lines
3.5 KiB
C
145 lines
3.5 KiB
C
/*
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* Copyright (C) 2020 Locha Inc
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup drivers_gp2y10xx
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* @{
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*
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* @file
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* @brief GP2Y10xx Compact Optical Dust Sensor device driver
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*
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* @author Jean Pierre Dudey <jeandudey@hotmail.com>
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* @}
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*/
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#include <assert.h>
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#include "gp2y10xx.h"
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#include "gp2y10xx_params.h"
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#include "periph/adc.h"
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#include "periph/gpio.h"
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#include "xtimer.h"
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#define ENABLE_DEBUG 0
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#include "debug.h"
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#define ILED_PULSE_WAIT_US (280U)
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#define ILED_PULSE_OFF_US (20U)
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#define NO_DUST_VOLTAGE (500)
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static inline void _iled_on(const gp2y10xx_t *dev)
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{
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gpio_write(dev->params.iled_pin,
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dev->params.iled_level == GP2Y10XX_ILED_LEVEL_HIGH);
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}
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static inline void _iled_off(const gp2y10xx_t *dev)
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{
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gpio_write(dev->params.iled_pin,
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dev->params.iled_level == GP2Y10XX_ILED_LEVEL_LOW);
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}
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static inline int _adc_resolution(adc_res_t res)
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{
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/* get the resolution the ADC can read */
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int exp = 0;
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switch (res) {
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case ADC_RES_6BIT:
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exp = 6;
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break;
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case ADC_RES_8BIT:
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exp = 8;
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break;
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case ADC_RES_10BIT:
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exp = 10;
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break;
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case ADC_RES_12BIT:
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exp = 12;
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break;
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case ADC_RES_14BIT:
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exp = 14;
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break;
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case ADC_RES_16BIT:
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exp = 16;
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break;
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default:
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assert(0);
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break;
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}
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return exp;
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}
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int gp2y10xx_init(gp2y10xx_t *dev, const gp2y10xx_params_t *params)
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{
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assert(dev && params);
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dev->params = *params;
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if (adc_init(dev->params.aout) < 0) {
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return GP2Y10XX_ERR_ADC;
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}
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if (gpio_init(dev->params.iled_pin, GPIO_OUT) < 0) {
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return GP2Y10XX_ERR_ILED;
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}
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_iled_off(dev);
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return GP2Y10XX_OK;
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}
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int gp2y10xx_read_density(const gp2y10xx_t *dev, uint16_t *density)
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{
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uint32_t adc_sum = 0;
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int32_t adc_value;
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uint32_t voltage;
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assert(dev && density);
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for (unsigned i = 0; i < CONFIG_GP2Y10XX_MAX_READINGS; i++) {
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/* turn ILED on/off and wait a little bit to read the ADC */
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_iled_on(dev);
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xtimer_usleep(ILED_PULSE_WAIT_US);
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if ((adc_value = adc_sample(dev->params.aout,
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dev->params.adc_res)) < 0) {
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_iled_off(dev);
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return GP2Y10XX_ERR_ADC;
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}
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_iled_off(dev);
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xtimer_usleep(ILED_PULSE_OFF_US);
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DEBUG("[gp2y10xx] read: unfiltered adc_value=%"PRIi32"\n", adc_value);
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adc_sum += adc_value;
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}
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/* calculate the average between all readings */
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adc_value = adc_sum / CONFIG_GP2Y10XX_MAX_READINGS;
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DEBUG("[gp2y10xx] read: filtered adc_value=%"PRIi32"\n", adc_value);
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/* convert ADC reading to a voltage */
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voltage = (dev->params.vref * adc_value);
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voltage >>= _adc_resolution(dev->params.adc_res);
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/* check if the voltage provides us meaningful data */
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if (voltage <= NO_DUST_VOLTAGE) {
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*density = 0;
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}
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else {
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voltage -= NO_DUST_VOLTAGE;
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}
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DEBUG("[gp2y10xx] read: voltage=%"PRIi32"\n", voltage);
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/* multiply by the magic eleven.
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*
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* XXX: find out why 11 is magic and the shenanigans behind it
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*/
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voltage *= 11;
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/* convert "voltage" to ug/m3 */
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*density = (uint16_t)((voltage * 2) / 10);
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return GP2Y10XX_OK;
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}
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