Merge pull request #129 from jsuiker/feature/dht-sensors
Added DHT library to extras and sample code to examples
This commit is contained in:
commit
11ec316038
5 changed files with 221 additions and 0 deletions
4
examples/dht_sensor/Makefile
Normal file
4
examples/dht_sensor/Makefile
Normal file
|
@ -0,0 +1,4 @@
|
|||
PROGRAM=dht_sensor
|
||||
EXTRA_COMPONENTS = extras/dht
|
||||
include ../../common.mk
|
||||
|
46
examples/dht_sensor/dht_sensor.c
Normal file
46
examples/dht_sensor/dht_sensor.c
Normal file
|
@ -0,0 +1,46 @@
|
|||
/*
|
||||
*
|
||||
* This sample code is in the public domain.
|
||||
*/
|
||||
#include "espressif/esp_common.h"
|
||||
#include "esp/uart.h"
|
||||
#include "FreeRTOS.h"
|
||||
#include "task.h"
|
||||
#include "dht.h"
|
||||
#include "esp8266.h"
|
||||
|
||||
/* An example using the ubiquitous DHT** humidity sensors
|
||||
* to read and print a new temperature and humidity measurement
|
||||
* from a sensor attached to GPIO pin 4.
|
||||
*/
|
||||
int const dht_gpio = 4;
|
||||
|
||||
void dhtMeasurementTask(void *pvParameters)
|
||||
{
|
||||
int8_t temperature = 0;
|
||||
int8_t humidity = 0;
|
||||
|
||||
// DHT sensors that come mounted on a PCB generally have
|
||||
// pull-up resistors on the data pin. It is recommended
|
||||
// to provide an external pull-up resistor otherwise...
|
||||
gpio_set_pullup(dht_gpio, false, false);
|
||||
|
||||
while(1) {
|
||||
|
||||
if (dht_fetch_data(dht_gpio, &humidity, &temperature)) {
|
||||
printf("Humidity: %i%% Temp: %iC\n", humidity, temperature);
|
||||
} else {
|
||||
printf("Could not read data from sensor...");
|
||||
}
|
||||
|
||||
// Three second delay...
|
||||
vTaskDelay(3000 / portTICK_RATE_MS);
|
||||
}
|
||||
}
|
||||
|
||||
void user_init(void)
|
||||
{
|
||||
uart_set_baud(0, 115200);
|
||||
xTaskCreate(dhtMeasurementTask, (signed char *)"dhtMeasurementTask", 256, NULL, 2, NULL);
|
||||
}
|
||||
|
10
extras/dht/component.mk
Normal file
10
extras/dht/component.mk
Normal file
|
@ -0,0 +1,10 @@
|
|||
# Component makefile for extras/dht
|
||||
|
||||
INC_DIRS += $(ROOT)extras/dht
|
||||
|
||||
# args for passing into compile rule generation
|
||||
extras/dht_INC_DIR = $(ROOT)extras/dht
|
||||
extras/dht_SRC_DIR = $(ROOT)extras/dht
|
||||
|
||||
$(eval $(call component_compile_rules,extras/dht))
|
||||
|
144
extras/dht/dht.c
Normal file
144
extras/dht/dht.c
Normal file
|
@ -0,0 +1,144 @@
|
|||
/*
|
||||
* Part of esp-open-rtos
|
||||
* Copyright (C) 2016 Jonathan Hartsuiker (https://github.com/jsuiker)
|
||||
* BSD Licensed as described in the file LICENSE
|
||||
*
|
||||
*/
|
||||
|
||||
#include "dht.h"
|
||||
#include "string.h"
|
||||
#include "task.h"
|
||||
#include "esp/gpio.h"
|
||||
|
||||
#include <espressif/esp_misc.h> // sdk_os_delay_us
|
||||
|
||||
#ifndef DEBUG_DHT
|
||||
#define DEBUG_DHT 0
|
||||
#endif
|
||||
|
||||
#if DEBUG_DHT
|
||||
#define debug(fmt, ...) printf("%s" fmt "\n", "dht: ", ## __VA_ARGS__);
|
||||
#else
|
||||
#define debug(fmt, ...) /* (do nothing) */
|
||||
#endif
|
||||
|
||||
/*
|
||||
* Note:
|
||||
* A suitable pull-up resistor should be connected to the selected GPIO line
|
||||
*
|
||||
* __ ______ _______ ___________________________
|
||||
* \ A / \ C / \ DHT duration_data_low / \
|
||||
* \_______/ B \______/ D \__________________________/ DHT duration_data_high \__
|
||||
*
|
||||
*
|
||||
* Initializing communications with the DHT requires four 'phases' as follows:
|
||||
*
|
||||
* Phase A - MCU pulls signal low for at least 18000 us
|
||||
* Phase B - MCU allows signal to float back up and waits 20-40us for DHT to pull it low
|
||||
* Phase C - DHT pulls signal low for ~80us
|
||||
* Phase D - DHT lets signal float back up for ~80us
|
||||
*
|
||||
* After this, the DHT transmits its first bit by holding the signal low for 50us
|
||||
* and then letting it float back high for a period of time that depends on the data bit.
|
||||
* duration_data_high is shorter than 50us for a logic '0' and longer than 50us for logic '1'.
