DHT11/22 library fix
Support DHT11/DHT22 modules. Data representation fix. Library refactoring.
This commit is contained in:
sheinz
parent
78c5b43a40
commit
a41407e3d1
3 changed files with 181 additions and 106 deletions
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@ -2,6 +2,8 @@
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*
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* This sample code is in the public domain.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "espressif/esp_common.h"
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#include "esp/uart.h"
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#include "FreeRTOS.h"
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@ -13,12 +15,12 @@
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* to read and print a new temperature and humidity measurement
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* from a sensor attached to GPIO pin 4.
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*/
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int const dht_gpio = 4;
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uint8_t const dht_gpio = 12;
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void dhtMeasurementTask(void *pvParameters)
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{
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int8_t temperature = 0;
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int8_t humidity = 0;
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int16_t temperature = 0;
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int16_t humidity = 0;
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// DHT sensors that come mounted on a PCB generally have
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// pull-up resistors on the data pin. It is recommended
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@ -26,11 +28,12 @@ void dhtMeasurementTask(void *pvParameters)
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gpio_set_pullup(dht_gpio, false, false);
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while(1) {
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if (dht_fetch_data(dht_gpio, &humidity, &temperature)) {
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printf("Humidity: %i%% Temp: %iC\n", humidity, temperature);
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if (dht_read_data(dht_gpio, &humidity, &temperature)) {
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printf("Humidity: %d.%d%% Temp: %d.%dC\n",
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humidity / 10, humidity % 10,
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temperature / 10, abs(temperature) % 10);
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} else {
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printf("Could not read data from sensor...");
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printf("Could not read data from sensor\n");
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}
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// Three second delay...
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213
extras/dht/dht.c
213
extras/dht/dht.c
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@ -6,17 +6,20 @@
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*/
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#include "dht.h"
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#include "FreeRTOS.h"
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#include "string.h"
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#include "task.h"
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#include "esp/gpio.h"
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#include <espressif/esp_misc.h> // sdk_os_delay_us
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#ifndef DEBUG_DHT
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#define DEBUG_DHT 0
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#endif
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// DHT timer precision in microseconds
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#define DHT_TIMER_INTERVAL 2
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#define DHT_DATA_BITS 40
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#if DEBUG_DHT
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// #define DEBUG_DHT
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#ifdef DEBUG_DHT
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#define debug(fmt, ...) printf("%s" fmt "\n", "dht: ", ## __VA_ARGS__);
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#else
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#define debug(fmt, ...) /* (do nothing) */
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@ -42,7 +45,7 @@
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* and then letting it float back high for a period of time that depends on the data bit.
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* duration_data_high is shorter than 50us for a logic '0' and longer than 50us for logic '1'.
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*
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* There are a total of 40 data bits trasnmitted sequentially. These bits are read into a byte array
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* There are a total of 40 data bits transmitted sequentially. These bits are read into a byte array
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* of length 5. The first and third bytes are humidity (%) and temperature (C), respectively. Bytes 2 and 4
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* are zero-filled and the fifth is a checksum such that:
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*
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@ -50,95 +53,143 @@
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*
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*/
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/*
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* @pin the selected GPIO pin
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* @interval how frequently the pin state is checked in microseconds
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* @timeout maximum length of time to wait for the expected pin state
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* @expected_pin_state high (true) or low (false) pin state
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* @counter pointer to external uint8_t for tallying the duration waited for the pin state
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/**
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* Wait specified time for pin to go to a specified state.
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* If timeout is reached and pin doesn't go to a requested state
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* false is returned.
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* The elapsed time is returned in pointer 'duration' if it is not NULL.
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*/
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bool dht_await_pin_state(uint8_t pin, uint8_t interval, uint8_t timeout, bool expected_pin_state, uint8_t * counter) {
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for (*counter = 0; *counter < timeout; *counter+=interval) {
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if (gpio_read(pin) == expected_pin_state) return true;
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sdk_os_delay_us(interval);
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static bool dht_await_pin_state(uint8_t pin, uint32_t timeout,
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bool expected_pin_state, uint32_t *duration)
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{
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for (uint32_t i = 0; i < timeout; i += DHT_TIMER_INTERVAL) {
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if (gpio_read(pin) == expected_pin_state) {
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if (duration) {
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*duration = i;
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}
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return true;
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}
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sdk_os_delay_us(DHT_TIMER_INTERVAL);
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}
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return false;
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}
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/*
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*
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*
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* @pin the selected GPIO pin
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* @humidity pointer to external int8_t to store resulting humidity value
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* @temperature pointer to external int8_t to store resulting temperature value
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/**
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* Request data from DHT and read raw bit stream.
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* The function call should be protected from task switching.
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* Return false if error occurred.
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*/
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bool dht_fetch_data(int8_t pin, int8_t * humidity, int8_t * temperature) {
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int8_t data[40] = {0};
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int8_t result[5] = {0};
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uint8_t i = 0;
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uint8_t init_phase_duration = 0;
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uint8_t duration_data_low = 0;
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uint8_t duration_data_high = 0;
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gpio_enable(pin, GPIO_OUT_OPEN_DRAIN);
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taskENTER_CRITICAL();
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static inline bool dht_fetch_data(uint8_t pin, bool bits[DHT_DATA_BITS])
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{
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uint32_t low_duration;
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uint32_t high_duration;
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// Phase 'A' pulling signal low to initiate read sequence
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gpio_write(pin, 0);
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sdk_os_delay_us(20000);
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gpio_write(pin, 1);
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// Step through Phase 'B' at 2us intervals, 40us max
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if (dht_await_pin_state(pin, 2, 40, false, &init_phase_duration)) {
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// Step through Phase 'C ' at 2us intervals, 88us max
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if (dht_await_pin_state(pin, 2, 88, true, &init_phase_duration)) {
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// Step through Phase 'D' at 2us intervals, 88us max
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if (dht_await_pin_state(pin, 2, 88, false, &init_phase_duration)) {
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// Read in each of the 40 bits of data...
