dht22: unify DHT11 and DHT22 libraries
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/** library to query measurements from Aosong DHT11 temperature and relative humidity sensor
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* @file
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @copyright SPDX-License-Identifier: GPL-3.0-or-later
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* @date 2017-2020
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* @note peripherals used: timer channel @ref sensor_dht11_timer
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*/
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/* standard libraries */
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#include <stdint.h> // standard integer types
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/* STM32 (including CM3) libraries */
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#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
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#include <libopencm3/cm3/nvic.h> // interrupt handler
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#include <libopencm3/stm32/rcc.h> // real-time control clock library
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#include <libopencm3/stm32/gpio.h> // general purpose input output library
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#include <libopencm3/stm32/timer.h> // timer utilities
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/* own libraries */
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#include "sensor_dht11.h" // PZEM electricity meter header and definitions
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#include "global.h" // common methods
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/** @defgroup sensor_dht11_timer timer peripheral used to measure signal timing for bit decoding
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* @{
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*/
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#define SENSOR_DHT11_TIMER 3 /**< timer peripheral */
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#define SENSOR_DHT11_CHANNEL 1 /**< channel used as input capture */
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#define SENSOR_DHT11_JITTER 0.1 /**< signal timing jitter tolerated in timing */
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/** @} */
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volatile bool sensor_dht11_measurement_received = false;
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/** communication states */
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volatile enum sensor_dht11_state_t {
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SENSOR_DHT11_OFF, // no request has started
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SENSOR_DHT11_HOST_START, // host starts request (and waits >18ms)
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SENSOR_DHT11_HOST_STARTED, // host started request and waits for slave answer
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SENSOR_DHT11_SLAVE_START, // slave responds to request and puts signal low for 80 us and high for 80 us
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SENSOR_DHT11_SLAVE_BIT, // slave is sending bit by putting signal low for 50 us and high (26-28 us = 0, 70 us = 1)
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SENSOR_DHT11_MAX
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} sensor_dht11_state = SENSOR_DHT11_OFF; /**< current communication state */
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/** the bit number being sent (MSb first), up to 40 */
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volatile uint8_t sensor_dht11_bit = 0;
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/** the 40 bits (5 bytes) being sent by the device */
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volatile uint8_t sensor_dht11_bits[5] = {0};
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/** reset all states */
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static void sensor_dht11_reset(void)
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{
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// reset states
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sensor_dht11_state = SENSOR_DHT11_OFF;
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sensor_dht11_bit = 0;
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sensor_dht11_measurement_received = false;
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gpio_set(TIM_CH_PORT(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL), TIM_CH_PIN(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL)); // idle is high (using pull-up resistor), pull-up before setting as output else the signal will be low for short
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gpio_set_mode(TIM_CH_PORT(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, TIM_CH_PIN(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL)); // setup GPIO pin as output (host starts communication before slave replies)
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timer_ic_disable(TIM(SENSOR_DHT11_TIMER), TIM_IC(SENSOR_DHT11_CHANNEL)); // enable capture interrupt only when receiving data
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timer_disable_counter(TIM(SENSOR_DHT11_TIMER)); // disable timer
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}
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void sensor_dht11_setup(void)
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{
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// setup timer to measure signal timing for bit decoding (use timer channel as input capture)
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rcc_periph_clock_enable(RCC_TIM_CH(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL)); // enable clock for GPIO peripheral
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rcc_periph_clock_enable(RCC_TIM(SENSOR_DHT11_TIMER)); // enable clock for timer peripheral
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rcc_periph_reset_pulse(RST_TIM(SENSOR_DHT11_TIMER)); // reset timer state
