Arthur Roberts
6b40f97ba5
Need to keep debugging it... think of a different way to approach it maybe
111 lines
2.9 KiB
C
111 lines
2.9 KiB
C
#include "dht22.h"
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#include "esp_log.h"
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#include "hal/gpio_types.h"
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#include "sdkconfig.h"
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#include "driver/gpio.h"
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#include <rom/ets_sys.h>
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#include "esp_timer.h"
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#include "freertos/portmacro.h"
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#define DATA_GPIO CONFIG_DHT22_DATA_GPIO
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#if DATA_GPIO == -1
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#error "Please define your DHT22 GPIO Data Pin"
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#endif /* CONFIG_DHT22_DATA_GPIO == -1 */
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static const char *TAG = "DHT22";
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deci_percent _dht22_relative_humidity = UINT16_MAX;
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deci_degrees_c _dht22_temperature = INT16_MIN;
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void dht22_handle_error(dht22_error e) {
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if (e == DHT22_OK) {
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ESP_LOGI(TAG, "No errors reading DHT22 value");
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} else if (e == DHT22_CHECKSUM_ERROR) {
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ESP_LOGE(TAG, "Error calculating checksum");
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} else if (e == DHT22_TIMING_ERROR) {
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ESP_LOGE(TAG, "Timing error while obtaining data");
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}
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}
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dht22_error dht22_read() {
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uint8_t data[5] = {0};
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uint32_t tick_total = 0;
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/*
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* From datasheet:
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* - Host pulls low "beyond at least 1ms"
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* - Host pulls up 20us to 40us
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*/
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gpio_set_direction(CONFIG_DHT22_DATA_GPIO, GPIO_MODE_OUTPUT);
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gpio_set_level(CONFIG_DHT22_DATA_GPIO, 0);
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ets_delay_us(5000);
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gpio_set_level(CONFIG_DHT22_DATA_GPIO, 1);
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ets_delay_us(25);
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/*
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* From datasheet:
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* - DHT pulls low 80us
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* - DHT pulls high 80us
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*/
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gpio_set_direction(CONFIG_DHT22_DATA_GPIO, GPIO_MODE_INPUT);
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// Maybe wait here until it goes high?
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while (gpio_get_level(CONFIG_DHT22_DATA_GPIO) == 1) {
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// wait for a while - should only be 20 uS
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}
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uint64_t start_time = esp_timer_get_time();
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while (gpio_get_level(CONFIG_DHT22_DATA_GPIO) == 0) {
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tick_total += 1;
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if (tick_total == UINT32_MAX - 1) {
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return DHT22_TIMING_ERROR;
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}
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}
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uint64_t next_time = esp_timer_get_time();
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uint32_t elapsed_time = next_time - start_time;
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if (elapsed_time < 75 || elapsed_time > 85) {
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return DHT22_TIMING_ERROR;
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}
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tick_total = 0;
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start_time = esp_timer_get_time();
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while (gpio_get_level(CONFIG_DHT22_DATA_GPIO) == 0) {
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tick_total += 1;
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if (tick_total == UINT32_MAX - 1) {
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return DHT22_TIMING_ERROR;
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}
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}
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next_time = esp_timer_get_time();
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elapsed_time = next_time - start_time;
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portENABLE_INTERRUPTS();
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ESP_LOGW(TAG, "etime: %lu", elapsed_time);
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if (elapsed_time < 70 || elapsed_time > 90) {
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return DHT22_TIMING_ERROR;
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}
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// TODO test that data[x] << 8 will be promoted to 16bits otherwise I'm
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// shifting them to just zeros
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_dht22_relative_humidity = data[0] << 8 | data[1];
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_dht22_temperature = (data[2] & 0x7f) << 8 | data[3];
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if (data[2] & 0x80) {
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_dht22_temperature = -1 * _dht22_temperature;
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}
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uint8_t checksum_val = (data[0] + data[1] + data[2] + data[3]) & 0xff;
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if (checksum_val != data[4]) {
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_dht22_relative_humidity = UINT16_MAX;
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_dht22_temperature = INT16_MIN;
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return DHT22_CHECKSUM_ERROR;
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}
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return DHT22_OK;
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}
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deci_percent dht22_relative_humidity() { return _dht22_relative_humidity; }
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deci_degrees_c dht22_temperature() { return _dht22_temperature; }
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