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Refactor pulse_meter to better handle higher frequencies (esphome#4231
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@TrentHouliston
TrentHouliston authored Aug 7, 2023
1 parent 40697fe commit 93b7ca7
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Showing 2 changed files with 103 additions and 148 deletions.
204 changes: 75 additions & 129 deletions esphome/components/pulse_meter/pulse_meter_sensor.cpp
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
#include "pulse_meter_sensor.h"
#include <utility>
#include "esphome/core/log.h"

namespace esphome {
Expand All @@ -9,66 +10,58 @@ static const char *const TAG = "pulse_meter";
void PulseMeterSensor::setup() {
this->pin_->setup();
this->isr_pin_ = pin_->to_isr();
this->pin_->attach_interrupt(PulseMeterSensor::gpio_intr, this, gpio::INTERRUPT_ANY_EDGE);

this->last_detected_edge_us_ = 0;
this->last_valid_edge_us_ = 0;
this->pulse_width_us_ = 0;
this->sensor_is_high_ = this->isr_pin_.digital_read();
this->has_valid_edge_ = false;
this->pending_state_change_ = NONE;

if (this->filter_mode_ == FILTER_EDGE) {
this->pin_->attach_interrupt(PulseMeterSensor::edge_intr, this, gpio::INTERRUPT_RISING_EDGE);
} else if (this->filter_mode_ == FILTER_PULSE) {
this->pin_->attach_interrupt(PulseMeterSensor::pulse_intr, this, gpio::INTERRUPT_ANY_EDGE);
}
}
// In PULSE mode we set a flag (pending_state_change_) for every interrupt
// that constitutes a state change. In the loop() method we check if a time
// interval greater than the internal_filter time has passed without any
// interrupts.

void PulseMeterSensor::loop() {
// Get a snapshot of the needed volatile sensor values, to make sure they are not
// modified by the ISR while we are in the loop() method. If they are changed
// after we the variable "now" has been set, overflow will occur in the
// subsequent arithmetic
const bool has_valid_edge = this->has_valid_edge_;
const uint32_t last_detected_edge_us = this->last_detected_edge_us_;
const uint32_t last_valid_edge_us = this->last_valid_edge_us_;
// Get the current time after the snapshot of saved times
const uint32_t now = micros();

this->handle_state_change_(now, last_detected_edge_us, last_valid_edge_us, has_valid_edge);

// If we've exceeded our timeout interval without receiving any pulses, assume 0 pulses/min until
// we get at least two valid pulses.
const uint32_t time_since_valid_edge_us = now - last_detected_edge_us;
if ((has_valid_edge) && (time_since_valid_edge_us > this->timeout_us_)) {
ESP_LOGD(TAG, "No pulse detected for %us, assuming 0 pulses/min", time_since_valid_edge_us / 1000000);

this->last_valid_edge_us_ = 0;
this->pulse_width_us_ = 0;
this->has_valid_edge_ = false;
this->last_detected_edge_us_ = 0;
}
// Reset the count in get before we pass it back to the ISR as set
this->get_->count_ = 0;

// Swap out set and get to get the latest state from the ISR
// The ISR could interrupt on any of these lines and the results would be consistent
auto *temp = this->set_;
this->set_ = this->get_;
this->get_ = temp;

// Check if we detected a pulse this loop
if (this->get_->count_ > 0) {
// Keep a running total of pulses if a total sensor is configured
if (this->total_sensor_ != nullptr) {
this->total_pulses_ += this->get_->count_;
const uint32_t total = this->total_pulses_;
this->total_sensor_->publish_state(total);
}

// We quantize our pulse widths to 1 ms to avoid unnecessary jitter
const uint32_t pulse_width_ms = this->pulse_width_us_ / 1000;
if (this->pulse_width_dedupe_.next(pulse_width_ms)) {
if (pulse_width_ms == 0) {
// Treat 0 pulse width as 0 pulses/min (normally because we've not detected any pulses for a while)
this->publish_state(0);
// We need to detect at least two edges to have a valid pulse width
if (!this->initialized_) {
this->initialized_ = true;
} else {
// Calculate pulses/min from the pulse width in ms
this->publish_state((60.0f * 1000.0f) / pulse_width_ms);
uint32_t delta_us = this->get_->last_detected_edge_us_ - this->last_processed_edge_us_;
float pulse_width_us = delta_us / float(this->get_->count_);
this->publish_state((60.0f * 1000000.0f) / pulse_width_us);
}
}

if (this->total_sensor_ != nullptr) {
const uint32_t total = this->total_pulses_;
if (this->total_dedupe_.next(total)) {
this->total_sensor_->publish_state(total);
this->last_processed_edge_us_ = this->get_->last_detected_edge_us_;
}
// No detected edges this loop
else {
const uint32_t now = micros();
const uint32_t time_since_valid_edge_us = now - this->last_processed_edge_us_;