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timer_set_mode(TIM(SENSOR_DHT11_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock,edge alignment (simple count), and count up
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timer_set_prescaler(TIM(SENSOR_DHT11_TIMER), 20 - 1); // set the prescaler so this 16 bits timer allows to wait for 18 ms for the start signal ( 1/(72E6/20/(2**16))=18.20ms )
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timer_ic_set_input(TIM(SENSOR_DHT11_TIMER), TIM_IC(SENSOR_DHT11_CHANNEL), TIM_IC_IN_TI(SENSOR_DHT11_CHANNEL)); // configure ICx to use TIn
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timer_ic_set_filter(TIM(SENSOR_DHT11_TIMER), TIM_IC(SENSOR_DHT11_CHANNEL), TIM_IC_OFF); // use no filter input (precise timing needed)
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timer_ic_set_polarity(TIM(SENSOR_DHT11_TIMER), TIM_IC(SENSOR_DHT11_CHANNEL), TIM_IC_FALLING); // capture on rising edge
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timer_ic_set_prescaler(TIM(SENSOR_DHT11_TIMER), TIM_IC(SENSOR_DHT11_CHANNEL), TIM_IC_PSC_OFF); // don't use any prescaler since we want to capture every pulse
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timer_clear_flag(TIM(SENSOR_DHT11_TIMER), TIM_SR_UIF); // clear flag
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timer_update_on_overflow(TIM(SENSOR_DHT11_TIMER)); // only use counter overflow as UEV source (use overflow as start time or timeout)
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timer_enable_irq(TIM(SENSOR_DHT11_TIMER), TIM_DIER_UIE); // enable update interrupt for timer
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timer_clear_flag(TIM(SENSOR_DHT11_TIMER), TIM_SR_CCIF(SENSOR_DHT11_CHANNEL)); // clear input compare flag
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timer_enable_irq(TIM(SENSOR_DHT11_TIMER), TIM_DIER_CCIE(SENSOR_DHT11_CHANNEL)); // enable capture interrupt
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nvic_enable_irq(NVIC_TIM_IRQ(SENSOR_DHT11_TIMER)); // catch interrupt in service routine
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sensor_dht11_reset(); // reset state
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}
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bool sensor_dht11_measurement_request(void)
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{
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if (sensor_dht11_state != SENSOR_DHT11_OFF) { // not the right state to start (wait up until timeout to reset state)
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return false;
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}
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if (gpio_get(TIM_CH_PORT(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL), TIM_CH_PIN(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL)) == 0) { // signal should be high per default
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return false;
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}
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if (TIM_CR1(TIM(SENSOR_DHT11_TIMER)) & (TIM_CR1_CEN)) { // timer should be off
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return false;
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}
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sensor_dht11_reset(); // reset states
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// send start signal (pull low for > 18 ms)
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gpio_clear(TIM_CH_PORT(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL), TIM_CH_PIN(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL)); // set signal to low
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timer_set_counter(TIM(SENSOR_DHT11_TIMER), 0); // reset timer counter
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timer_enable_counter(TIM(SENSOR_DHT11_TIMER)); // enable timer to wait for 18 ms until overflow
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sensor_dht11_state = SENSOR_DHT11_HOST_START; // remember we started sending signal
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return true;
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}
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struct sensor_dht11_measurement_t sensor_dht11_measurement_decode(void)
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{
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struct sensor_dht11_measurement_t measurement = { 0xff, 0xff }; // measurement to return
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if (sensor_dht11_bit < 40) { // not enough bits received
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return measurement;
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}
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if ((uint8_t)(sensor_dht11_bits[0] + sensor_dht11_bits[1] + sensor_dht11_bits[2] + sensor_dht11_bits[3]) != sensor_dht11_bits[4]) { // error in checksum (not really parity bit, as mentioned in the datasheet)
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return measurement;
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}
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// calculate measured values (byte 1 and 3 should be the factional value but they are always 0)
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measurement.humidity = sensor_dht11_bits[0];
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measurement.temperature = sensor_dht11_bits[2];
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return measurement;
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}
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/** interrupt service routine called for timer */
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void TIM_ISR(SENSOR_DHT11_TIMER)(void)
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{
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if (timer_get_flag(TIM(SENSOR_DHT11_TIMER), TIM_SR_UIF)) { // overflow update event happened
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timer_clear_flag(TIM(SENSOR_DHT11_TIMER), TIM_SR_UIF); // clear flag
