Add DSM501A driver

doc/node_help/commands.rst

@@ -21,6 +21,7 @@ Alphabetic list
 - `display44780 <display44780.rst>`_
 - `display <display.rst>`_
 - `do_later <do_later.rst>`_
+- `dsm501a <dsm501a.rst>`_
 - `ds18b20 <ds18b20.rst>`_
 - `edge_counter <edge_counter.rst>`_
 - `ens16x <dev_ens16x.rst>`_

doc/node_help/dsm501a.rst

@@ -0,0 +1,43 @@
+dsm501a
+========
+
+..  code-block:: cpp
+
+    dsm501a(name, pm1_pin, pm25_pin);
+
+Create a new DSM501A dust sensor device.
+
+The sensor exposes two pulse outputs. The driver measures low-pulse occupancy
+for a 30 second sample window and publishes estimated concentrations for both
+channels as separate subtopics.
+
+Parameters
+----------
+
+- ``name``: the name it can be addressed via MQTT in the network.
+  Inside the code it can be addressed via IN(name).
+
+- ``pm1_pin``: where the DSM501A PM1 output pin is connected to
+
+- ``pm25_pin``: where the DSM501A PM2.5 output pin is connected to
+
+Outputs
+-------
+
+- ``pm1``: estimated PM1 concentration from the PM1 output.
+- ``pm25``: estimated PM2.5 concentration from the PM2.5 output.
+
+The driver uses a fixed 30 second measurement window, matching the common
+DSM501A low-pulse occupancy calculation pattern.
+
+Example
+-------
+
+..  code-block:: cpp
+
+    dsm501a(dust, D6, D5);
+
+In this example:
+
+- ``D6`` reads the DSM501A ``PM1`` output
+- ``D5`` reads the DSM501A ``PM2.5`` output

lib/node_types/esp/devices.ini

@@ -102,6 +102,10 @@ lib = milesburton/DallasTemperature@^4.0.5,https://github.com/sivar2311/OneWire
 ; stoffregen's latest 2.3.8 does not compile due to a wrong #endif - fixed in sivar2311/OneWire fork
 depends = dht11
 
+[dsm501a]
+filename = dsm501a
+class = DSM501A
+
 [bmp180]
 aliases = bmp085
 filename = barometer_bmp180

