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81 lines
1.9 KiB
C
81 lines
1.9 KiB
C
/*
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* Copyright (C) 2016 Freie Universität Berlin
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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_dht
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* @{
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*
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* @file
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* @brief SAUL adaption for DHT devices
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*
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* The values exported to SAUL for DHT devices are buffered, meaning that new
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* values will only be read from the device, if the buffered values are older
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* then 1 second (being exactly the maximum sampling time for DHT devices).
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*
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* This buffering does further introduce a coupling between both SAUL endpoints,
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* meaning that if you read from both endpoints after each other, both values
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* are from the same sensor reading.
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*
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*
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* @}
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*/
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#include <string.h>
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#include "saul.h"
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#include "dht.h"
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#include "xtimer.h"
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#define DHT_SAUL_HOLD_TIME (1000 * 1000U) /* 1s */
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static int16_t temp, hum;
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static uint32_t last = 0;
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static int check_and_read(void *dev, phydat_t *res, int16_t *val, uint8_t unit)
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{
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dht_t *d = (dht_t *)dev;
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uint32_t now = xtimer_now();
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if ((now - last) > DHT_SAUL_HOLD_TIME) {
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dht_read(d, &temp, &hum);
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last = now;
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}
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else {
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(void)d;
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}
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res->val[0] = *val;
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memset(&res->val[1], 0, 2 * sizeof(int16_t));
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res->unit = unit;
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res->scale = -1;
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return 1;
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}
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static int read_temp(void *dev, phydat_t *res)
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{
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return check_and_read(dev, res, &temp, UNIT_TEMP_C);
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}
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static int read_hum(void *dev, phydat_t *res)
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{
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return check_and_read(dev, res, &hum, UNIT_PERCENT);
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}
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const saul_driver_t dht_temp_saul_driver = {
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.read = read_temp,
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.write = saul_notsup,
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.type = SAUL_SENSE_TEMP
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};
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const saul_driver_t dht_hum_saul_driver = {
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.read = read_hum,
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.write = saul_notsup,
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.type = SAUL_SENSE_HUM
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};
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