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if (sensor_dht11_state == SENSOR_DHT11_HOST_START) { // start signal sent
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gpio_set_mode(TIM_CH_PORT(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, TIM_CH_PIN(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL)); // switch pin to input (the external pull up with also set the signal high)
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sensor_dht11_state = SENSOR_DHT11_HOST_STARTED; // switch to next state
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timer_ic_enable(TIM(SENSOR_DHT11_TIMER), TIM_IC(SENSOR_DHT11_CHANNEL)); // enable capture interrupt only when receiving data
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} else { // timeout occurred
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sensor_dht11_reset(); // reset states
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}
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} else if (timer_get_flag(TIM(SENSOR_DHT11_TIMER), TIM_SR_CCIF(SENSOR_DHT11_CHANNEL))) { // edge detected on input capture
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uint16_t time = TIM_CCR(SENSOR_DHT11_TIMER,SENSOR_DHT11_CHANNEL); // save captured bit timing (this clear also the flag)
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timer_set_counter(TIM(SENSOR_DHT11_TIMER), 0); // reset timer counter
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time = (time * 1E6) / (rcc_ahb_frequency / (TIM_PSC(TIM(SENSOR_DHT11_TIMER)) + 1)); // calculate time in us
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switch (sensor_dht11_state) {
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case (SENSOR_DHT11_HOST_STARTED): // the host query data and the slave is responding
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sensor_dht11_state = SENSOR_DHT11_SLAVE_START; // set new state
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break;
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case (SENSOR_DHT11_SLAVE_START): // the slave sent the start signal
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if (time >= ((80 + 80) * (1 - SENSOR_DHT11_JITTER)) && time <= ((80 + 80)*(1 + SENSOR_DHT11_JITTER))) { // response time should be 80 us low and 80 us high
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sensor_dht11_state = SENSOR_DHT11_SLAVE_BIT; // set new state
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} else {
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goto error;
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}
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break;
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case (SENSOR_DHT11_SLAVE_BIT): // the slave sent a bit
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if (sensor_dht11_bit >= 40) { // no bits should be received after 40 bits
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goto error;
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}
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if (time >= ((50 + 26) * (1 - SENSOR_DHT11_JITTER)) && time <= ((50 + 28) * (1 + SENSOR_DHT11_JITTER))) { // bit 0 time should be 50 us low and 26-28 us high
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sensor_dht11_bits[sensor_dht11_bit / 8] &= ~(1 << (7 - (sensor_dht11_bit % 8))); // clear bit
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} else if (time >= ((50 + 70)*(1 - SENSOR_DHT11_JITTER)) && time <= ((50 + 70) * (1 + SENSOR_DHT11_JITTER))) { // bit 1 time should be 50 us low and 70 us high
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sensor_dht11_bits[sensor_dht11_bit / 8] |= (1 << (7 - (sensor_dht11_bit % 8))); // set bit
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} else {
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goto error;
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}
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sensor_dht11_bit++;
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if (sensor_dht11_bit >= 40) { // all bits received
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sensor_dht11_reset(); // reset states
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sensor_dht11_bit = 40; // signal decoder all bits have been received
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sensor_dht11_measurement_received = true; // signal user all bits have been received
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}
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break;
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default: // unexpected state
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error:
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sensor_dht11_reset(); // reset states
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}
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} else { // no other interrupt should occur
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while (true); // unhandled exception: wait for the watchdog to bite
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}
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}
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@ -1,28 +0,0 @@
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/** library to query measurements from Aosong DHT11 temperature and relative humidity sensor
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* @file
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @copyright SPDX-License-Identifier: GPL-3.0-or-later
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* @date 2017-2020
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* @note peripherals used: timer channel @ref sensor_dht11_timer (add external pull-up resistor)
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*/
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#pragma once
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/** a measurement response has been received */
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extern volatile bool sensor_dht11_measurement_received;
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/** measurement returned by sensor */
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struct sensor_dht11_measurement_t {
