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Copyright (c) 2015, SuperHouse Automation Pty Ltd
Copyright (c) 2016, Jonathan Hartsuiker (https://github.com/jsuiker)
Copyright (c) 2019, Fonger (https://github.com/fonger)
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <driver/gpio.h>
#include <esp8266/gpio_struct.h>
#include <rom/ets_sys.h>
#include <esp_log.h>
#include "dht.h"
#define DHT_PIN GPIO_NUM_2
#define DHT_DATA_LEN 40
static const char *tag = "dht";
static inline int dht_get_pin_state()
{
return (GPIO.in >> DHT_PIN) & 0x1;
}
static inline int dht_await_pin_state(int state, int timeout)
{
int t;
static const uint16_t delta = 1;
for (t = 0; t < timeout; t += delta) {
os_delay_us(delta);
if (dht_get_pin_state() == state)
return t;
}
return 0;
}
static inline int dht_get_raw_data(uint8_t buf[DHT_DATA_LEN])
{
uint8_t i, pwl, pwh;
gpio_set_level(DHT_PIN, 0);
os_delay_us(1100);
gpio_set_level(DHT_PIN, 1);
if (!dht_await_pin_state(0, 40)) {
ESP_LOGI(tag, "start sequence phase 1 error");
return 0;
}
if (!dht_await_pin_state(1, 80)) {
ESP_LOGI(tag, "start sequence phase 2 error");
return 0;
}
if (!dht_await_pin_state(0, 80)) {
ESP_LOGI(tag, "start sequence phase 3 error");
return 0;
}
for (i = 0; i < DHT_DATA_LEN; i++) {
if (!(pwl = dht_await_pin_state(1, 50))) {
ESP_LOGI(tag, "low bit timed out");
return 0;
}
if (!(pwh = dht_await_pin_state(0, 70))) {
ESP_LOGI(tag, "high bit timed out");
return 0;
}
buf[i] = pwh > pwl;
}
return 1;
}
static inline int dht_verify_checksum(const uint8_t data[5])
{
return data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF);
}
int16_t dht_decode_data(uint8_t msb, uint8_t lsb)
{
int16_t x;
x = msb & 0x7F;
x <<= 8;
x |= lsb;
if (msb >> 7)
x = 0 - x;
return x;
}
int dht_get_data(uint8_t result[5])
{
uint8_t i, rc, buf[DHT_DATA_LEN];
vPortETSIntrLock();
rc = dht_get_raw_data(buf);
vPortETSIntrUnlock();
if (rc) {
for (i = 0; i < DHT_DATA_LEN; i++) {
result[i / 8] <<= 1;
result[i / 8] |= buf[i];
}
if (dht_verify_checksum(result))
return 1;
else
ESP_LOGI(tag, "checksum failed");
}
return 0;
}
void dht_init(void)
{
gpio_config_t io_conf;
io_conf.pin_bit_mask = 1UL << DHT_PIN;
io_conf.mode = GPIO_MODE_OUTPUT_OD;
gpio_config(&io_conf);
gpio_set_level(DHT_PIN, 1);
vTaskDelay(1000 / portTICK_PERIOD_MS);
}
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