lib/node_types/esp/src/dev_dsm501a.cpp

@@ -0,0 +1,95 @@
+// dsm501a.cpp
+
+// Important to include Functional Interrupt as else it does not allow to
+// define a class-based (object specific) interrupt.
+#include <FunctionalInterrupt.h>
+#include "dev_dsm501a.h"
+
+DSM501A::DSM501A(const char* name, uint8_t pm1_pin, uint8_t pm25_pin) :
+    Device(name, 500000) {
+    _pm1_pin = pm1_pin;
+    _pm25_pin = pm25_pin;
+    add_subdevice(new Subdevice(F("pm1")));
+    add_subdevice(new Subdevice(F("pm25")));
+}
+
+void DSM501A::pm1_changed() {
+    uint32_t now_us = micros();
+    if(digitalRead(_pm1_pin) == LOW) {
+        if(!_pm1_low_active) {
+            _pm1_low_active = true;
+            _pm1_low_started_us = now_us;
+        }
+    } else if(_pm1_low_active) {
+        _pm1_lowpulse_us += now_us - _pm1_low_started_us;
+        _pm1_low_active = false;
+    }
+}
+
+void DSM501A::pm25_changed() {
+    uint32_t now_us = micros();
+    if(digitalRead(_pm25_pin) == LOW) {
+        if(!_pm25_low_active) {
+            _pm25_low_active = true;
+            _pm25_low_started_us = now_us;
+        }
+    } else if(_pm25_low_active) {
+        _pm25_lowpulse_us += now_us - _pm25_low_started_us;
+        _pm25_low_active = false;
+    }
+}
+
+float DSM501A::calculate_concentration(uint32_t lowpulse_us) const {
+    float ratio = (float)lowpulse_us / ((float)_sampletime_ms * 10.0f);
+    float concentration = 0.001915f * ratio * ratio + 0.09522f * ratio - 0.04884f;
+    if(concentration < 0.0f) concentration = 0.0f;
+    return concentration;
+}
+
+void DSM501A::start() {
+    pinMode(_pm1_pin, INPUT);
+    pinMode(_pm25_pin, INPUT);
+    _sample_started_ms = millis();
+
+    attachInterrupt(digitalPinToInterrupt(_pm1_pin), [&] () { pm1_changed(); }, CHANGE);
+    attachInterrupt(digitalPinToInterrupt(_pm25_pin), [&] () { pm25_changed(); }, CHANGE);
+
+    _started = true;
+}
+
+bool DSM501A::measure() {
+    uint32_t now_ms = millis();
+    if((uint32_t)(now_ms - _sample_started_ms) < _sampletime_ms) {
+        return false;
+    }
+
+    // Snapshot and reset both low-pulse accumulators at the sample boundary.
+    // If a pulse is still active, split it at "now" so the next window keeps
+    // measuring seamlessly without losing time.
+    uint32_t pm1_lowpulse_us = 0;
+    uint32_t pm25_lowpulse_us = 0;
+    uint32_t now_us = micros();
+
+    noInterrupts();
+    pm1_lowpulse_us = _pm1_lowpulse_us;
+    pm25_lowpulse_us = _pm25_lowpulse_us;
+
+    if(_pm1_low_active) {
+        pm1_lowpulse_us += now_us - _pm1_low_started_us;
+        _pm1_low_started_us = now_us;
+    }
+    if(_pm25_low_active) {
+        pm25_lowpulse_us += now_us - _pm25_low_started_us;
+        _pm25_low_started_us = now_us;
+    }
+
+    _pm1_lowpulse_us = 0;
+    _pm25_lowpulse_us = 0;
+    interrupts();
+
+    _sample_started_ms = now_ms;
+
+    value(0).printf("%.3f", calculate_concentration(pm1_lowpulse_us));
+    value(1).printf("%.3f", calculate_concentration(pm25_lowpulse_us));
+    return true;
+}

lib/node_types/esp/src/dev_dsm501a.h

@@ -0,0 +1,36 @@
+// dsm501a.h
+// DSM501A dust sensor using low-pulse occupancy on two output pins
+
+#ifndef _IOTEMPOWER_DSM501A_H_
+#define _IOTEMPOWER_DSM501A_H_
+
+#include <Arduino.h>
+#include <device.h>
+
+#define DSM501A_DEFAULT_SAMPLETIME_MS 30000
+
+class DSM501A : public Device {
+    private:
+        uint8_t _pm1_pin;
+        uint8_t _pm25_pin;
+        uint32_t _sampletime_ms = DSM501A_DEFAULT_SAMPLETIME_MS;
+        uint32_t _sample_started_ms = 0;
+
+        volatile uint32_t _pm1_lowpulse_us = 0;
+        volatile uint32_t _pm25_lowpulse_us = 0;
+        volatile uint32_t _pm1_low_started_us = 0;
+        volatile uint32_t _pm25_low_started_us = 0;
+        volatile bool _pm1_low_active = false;
+        volatile bool _pm25_low_active = false;
+
+        void pm1_changed();
+        void pm25_changed();
+        float calculate_concentration(uint32_t lowpulse_us) const;
+
+    public:
+        DSM501A(const char* name, uint8_t pm1_pin, uint8_t pm25_pin);
+        void start() override;
+        bool measure() override;
+};
+
+#endif // _IOTEMPOWER_DSM501A_H_

tests/conf_data.py

@@ -70,6 +70,7 @@
     {"device_name": "serial_hex", "example_syntax": "serial_hex(example_name, IOT_TEST_DIGITAL, IOT_TEST_DIGITAL_2);"},
     {"device_name": "soil_7in1", "example_syntax": "soil_7in1(example_name, IOT_TEST_DIGITAL, IOT_TEST_DIGITAL_2);"},
     {"device_name": "gmp343", "example_syntax": "gmp343(example_name, IOT_TEST_DIGITAL, IOT_TEST_DIGITAL_2);"},
+    {"device_name": "dsm501a", "example_syntax": "dsm501a(example_name, IOT_TEST_DIGITAL, IOT_TEST_DIGITAL_2);"},
 ]
 
 isolated_combinations_to_test = [