if (this->initialized_ && time_since_valid_edge_us > this->timeout_us_) {
ESP_LOGD(TAG, "No pulse detected for %us, assuming 0 pulses/min", time_since_valid_edge_us / 1000000);
this->initialized_ = false;
this->publish_state(0.0f);
}
}
}

void PulseMeterSensor::set_total_pulses(uint32_t pulses) { this->total_pulses_ = pulses; }
float PulseMeterSensor::get_setup_priority() const { return setup_priority::DATA; }

void PulseMeterSensor::dump_config() {
LOG_SENSOR("", "Pulse Meter", this);
Expand All @@ -81,96 +74,49 @@ void PulseMeterSensor::dump_config() {
ESP_LOGCONFIG(TAG, " Assuming 0 pulses/min after not receiving a pulse for %us", this->timeout_us_ / 1000000);
}

void IRAM_ATTR PulseMeterSensor::gpio_intr(PulseMeterSensor *sensor) {
void IRAM_ATTR PulseMeterSensor::edge_intr(PulseMeterSensor *sensor) {
// This is an interrupt handler - we can't call any virtual method from this method
// Get the current time before we do anything else so the measurements are consistent
const uint32_t now = micros();
const bool pin_val = sensor->isr_pin_.digital_read();

if (sensor->filter_mode_ == FILTER_EDGE) {
// We only look at rising edges
if (!pin_val) {
return;
}
// Check to see if we should filter this edge out
if ((now - sensor->last_detected_edge_us_) >= sensor->filter_us_) {
// Don't measure the first valid pulse (we need at least two pulses to measure the width)
if (sensor->has_valid_edge_) {
sensor->pulse_width_us_ = (now - sensor->last_valid_edge_us_);
}
sensor->total_pulses_++;
sensor->last_valid_edge_us_ = now;
sensor->has_valid_edge_ = true;
}
sensor->last_detected_edge_us_ = now;
} else {
// Filter Mode is PULSE
const uint32_t delta_t_us = now - sensor->last_detected_edge_us_;
// We need to check if we have missed to handle a state change in the
// loop() function. This can happen when the filter_us value is less than
// the loop() interval, which is ~50-60ms
// The section below is essentially a modified repeat of the
// handle_state_change method. Ideally i would refactor and call the
// method here as well. However functions called in ISRs need to meet
// strict criteria and I don't think the methos would meet them.
if (sensor->pending_state_change_ != NONE && (delta_t_us > sensor->filter_us_)) {
// We have missed to handle a state change in the loop function.
sensor->sensor_is_high_ = sensor->pending_state_change_ == TO_HIGH;
if (sensor->sensor_is_high_) {
// We need to handle a pulse that would have been missed by the loop function
sensor->total_pulses_++;
if (sensor->has_valid_edge_) {
sensor->pulse_width_us_ = sensor->last_detected_edge_us_ - sensor->last_valid_edge_us_;
sensor->has_valid_edge_ = true;
sensor->last_valid_edge_us_ = sensor->last_detected_edge_us_;
}
}
} // End of checking for and handling of change in state

// Ignore false edges that may be caused by bouncing and exit the ISR ASAP
if (pin_val == sensor->sensor_is_high_) {
sensor->pending_state_change_ = NONE;
return;
}
sensor->pending_state_change_ = pin_val ? TO_HIGH : TO_LOW;
sensor->last_detected_edge_us_ = now;
if ((now - sensor->last_edge_candidate_us_) >= sensor->filter_us_) {
sensor->last_edge_candidate_us_ = now;
sensor->set_->last_detected_edge_us_ = now;
sensor->set_->count_++;
}
}

void PulseMeterSensor::handle_state_change_(uint32_t now, uint32_t last_detected_edge_us, uint32_t last_valid_edge_us,
bool has_valid_edge) {
if (this->pending_state_change_ == NONE) {
return;
}

const bool pin_val = this->isr_pin_.digital_read();
if (pin_val == this->sensor_is_high_) {
// Most likely caused by high frequency bouncing. Theoretically we should
// expect interrupts of alternating state. Here we are registering an
// interrupt with no change in state. Another interrupt will likely trigger
// just after this one and have an alternate state.
this->pending_state_change_ = NONE;
return;
}

if ((now - last_detected_edge_us) > this->filter_us_) {
this->sensor_is_high_ = pin_val;
ESP_LOGVV(TAG, "State is now %s", pin_val ? "high" : "low");