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uint8_t humidity; /**< relative humidity in %RH (20-95) */
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uint8_t temperature; /**< temperature in °C (0-50) */
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};
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/** setup peripherals to communicate with sensor */
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void sensor_dht11_setup(void);
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/** request measurement from sensor
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* @return request started successfully
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*/
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bool sensor_dht11_measurement_request(void);
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/** decode received measurement
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* @return decoded measurement (0xff,0xff if invalid)
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*/
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struct sensor_dht11_measurement_t sensor_dht11_measurement_decode(void);
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@ -0,0 +1,206 @@
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/** library to query measurements from Aosong and DHT22/AM2302 temperature and relative humidity sensor
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* @file
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @copyright SPDX-License-Identifier: GPL-3.0-or-later
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* @date 2017-2020
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* @note peripherals used: timer channel @ref sensor_dht1122_timer
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*/
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/* standard libraries */
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#include <stdint.h> // standard integer types
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/* STM32 (including CM3) libraries */
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#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
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#include <libopencm3/cm3/nvic.h> // interrupt handler
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#include <libopencm3/stm32/rcc.h> // real-time control clock library
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#include <libopencm3/stm32/gpio.h> // general purpose input output library
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#include <libopencm3/stm32/timer.h> // timer utilities
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/* own libraries */
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#include "sensor_dht1122.h" // PZEM electricity meter header and definitions
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#include "global.h" // common methods
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/** @defgroup sensor_dht1122_timer timer peripheral used to measure signal timing for bit decoding
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* @{
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*/
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#define SENSOR_DHT1122_PIN PB4 /**< MCU pin connected to DHT1122 I/O pin, pulled up externally */
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#define SENSOR_DHT1122_TIMER 3 /**< timer peripheral for DHT1122 pin */
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#define SENSOR_DHT1122_CHANNEL 1 /**< channel used as input capture */
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#define SENSOR_DHT1122_AF GPIO_AF2 /**< pin alternate function to use as timer */
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#define SENSOR_DHT1122_JITTER 0.2 /**< signal timing jitter tolerated in timing */
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/** @} */
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volatile bool sensor_dht1122_measurement_received = false;
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/** remember if the sensor is a DHT11 or DHT22 */
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static bool sensor_dht1122_dht22 = false;
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/** communication states */
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volatile enum sensor_dht1122_state_t {
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SENSOR_DHT1122_OFF, // no request has started
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SENSOR_DHT1122_HOST_START, // host starts request (and waits >18ms)
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SENSOR_DHT1122_HOST_STARTED, // host started request and waits for slave answer
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SENSOR_DHT1122_SLAVE_START, // slave responds to request and puts signal low for 80 us and high for 80 us
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SENSOR_DHT1122_SLAVE_BIT, // slave is sending bit by putting signal low for 50 us and high (26-28 us = 0, 70 us = 1)
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SENSOR_DHT1122_MAX
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} sensor_dht1122_state = SENSOR_DHT1122_OFF; /**< current communication state */
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/** the bit number being sent (MSb first), up to 40 */
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volatile uint8_t sensor_dht1122_bit = 0;
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/** the 40 bits (5 bytes) being sent by the device */
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volatile uint8_t sensor_dht1122_bits[5] = {0};
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/** reset all states */
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static void sensor_dht1122_reset(void)
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{
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// reset states
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sensor_dht1122_state = SENSOR_DHT1122_OFF;
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sensor_dht1122_bit = 0;