|
||||
*
|
||||
* There are a total of 40 data bits trasnmitted sequentially. These bits are read into a byte array
|
||||
* of length 5. The first and third bytes are humidity (%) and temperature (C), respectively. Bytes 2 and 4
|
||||
* are zero-filled and the fifth is a checksum such that:
|
||||
*
|
||||
* byte_5 == (byte_1 + byte_2 + byte_3 + btye_4) & 0xFF
|
||||
*
|
||||
*/
|
||||
|
||||
/*
|
||||
* @pin the selected GPIO pin
|
||||
* @interval how frequently the pin state is checked in microseconds
|
||||
* @timeout maximum length of time to wait for the expected pin state
|
||||
* @expected_pin_state high (true) or low (false) pin state
|
||||
* @counter pointer to external uint8_t for tallying the duration waited for the pin state
|
||||
*/
|
||||
|
||||
bool dht_await_pin_state(uint8_t pin, uint8_t interval, uint8_t timeout, bool expected_pin_state, uint8_t * counter) {
|
||||
|
||||
for (*counter = 0; *counter < timeout; *counter+=interval) {
|
||||
if (gpio_read(pin) == expected_pin_state) return true;
|
||||
sdk_os_delay_us(interval);
|
||||
}
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
/*
|
||||
*
|
||||
*
|
||||
* @pin the selected GPIO pin
|
||||
* @humidity pointer to external int8_t to store resulting humidity value
|
||||
* @temperature pointer to external int8_t to store resulting temperature value
|
||||
*/
|
||||
|
||||
bool dht_fetch_data(int8_t pin, int8_t * humidity, int8_t * temperature) {
|
||||
int8_t data[40] = {0};
|
||||
int8_t result[5] = {0};
|
||||
uint8_t i = 0;
|
||||
|
||||
uint8_t init_phase_duration = 0;
|
||||
uint8_t duration_data_low = 0;
|
||||
uint8_t duration_data_high = 0;
|
||||
|
||||
gpio_enable(pin, GPIO_OUT_OPEN_DRAIN);
|
||||
|
||||
taskENTER_CRITICAL();
|
||||
|
||||
// Phase 'A' pulling signal low to initiate read sequence
|
||||
gpio_write(pin, 0);
|
||||
sdk_os_delay_us(20000);
|
||||
gpio_write(pin, 1);
|
||||
|
||||
// Step through Phase 'B' at 2us intervals, 40us max
|
||||
if (dht_await_pin_state(pin, 2, 40, false, &init_phase_duration)) {
|
||||
// Step through Phase 'C ' at 2us intervals, 88us max
|
||||
if (dht_await_pin_state(pin, 2, 88, true, &init_phase_duration)) {
|
||||
// Step through Phase 'D' at 2us intervals, 88us max
|
||||
if (dht_await_pin_state(pin, 2, 88, false, &init_phase_duration)) {
|
||||
|
||||
// Read in each of the 40 bits of data...
|
||||
for (i = 0; i < 40; i++) {
|
||||
if (dht_await_pin_state(pin, 2, 60, true, &duration_data_low)) {
|
||||
if (dht_await_pin_state(pin, 2, 75, false, &duration_data_high)) {
|
||||
data[i] = duration_data_high > duration_data_low;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
taskEXIT_CRITICAL();
|
||||
|
||||
for (i = 0; i < 40; i++) {
|
||||
// Read each bit into 'result' byte array...
|
||||
result[i/8] <<= 1;
|
||||
result[i/8] |= data[i];
|
||||
}
|
||||
|
||||
if (result[4] == ((result[0] + result[1] + result[2] + result[3]) & 0xFF)) {
|
||||
// Data valid, checksum succeeded...
|
||||
*humidity = result[0];
|
||||
*temperature = result[2];
|
||||
debug("Successfully retrieved sensor data...");
|
||||
return true;
|
||||
} else {
|
||||
debug("Checksum failed, invalid data received from sensor...");
|
||||
}
|
||||
|
||||
} else {
|
||||
debug("Initialization error, problem in phase 'D'...");
|
||||
}
|
||||
} else {
|
||||
debug("Initialization error, problem in phase 'C'...");
|
||||
}
|
||||
} else {
|
||||
debug("Initialization error, problem in phase 'B'...");
|
||||
}
|
||||
|
||||
taskEXIT_CRITICAL();
|
||||
return false;
|
||||
}
|
||||
|
17
extras/dht/dht.h
Normal file
17
extras/dht/dht.h
Normal file
|
@ -0,0 +1,17 @@
|
|||
/*
|
||||
* Part of esp-open-rtos
|
||||
* Copyright (C) 2016 Jonathan Hartsuiker (https://github.com/jsuiker)
|
||||
* BSD Licensed as described in the file LICENSE
|
||||
*
|
||||
*/
|
||||
|
||||
#ifndef __DTH_H__
|
||||
#define __DHT_H__
|
||||
|
||||
#include "FreeRTOS.h"
|
||||
|
||||
bool dht_wait_for_pin_state(uint8_t pin, uint8_t interval, uint8_t timeout, bool expected_pin_sate, uint8_t * counter);
|
||||
bool dht_fetch_data(int8_t pin, int8_t * humidity, int8_t * temperature);
|
||||
|
||||
#endif
|
||||
|
Loading…
Reference in a new issue