// Increment with valid rising edges only
if (pin_val) {
this->total_pulses_++;
ESP_LOGVV(TAG, "Incremented pulses to %u", this->total_pulses_);
void IRAM_ATTR PulseMeterSensor::pulse_intr(PulseMeterSensor *sensor) {
// This is an interrupt handler - we can't call any virtual method from this method
// Get the current time before we do anything else so the measurements are consistent
const uint32_t now = micros();
const bool pin_val = sensor->isr_pin_.digital_read();

if (has_valid_edge) {
this->pulse_width_us_ = last_detected_edge_us - last_valid_edge_us;
ESP_LOGVV(TAG, "Set pulse width to %u", this->pulse_width_us_);
// A pulse occurred faster than we can detect
if (sensor->last_pin_val_ == pin_val) {
// If we haven't reached the filter length yet we need to reset our last_intr_ to now
// otherwise we can consider this noise as the "pulse" was certainly less than filter_us_
if (now - sensor->last_intr_ < sensor->filter_us_) {
sensor->last_intr_ = now;
}
} else {
// Check if the last interrupt was long enough in the past
if (now - sensor->last_intr_ > sensor->filter_us_) {
// High pulse of filter length now falling (therefore last_intr_ was the rising edge)
if (!sensor->in_pulse_ && sensor->last_pin_val_) {
sensor->last_edge_candidate_us_ = sensor->last_intr_;
sensor->in_pulse_ = true;
}
// Low pulse of filter length now rising (therefore last_intr_ was the falling edge)
else if (sensor->in_pulse_ && !sensor->last_pin_val_) {
sensor->set_->last_detected_edge_us_ = sensor->last_edge_candidate_us_;
sensor->set_->count_++;
sensor->in_pulse_ = false;
}
this->has_valid_edge_ = true;
this->last_valid_edge_us_ = last_detected_edge_us;
ESP_LOGVV(TAG, "last_valid_edge_us_ is now %u", this->last_valid_edge_us_);
}
this->pending_state_change_ = NONE;

sensor->last_intr_ = now;
sensor->last_pin_val_ = pin_val;
}
}

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47 changes: 28 additions & 19 deletions esphome/components/pulse_meter/pulse_meter_sensor.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,41 +17,50 @@ class PulseMeterSensor : public sensor::Sensor, public Component {

void set_pin(InternalGPIOPin *pin) { this->pin_ = pin; }
void set_filter_us(uint32_t filter) { this->filter_us_ = filter; }
void set_filter_mode(InternalFilterMode mode) { this->filter_mode_ = mode; }
void set_timeout_us(uint32_t timeout) { this->timeout_us_ = timeout; }
void set_total_sensor(sensor::Sensor *sensor) { this->total_sensor_ = sensor; }

void set_total_pulses(uint32_t pulses);
void set_filter_mode(InternalFilterMode mode) { this->filter_mode_ = mode; }
void set_total_pulses(uint32_t pulses) { this->total_pulses_ = pulses; }

void setup() override;
void loop() override;
float get_setup_priority() const override { return setup_priority::DATA; }
float get_setup_priority() const override;
void dump_config() override;

protected:
enum StateChange { TO_LOW = 0, TO_HIGH, NONE };

static void gpio_intr(PulseMeterSensor *sensor);
void handle_state_change_(uint32_t now, uint32_t last_detected_edge_us, uint32_t last_valid_edge_us,
bool has_valid_edge);
static void edge_intr(PulseMeterSensor *sensor);
static void pulse_intr(PulseMeterSensor *sensor);

InternalGPIOPin *pin_{nullptr};
ISRInternalGPIOPin isr_pin_;
uint32_t filter_us_ = 0;
uint32_t timeout_us_ = 1000000UL * 60UL * 5UL;
sensor::Sensor *total_sensor_{nullptr};
InternalFilterMode filter_mode_{FILTER_EDGE};

Deduplicator<uint32_t> pulse_width_dedupe_;
Deduplicator<uint32_t> total_dedupe_;
// Variables used in the loop
bool initialized_ = false;
uint32_t total_pulses_ = 0;
uint32_t last_processed_edge_us_ = 0;

// This struct (and the two pointers) are used to pass data between the ISR and loop.
// These two pointers are exchanged each loop.
// Therefore you can't use data in the pointer to loop receives to set values in the pointer to loop sends.
// As a result it's easiest if you only use these pointers to send data from the ISR to the loop.
// (except for resetting the values)
struct State {
uint32_t last_detected_edge_us_ = 0;
uint32_t count_ = 0;
};
State state_[2];
volatile State *set_ = state_;
volatile State *get_ = state_ + 1;

volatile uint32_t last_detected_edge_us_ = 0;
volatile uint32_t last_valid_edge_us_ = 0;
volatile uint32_t pulse_width_us_ = 0;
volatile uint32_t total_pulses_ = 0;
volatile bool sensor_is_high_ = false;
volatile bool has_valid_edge_ = false;
volatile StateChange pending_state_change_{NONE};
// Only use these variables in the ISR
ISRInternalGPIOPin isr_pin_;
uint32_t last_edge_candidate_us_ = 0;
uint32_t last_intr_ = 0;
bool in_pulse_ = false;
bool last_pin_val_ = false;
};

} // namespace pulse_meter
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