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sensor_dht1122_measurement_received = false;
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gpio_set(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_PIN(SENSOR_DHT1122_PIN)); // idle is high (using pull-up resistor), pull-up before setting as output else the signal will be low for short
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gpio_mode_setup(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN(SENSOR_DHT1122_PIN)); // setup GPIO pin as output (host starts communication before slave replies)
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timer_ic_disable(TIM(SENSOR_DHT1122_TIMER), TIM_IC(SENSOR_DHT1122_CHANNEL)); // disable capture interrupt only when receiving data
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timer_disable_counter(TIM(SENSOR_DHT1122_TIMER)); // disable timer
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}
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void sensor_dht1122_setup(bool dht22)
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{
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sensor_dht1122_dht22 = dht22; // remember sensor type
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// configure pin to use as timer input
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rcc_periph_clock_enable(GPIO_RCC(SENSOR_DHT1122_PIN)); // enable clock for I²C I/O peripheral
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gpio_set(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_PIN(SENSOR_DHT1122_PIN)); // already put signal high
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gpio_mode_setup(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN(SENSOR_DHT1122_PIN)); // set pin to alternate function
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gpio_set_output_options(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_OTYPE_OD, GPIO_OSPEED_25MHZ, GPIO_PIN(SENSOR_DHT1122_PIN)); // set pin output as open-drain
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gpio_set_af(GPIO_PORT(SENSOR_DHT1122_PIN), SENSOR_DHT1122_AF, GPIO_PIN(SENSOR_DHT1122_PIN)); // set alternate function to pin
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// setup timer to measure signal timing for bit decoding (use timer channel as input capture)
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rcc_periph_clock_enable(RCC_TIM(SENSOR_DHT1122_TIMER)); // enable clock for timer peripheral
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rcc_periph_reset_pulse(RST_TIM(SENSOR_DHT1122_TIMER)); // reset timer state
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timer_set_mode(TIM(SENSOR_DHT1122_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock,edge alignment (simple count), and count up
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timer_enable_break_main_output(TIM(SENSOR_DHT1122_TIMER)); // required to enable some timer, even when no dead time is used
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// one difference between DHT11 and DHT22 is the request pulse duration
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if (!sensor_dht1122_dht22) { // for DHT11
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timer_set_prescaler(TIM(SENSOR_DHT1122_TIMER), 24 - 1); // set the prescaler so this 16 bits timer allows to wait for 18 ms for the start signal ( 1/(84E6/24/(2**16)) = 18.7 ms )
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} else { // for DHT22
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timer_set_prescaler(TIM(SENSOR_DHT1122_TIMER), 2 - 1); // set the prescaler so this 16 bits timer allows to wait for 18 ms for the start signal ( 1/(84E6/2/(2**16)) = 1.56 ms )
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}
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timer_ic_set_input(TIM(SENSOR_DHT1122_TIMER), TIM_IC(SENSOR_DHT1122_CHANNEL), TIM_IC_IN_TI(SENSOR_DHT1122_CHANNEL)); // configure ICx to use TIn
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timer_ic_set_filter(TIM(SENSOR_DHT1122_TIMER), TIM_IC(SENSOR_DHT1122_CHANNEL), TIM_IC_OFF); // use no filter input (precise timing needed)
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timer_ic_set_polarity(TIM(SENSOR_DHT1122_TIMER), TIM_IC(SENSOR_DHT1122_CHANNEL), TIM_IC_FALLING); // capture on falling edge (start of bit)
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timer_ic_set_prescaler(TIM(SENSOR_DHT1122_TIMER), TIM_IC(SENSOR_DHT1122_CHANNEL), TIM_IC_PSC_OFF); // don't use any prescaler since we want to capture every pulse
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timer_clear_flag(TIM(SENSOR_DHT1122_TIMER), TIM_SR_UIF); // clear flag
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timer_update_on_overflow(TIM(SENSOR_DHT1122_TIMER)); // only use counter overflow as UEV source (use overflow as start time or timeout)
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timer_enable_irq(TIM(SENSOR_DHT1122_TIMER), TIM_DIER_UIE); // enable update interrupt for timer
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|
||||
timer_clear_flag(TIM(SENSOR_DHT1122_TIMER), TIM_SR_CCIF(SENSOR_DHT1122_CHANNEL)); // clear input compare flag
|
||||
timer_enable_irq(TIM(SENSOR_DHT1122_TIMER), TIM_DIER_CCIE(SENSOR_DHT1122_CHANNEL)); // enable capture interrupt
|
||||
|
||||
nvic_enable_irq(NVIC_TIM_IRQ(SENSOR_DHT1122_TIMER)); // catch interrupt in service routine
|
||||
|
||||
sensor_dht1122_reset(); // reset state
|
||||
}
|
||||
|
||||
bool sensor_dht1122_measurement_request(void)
|
||||
{
|
||||
if (sensor_dht1122_state != SENSOR_DHT1122_OFF) { // not the right state to start (wait up until timeout to reset state)
|
||||
return false;
|
||||
}
|
||||
if (gpio_get(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_PIN(SENSOR_DHT1122_PIN)) == 0) { // signal should be high per default
|
||||
return false;
|
||||
}
|
||||
if (TIM_CR1(TIM(SENSOR_DHT1122_TIMER)) & (TIM_CR1_CEN)) { // timer should be off
|
||||
return false;
|
||||
}
|
||||
sensor_dht1122_reset(); // reset states
|
||||
|
||||
// send start signal (pull low for > 18 ms)
|
||||
gpio_clear(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_PIN(SENSOR_DHT1122_PIN)); // set signal to low
|
||||