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for (i = 0; i < 40; i++) {
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if (dht_await_pin_state(pin, 2, 60, true, &duration_data_low)) {
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if (dht_await_pin_state(pin, 2, 75, false, &duration_data_high)) {
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data[i] = duration_data_high > duration_data_low;
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}
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}
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}
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taskEXIT_CRITICAL();
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for (i = 0; i < 40; i++) {
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// Read each bit into 'result' byte array...
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result[i/8] <<= 1;
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result[i/8] |= data[i];
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}
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if (result[4] == ((result[0] + result[1] + result[2] + result[3]) & 0xFF)) {
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// Data valid, checksum succeeded...
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*humidity = result[0];
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*temperature = result[2];
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debug("Successfully retrieved sensor data...");
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return true;
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} else {
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debug("Checksum failed, invalid data received from sensor...");
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}
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} else {
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debug("Initialization error, problem in phase 'D'...");
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}
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} else {
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debug("Initialization error, problem in phase 'C'...");
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}
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} else {
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debug("Initialization error, problem in phase 'B'...");
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}
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taskEXIT_CRITICAL();
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// Step through Phase 'B', 40us
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if (!dht_await_pin_state(pin, 40, false, NULL)) {
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debug("Initialization error, problem in phase 'B'\n");
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return false;
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}
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// Step through Phase 'C', 88us
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if (!dht_await_pin_state(pin, 88, true, NULL)) {
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debug("Initialization error, problem in phase 'C'\n");
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return false;
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}
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// Step through Phase 'D', 88us
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if (!dht_await_pin_state(pin, 88, false, NULL)) {
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debug("Initialization error, problem in phase 'D'\n");
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return false;
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}
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// Read in each of the 40 bits of data...
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for (int i = 0; i < DHT_DATA_BITS; i++) {
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if (!dht_await_pin_state(pin, 65, true, &low_duration)) {
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debug("LOW bit timeout\n");
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return false;
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}
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if (!dht_await_pin_state(pin, 75, false, &high_duration)){
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debug("HIGHT bit timeout\n");
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return false;
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}
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bits[i] = high_duration > low_duration;
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}
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return true;
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}
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/**
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* Pack two data bytes into single value and take into account sign bit.
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*/
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static inline int16_t dht_convert_data(uint8_t msb, uint8_t lsb)
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{
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int16_t data;
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#if DHT_TYPE == DHT22
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data = msb & 0x7F;
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data <<= 8;
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data |= lsb;
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if (msb & BIT(15)) {
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data = 0 - data; // convert it to negative
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}
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#elif DHT_TYPE == DHT11
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data = msb * 10;
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#else
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#error "Unsupported DHT type"
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#endif
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return data;
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}
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bool dht_read_data(uint8_t pin, int16_t *humidity, int16_t *temperature)
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{
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bool bits[DHT_DATA_BITS];
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uint8_t data[DHT_DATA_BITS/8] = {0};
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bool result;
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gpio_enable(pin, GPIO_OUT_OPEN_DRAIN);
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taskENTER_CRITICAL();
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result = dht_fetch_data(pin, bits);
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taskEXIT_CRITICAL();
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if (!result) {
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return false;
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}
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for (uint8_t i = 0; i < DHT_DATA_BITS; i++) {
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// Read each bit into 'result' byte array...
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data[i/8] <<= 1;
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data[i/8] |= bits[i];
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}
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if (data[4] != (data[0] + data[1] + data[2] + data[3])) {
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debug("Checksum failed, invalid data received from sensor\n");
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return false;
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}
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*humidity = dht_convert_data(data[0], data[1]);
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*temperature = dht_convert_data(data[2], data[3]);
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debug("Sensor data: humidity=%d, temp=%d\n", *humidity, *temperature);
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return true;
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}
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bool dht_read_float_data(uint8_t pin, float *humidity, float *temperature)
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{
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int16_t i_humidity, i_temp;
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if (dht_read_data(pin, &i_humidity, &i_temp)) {
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*humidity = (float)i_humidity / 10;
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*temperature = (float)i_temp / 10;
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return true;
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}
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return false;
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}
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@ -5,13 +5,34 @@
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*
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*/
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#ifndef __DTH_H__
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#ifndef __DHT_H__
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#define __DHT_H__
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#include "FreeRTOS.h"
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#include <stdint.h>
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#include <stdbool.h>
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bool dht_wait_for_pin_state(uint8_t pin, uint8_t interval, uint8_t timeout, bool expected_pin_sate, uint8_t * counter);
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bool dht_fetch_data(int8_t pin, int8_t * humidity, int8_t * temperature);
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#define DHT11 11
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#define DHT22 22
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#endif
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// Type of sensor to use
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#define DHT_TYPE DHT22
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/**
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* Read data from sensor on specified pin.
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*
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* Humidity and temperature is returned as integers.
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* For example: humidity=625 is 62.5 %
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* temperature=24.4 is 24.4 degrees Celsius
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*
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*/
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bool dht_read_data(uint8_t pin, int16_t *humidity, int16_t *temperature);
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/**
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* Float version of dht_read_data.
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*
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* Return values as floating point values.
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*/
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bool dht_read_float_data(uint8_t pin, float *humidity, float *temperature);
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#endif // __DHT_H__
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