timer_set_counter(TIM(SENSOR_DHT1122_TIMER), 0); // reset timer counter
|
||||
timer_enable_counter(TIM(SENSOR_DHT1122_TIMER)); // enable timer to wait for 18 ms until overflow
|
||||
sensor_dht1122_state = SENSOR_DHT1122_HOST_START; // remember we started sending signal
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
struct sensor_dht1122_measurement_t sensor_dht1122_measurement_decode(void)
|
||||
{
|
||||
struct sensor_dht1122_measurement_t measurement = { 0xff, 0xff }; // measurement to return
|
||||
if (sensor_dht1122_bit < 40) { // not enough bits received
|
||||
return measurement;
|
||||
}
|
||||
if ((uint8_t)(sensor_dht1122_bits[0] + sensor_dht1122_bits[1] + sensor_dht1122_bits[2] + sensor_dht1122_bits[3]) != sensor_dht1122_bits[4]) { // error in checksum (not really parity bit, as mentioned in the datasheet)
|
||||
return measurement;
|
||||
}
|
||||
if (0 == sensor_dht1122_bits[0] && 0 == sensor_dht1122_bits[1] && 0 == sensor_dht1122_bits[2] && 0 == sensor_dht1122_bits[3] && 0 == sensor_dht1122_bits[4]) { // this is measurement is very unlikely, there must be an error
|
||||
return measurement;
|
||||
}
|
||||
// the other difference between DHT11 and DHT22 is the encoding of the values
|
||||
if (!sensor_dht1122_dht22) { // for DHT11
|
||||
// calculate measured values (byte 1 and 3 should be the factional value but they are always 0)
|
||||
measurement.humidity = sensor_dht1122_bits[0];
|
||||
measurement.temperature = sensor_dht1122_bits[2];
|
||||
} else { // for DHT22
|
||||
measurement.humidity = (int16_t)((sensor_dht1122_bits[0] << 8) + sensor_dht1122_bits[1]) / 10.0;
|
||||
measurement.temperature = (int16_t)((sensor_dht1122_bits[2] << 8) + sensor_dht1122_bits[3]) / 10.0;
|
||||
}
|
||||
|
||||
return measurement;
|
||||
}
|
||||
|
||||
/** interrupt service routine called for timer */
|
||||
void TIM_ISR(SENSOR_DHT1122_TIMER)(void)
|
||||
{
|
||||
if (timer_get_flag(TIM(SENSOR_DHT1122_TIMER), TIM_SR_UIF)) { // overflow update event happened
|
||||
timer_clear_flag(TIM(SENSOR_DHT1122_TIMER), TIM_SR_UIF); // clear flag
|
||||
if (sensor_dht1122_state == SENSOR_DHT1122_HOST_START) { // start signal sent
|
||||
gpio_set(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_PIN(SENSOR_DHT1122_PIN)); // let pin go so we can use it as input
|
||||
gpio_mode_setup(GPIO_PORT(SENSOR_DHT1122_PIN), GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN(SENSOR_DHT1122_PIN)); // set pin to alternate function so the timer can read the pin
|
||||
sensor_dht1122_state = SENSOR_DHT1122_HOST_STARTED; // switch to next state
|
||||
timer_ic_enable(TIM(SENSOR_DHT1122_TIMER), TIM_IC(SENSOR_DHT1122_CHANNEL)); // enable capture interrupt only when receiving data
|
||||
} else { // timeout occurred
|
||||
sensor_dht1122_reset(); // reset states
|
||||
}
|
||||
} else if (timer_get_flag(TIM(SENSOR_DHT1122_TIMER), TIM_SR_CCIF(SENSOR_DHT1122_CHANNEL))) { // edge detected on input capture
|
||||
uint16_t time = TIM_CCR(SENSOR_DHT1122_TIMER, SENSOR_DHT1122_CHANNEL); // save captured bit timing (this clear also the flag)
|
||||
timer_set_counter(TIM(SENSOR_DHT1122_TIMER), 0); // reset timer counter
|
||||
time = (time * 1E6) / (rcc_ahb_frequency / (TIM_PSC(TIM(SENSOR_DHT1122_TIMER)) + 1)); // calculate time in us
|
||||
switch (sensor_dht1122_state) {
|
||||
case SENSOR_DHT1122_HOST_STARTED: // the host query data and the slave is responding
|
||||
sensor_dht1122_state = SENSOR_DHT1122_SLAVE_START; // set new state
|
||||
break;
|
||||
case SENSOR_DHT1122_SLAVE_START: // the slave sent the start signal
|
||||
if (time >= ((80 + 80) * (1 - SENSOR_DHT1122_JITTER)) && time <= ((80 + 80) * (1 + SENSOR_DHT1122_JITTER))) { // response time should be 80 us low and 80 us high
|
||||
sensor_dht1122_state = SENSOR_DHT1122_SLAVE_BIT; // set new state
|
||||
} else {
|
||||
goto error;
|
||||
}
|
||||
break;
|
||||
case SENSOR_DHT1122_SLAVE_BIT: // the slave sent a bit
|
||||
if (sensor_dht1122_bit >= 40) { // no bits should be received after 40 bits
|
||||
goto error;
|
||||
}
|
||||
if (time >= ((50 + 26) * (1 - SENSOR_DHT1122_JITTER)) && time <= ((50 + 28) * (1 + SENSOR_DHT1122_JITTER))) { // bit 0 time should be 50 us low and 26-28 us high
|
||||
sensor_dht1122_bits[sensor_dht1122_bit / 8] &= ~(1 << (7 - (sensor_dht1122_bit % 8))); // clear bit
|
||||
} else if (time >= ((50 + 70)*(1 - SENSOR_DHT1122_JITTER)) && time <= ((50 + 70) * (1 + SENSOR_DHT1122_JITTER))) { // bit 1 time should be 50 us low and 70 us high
|
||||
sensor_dht1122_bits[sensor_dht1122_bit / 8] |= (1 << (7 - (sensor_dht1122_bit % 8))); // set bit
|
||||
} else {
|
||||
goto error;
|
||||
}
|
||||
sensor_dht1122_bit++;
|
||||
if (sensor_dht1122_bit >= 40) { // all bits received
|
||||
sensor_dht1122_reset(); // reset states
|
||||
sensor_dht1122_bit = 40; // signal decoder all bits have been received
|
||||
sensor_dht1122_measurement_received = true; // signal user all bits have been received
|
||||
}
|
||||
break;
|
||||
default: // unexpected state
|
||||
error:
|
||||
sensor_dht1122_reset(); // reset states
|
||||
}
|
||||
} else { // no other interrupt should occur
|
||||
while (true); // unhandled exception: wait for the watchdog to bite
|
||||
}
|
||||
}
|
|
@ -0,0 +1,30 @@
|
|||
/** library to query measurements from Aosong DHT11 and DHT22/AM2302 temperature and relative humidity sensor
|
||||
* @file
|
||||
* @author King Kévin <kingkevin@cuvoodoo.info>
|
||||
* @copyright SPDX-License-Identifier: GPL-3.0-or-later
|
||||
* @date 2017-2021
|
||||
* @note peripherals used: timer channel @ref sensor_dht1122_timer (add external pull-up resistor)
|
||||
*/
|
||||
#pragma once
|
||||
|
||||
/** a measurement response has been received */
|
||||
extern volatile bool sensor_dht1122_measurement_received;
|
||||
|
||||
/** measurement returned by sensor */
|
||||
struct sensor_dht1122_measurement_t {
|
||||
float humidity; /**< relative humidity in %RH (20-95) */
|
||||
float temperature; /**< temperature in °C (0-50) */
|
||||
};
|
||||
|
||||
/** setup peripherals to communicate with sensor
|
||||
* @param[in] dht22 false for DHT11, true for DHT22/AM2302
|
||||
*/
|
||||
void sensor_dht1122_setup(bool dht22);
|
||||
/** request measurement from sensor
|
||||
* @return request started successfully
|
||||
*/
|
||||
bool sensor_dht1122_measurement_request(void);
|
||||
/** decode received measurement
|
||||
* @return decoded measurement (0xff,0xff if invalid)
|
||||
*/
|
||||
struct sensor_dht1122_measurement_t sensor_dht1122_measurement_decode(void);
|
|
@ -1,181 +0,0 @@
|
|||
/** library to query measurements from Aosong DHT22 temperature and relative humidity sensor
|
||||
* @file
|
||||
* @author King Kévin <kingkevin@cuvoodoo.info>
|
||||
* @copyright SPDX-License-Identifier: GPL-3.0-or-later
|
||||
* @date 2017-2020
|
||||
* @note peripherals used: GPIO and timer @ref sensor_dht22_timer
|
||||
* @note the DHT22 protocol is very similar but nit completely compatible with the DHT22 protocol: only 1 ms initial host pull low is required (vs. 18 ms), the data is encoded as int16_t (vs. uint8_t), and the signal has more jitter
|
||||
*/
|
||||
|
||||
/* standard libraries */
|
||||
#include <stdint.h> // standard integer types
|
||||
#include <math.h> // maths utilities
|
||||
|
||||
/* STM32 (including CM3) libraries */
|
||||
#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
|
||||
#include <libopencm3/cm3/nvic.h> // interrupt handler
|
||||
#include <libopencm3/stm32/rcc.h> // real-time control clock library
|
||||
#include <libopencm3/stm32/gpio.h> // general purpose input output library
|
||||
#include <libopencm3/stm32/timer.h> // timer utilities
|
||||
|
||||
/* own libraries */
|
||||
#include "sensor_dht22.h" // PZEM electricity meter header and definitions
|
||||
#include "global.h" // common methods
|
||||
|
||||
/** @defgroup sensor_dht22_timer timer peripheral used to measure signal timing for bit decoding
|
||||
* @{
|
||||
*/
|
||||
#define SENSOR_DHT22_TIMER 4 /**< timer peripheral */
|
||||
#define SENSOR_DHT22_CHANNEL 3 /**< channel used as input capture */
|
||||
#define SENSOR_DHT22_JITTER 0.2 /**< signal timing jitter tolerated in timing */
|
||||
/** @} */
|
||||
|
||||
volatile bool sensor_dht22_measurement_received = false;
|
||||
|
||||
/** communication states */
|
||||
volatile enum sensor_dht22_state_t {
|
||||
SENSOR_DHT22_OFF, // no request has started
|
||||
SENSOR_DHT22_HOST_START, // host starts request (and waits >18ms)
|
||||
SENSOR_DHT22_HOST_STARTED, // host started request and waits for slave answer
|
||||
SENSOR_DHT22_SLAVE_START, // slave responds to request and puts signal low for 80 us and high for 80 us
|
||||
SENSOR_DHT22_SLAVE_BIT, // slave is sending bit by putting signal low for 50 us and high (26-28 us = 0, 70 us = 1)
|
||||
SENSOR_DHT22_MAX
|
||||
} sensor_dht22_state = SENSOR_DHT22_OFF; /**< current communication state */
|
||||
|
||||
/** the bit number being sent (MSb first), up to 40 */
|
||||
volatile uint8_t sensor_dht22_bit = 0;
|
||||
|
||||
/** the 40 bits (5 bytes) being sent by the device */
|
||||
volatile uint8_t sensor_dht22_bits[5] = {0};
|
||||
|
||||
/** reset all states */
|
||||
static void sensor_dht22_reset(void)
|
||||
{
|
||||
// reset states
|
||||
sensor_dht22_state = SENSOR_DHT22_OFF;
|
||||
sensor_dht22_bit = 0;
|
||||
sensor_dht22_measurement_received = false;
|
||||
|
||||
gpio_set(TIM_CH_PORT(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL), TIM_CH_PIN(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL)); // idle is high (using pull-up resistor), pull-up before setting as output else the signal will be low for short
|
||||
gpio_set_mode(TIM_CH_PORT(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, TIM_CH_PIN(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL)); // setup GPIO pin as output (host starts communication before slave replies)
|
||||
|
||||
timer_ic_disable(TIM(SENSOR_DHT22_TIMER), TIM_IC(SENSOR_DHT22_CHANNEL)); // enable capture interrupt only when receiving data
|
||||
timer_disable_counter(TIM(SENSOR_DHT22_TIMER)); // disable timer
|
||||
}
|
||||
|
||||
void sensor_dht22_setup(void)
|
||||
{
|
||||
// setup timer to measure signal timing for bit decoding (use timer channel as input capture)
|
||||
rcc_periph_clock_enable(RCC_TIM_CH(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL)); // enable clock for GPIO peripheral
|
||||
rcc_periph_clock_enable(RCC_TIM(SENSOR_DHT22_TIMER)); // enable clock for timer peripheral
|
||||
rcc_periph_reset_pulse(RST_TIM(SENSOR_DHT22_TIMER)); // reset timer state
|
||||
timer_set_mode(TIM(SENSOR_DHT22_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock,edge alignment (simple count), and count up
|
||||
timer_set_prescaler(TIM(SENSOR_DHT22_TIMER), 2 - 1); // set the prescaler so this 16 bits timer allows to wait for 18 ms for the start signal ( 1/(72E6/2/(2**16))=1.820ms )
|
||||
timer_ic_set_input(TIM(SENSOR_DHT22_TIMER), TIM_IC(SENSOR_DHT22_CHANNEL), TIM_IC_IN_TI(SENSOR_DHT22_CHANNEL)); // configure ICx to use TIn
|
||||
timer_ic_set_filter(TIM(SENSOR_DHT22_TIMER), TIM_IC(SENSOR_DHT22_CHANNEL), TIM_IC_OFF); // use no filter input (precise timing needed)
|
||||
timer_ic_set_polarity(TIM(SENSOR_DHT22_TIMER), TIM_IC(SENSOR_DHT22_CHANNEL), TIM_IC_FALLING); // capture on rising edge
|
||||
timer_ic_set_prescaler(TIM(SENSOR_DHT22_TIMER), TIM_IC(SENSOR_DHT22_CHANNEL), TIM_IC_PSC_OFF); // don't use any prescaler since we want to capture every pulse
|
||||
|
||||
timer_clear_flag(TIM(SENSOR_DHT22_TIMER), TIM_SR_UIF); // clear flag
|
||||
timer_update_on_overflow(TIM(SENSOR_DHT22_TIMER)); // only use counter overflow as UEV source (use overflow as start time or timeout)
|
||||
timer_enable_irq(TIM(SENSOR_DHT22_TIMER), TIM_DIER_UIE); // enable update interrupt for timer
|
||||
|
||||
timer_clear_flag(TIM(SENSOR_DHT22_TIMER), TIM_SR_CCIF(SENSOR_DHT22_CHANNEL)); // clear input compare flag
|
||||
timer_enable_irq(TIM(SENSOR_DHT22_TIMER), TIM_DIER_CCIE(SENSOR_DHT22_CHANNEL)); // enable capture interrupt
|
||||
|
||||
nvic_enable_irq(NVIC_TIM_IRQ(SENSOR_DHT22_TIMER)); // catch interrupt in service routine
|
||||
|
||||
sensor_dht22_reset(); // reset state
|
||||
}
|
||||
|
||||
bool sensor_dht22_measurement_request(void)
|
||||
{
|
||||
if (sensor_dht22_state != SENSOR_DHT22_OFF) { // not the right state to start (wait up until timeout to reset state)
|
||||
return false;
|
||||
}
|
||||
if (gpio_get(TIM_CH_PORT(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL), TIM_CH_PIN(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL)) == 0) { // signal should be high per default
|
||||
return false;
|
||||
}
|
||||
if (TIM_CR1(TIM(SENSOR_DHT22_TIMER)) & (TIM_CR1_CEN)) { // timer should be off
|
||||
return false;
|
||||
}
|
||||
sensor_dht22_reset(); // reset states
|
||||
|
||||
// send start signal (pull low for > 1 ms)
|
||||
gpio_clear(TIM_CH_PORT(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL), TIM_CH_PIN(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL)); // set signal to low
|
||||
timer_set_counter(TIM(SENSOR_DHT22_TIMER), 0); // reset timer counter
|
||||
timer_enable_counter(TIM(SENSOR_DHT22_TIMER)); // enable timer to wait for 1.8 ms until overflow
|
||||
sensor_dht22_state = SENSOR_DHT22_HOST_START; // remember we started sending signal
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
struct sensor_dht22_measurement_t sensor_dht22_measurement_decode(void)
|
||||
{
|
||||
struct sensor_dht22_measurement_t measurement = { NAN, NAN }; // measurement to return
|
||||
if (sensor_dht22_bit < 40) { // not enough bits received
|
||||
return measurement;
|
||||
}
|
||||
if ((uint8_t)(sensor_dht22_bits[0] + sensor_dht22_bits[1] + sensor_dht22_bits[2] + sensor_dht22_bits[3]) != sensor_dht22_bits[4]) { // error in checksum (not really parity bit, as mentioned in the datasheet)
|
||||
return measurement;
|
||||
}
|
||||
// calculate measured values (stored as uint16_t deci-value)
|
||||
measurement.humidity = (int16_t)((sensor_dht22_bits[0] << 8) + sensor_dht22_bits[1]) / 10.0;
|
||||
measurement.temperature = (int16_t)((sensor_dht22_bits[2] << 8) + sensor_dht22_bits[3]) / 10.0;
|
||||
|
||||
return measurement;
|
||||
}
|
||||
|
||||
/** interrupt service routine called for timer */
|
||||
void TIM_ISR(SENSOR_DHT22_TIMER)(void)
|
||||
{
|
||||
if (timer_get_flag(TIM(SENSOR_DHT22_TIMER), TIM_SR_UIF)) { // overflow update event happened
|
||||
timer_clear_flag(TIM(SENSOR_DHT22_TIMER), TIM_SR_UIF); // clear flag
|
||||
if (sensor_dht22_state==SENSOR_DHT22_HOST_START) { // start signal sent
|
||||
gpio_set_mode(TIM_CH_PORT(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, TIM_CH_PIN(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL)); // switch pin to input (the external pull up with also set the signal high)
|
||||
sensor_dht22_state = SENSOR_DHT22_HOST_STARTED; // switch to next state
|
||||
timer_ic_enable(TIM(SENSOR_DHT22_TIMER), TIM_IC(SENSOR_DHT22_CHANNEL)); // enable capture interrupt only when receiving data
|
||||
} else { // timeout occurred
|
||||
sensor_dht22_reset(); // reset states
|
||||
}
|
||||
} else if (timer_get_flag(TIM(SENSOR_DHT22_TIMER), TIM_SR_CCIF(SENSOR_DHT22_CHANNEL))) { // edge detected on input capture
|
||||
uint16_t time = TIM_CCR(SENSOR_DHT22_TIMER,SENSOR_DHT22_CHANNEL); // save captured bit timing (this clear also the flag)
|
||||
timer_set_counter(TIM(SENSOR_DHT22_TIMER), 0); // reset timer counter
|
||||
time = (time * 1E6) / (rcc_ahb_frequency / (TIM_PSC(TIM(SENSOR_DHT22_TIMER)) + 1)); // calculate time in us
|
||||
switch (sensor_dht22_state) {
|
||||
case (SENSOR_DHT22_HOST_STARTED): // the host query data and the slave is responding
|
||||
sensor_dht22_state = SENSOR_DHT22_SLAVE_START; // set new state
|
||||
break;
|
||||
case (SENSOR_DHT22_SLAVE_START): // the slave sent the start signal
|
||||
if (time >= ((80 + 80) * (1 - SENSOR_DHT22_JITTER)) && time <= ((80 + 80) * (1 + SENSOR_DHT22_JITTER))) { // response time should be 80 us low and 80 us high
|
||||
sensor_dht22_state = SENSOR_DHT22_SLAVE_BIT; // set new state
|
||||
} else {
|
||||
goto error;
|
||||
}
|
||||
break;
|
||||
case (SENSOR_DHT22_SLAVE_BIT): // the slave sent a bit
|
||||
if (sensor_dht22_bit >= 40) { // no bits should be received after 40 bits
|
||||
goto error;
|
||||
}
|
||||
if (time >= ((50 + 26) * (1 - SENSOR_DHT22_JITTER)) && time <= ((50 + 28) * (1 + SENSOR_DHT22_JITTER))) { // bit 0 time should be 50 us low and 26-28 us high
|
||||
sensor_dht22_bits[sensor_dht22_bit / 8] &= ~(1 << (7 - (sensor_dht22_bit % 8))); // clear bit
|
||||
} else if (time >= ((50 + 70) * (1 - SENSOR_DHT22_JITTER)) && time <= ((50 + 70) * (1 + SENSOR_DHT22_JITTER))) { // bit 1 time should be 50 us low and 70 us high
|
||||
sensor_dht22_bits[sensor_dht22_bit / 8] |= (1 << (7 - (sensor_dht22_bit % 8))); // set bit
|
||||
} else {
|
||||
goto error;
|
||||
}
|
||||
sensor_dht22_bit++;
|
||||
if (sensor_dht22_bit >= 40) { // all bits received
|
||||
sensor_dht22_reset(); // reset states
|
||||
sensor_dht22_bit = 40; // signal decoder all bits have been received
|
||||
sensor_dht22_measurement_received = true; // signal user all bits have been received
|
||||
}
|
||||
break;
|
||||
default: // unexpected state
|
||||
error:
|
||||
sensor_dht22_reset(); // reset states
|
||||
}
|
||||
} else { // no other interrupt should occur
|
||||
while (true); // unhandled exception: wait for the watchdog to bite
|
||||
}
|
||||
}
|
|
@ -1,28 +0,0 @@
|
|||
/** library to query measurements from Aosong DHT22 (aka. AM2302) temperature and relative humidity sensor
|
||||
* @file
|
||||
* @author King Kévin <kingkevin@cuvoodoo.info>
|
||||
* @copyright SPDX-License-Identifier: GPL-3.0-or-later
|
||||
* @date 2017-2020
|
||||
* @note peripherals used: timer channel @ref sensor_dht22_timer (add external pull-up resistor)
|
||||
*/
|
||||
#pragma once
|
||||
|
||||
/** a measurement response has been received */
|
||||
extern volatile bool sensor_dht22_measurement_received;
|
||||
|
||||
/** measurement returned by sensor */
|
||||
struct sensor_dht22_measurement_t {
|
||||
float humidity; /**< relative humidity in %RH (0-100) */
|
||||
float temperature; /**< temperature in °C (-40-80) */
|
||||
};
|
||||
|
||||
/** setup peripherals to communicate with sensor */
|
||||
void sensor_dht22_setup(void);
|
||||
/** request measurement from sensor
|
||||
* @return request started successfully
|
||||
*/
|
||||
bool sensor_dht22_measurement_request(void);
|
||||
/** decode received measurement
|
||||
* @return decoded measurement (0xff,0xff if invalid)
|
||||
*/
|
||||
struct sensor_dht22_measurement_t sensor_dht22_measurement_decode(void);
|
Loading…
Reference in New Issue