MCU8MASS-852 MCU8MASS-949 Lower power consumption and fix bug where MQTT prevented low power

Author: M65649

examples/mqtt_low_power/mqtt_low_power.ino

@@ -0,0 +1,134 @@
+/**
+ * @brief This example demonstrates how to use MQTT with low power.
+ */
+
+#include <Arduino.h>
+
+#include <ecc608.h>
+#include <led_ctrl.h>
+#include <log.h>
+#include <low_power.h>
+#include <lte.h>
+#include <mcp9808.h>
+#include <mqtt_client.h>
+#include <veml3328.h>
+
+#define USE_PSM true
+
+static char mqtt_pub_topic[128];
+
+bool initMQTTTopics() {
+    ECC608.begin();
+
+    // Find the thing ID and set the publish and subscription topics
+    uint8_t thingName[128];
+    uint8_t thingNameLen = sizeof(thingName);
+
+    // -- Get the thingname
+    uint8_t err = ECC608.getThingName(thingName, &thingNameLen);
+    if (err != ECC608.ERR_OK) {
+        Log.error("Could not retrieve thingname from the ECC");
+        return false;
+    }
+
+    sprintf(mqtt_pub_topic, "%s/sensors", thingName);
+
+    return true;
+}
+
+void setup() {
+    Log.begin(115200);
+    LedCtrl.begin();
+    LedCtrl.startupCycle();
+
+    Log.info("Starting MQTT with low power\r\n");
+
+    // First we retrieve the topics we're going to publish to, here using the
+    // ECC thingname with AWS
+    if (initMQTTTopics() == false) {
+        Log.error("Unable to initialize the MQTT topics. Stopping...");
+        while (1) {}
+    }
+
+    // Configure low power depending on whether to use power save mode or just a
+    // complete power down.
+#if USE_PSM
+    LowPower.configurePeriodicPowerSave(
+        PowerSaveModePeriodMultiplier::ONE_MINUTE,
+        1);
+#else
+    LowPower.configurePowerDown();
+#endif
+
+    Lte.begin();
+
+    // If we're using PSM, we only need to connect to the MQTT broker at the
+    // beginning, since the connection will remain active
+#if USE_PSM
+    MqttClient.beginAWS();
+
+    Log.infof("Connecting to broker");
+
+    while (!MqttClient.isConnected()) {
+        Log.rawf(".");
+        delay(500);
+    }
+
+    Log.raw(" OK!\r\n");
+#endif
+
+    Mcp9808.begin();
+    Veml3328.begin();
+}
+
+static uint32_t counter = 0;
+
+void loop() {
+
+    Mcp9808.wake();
+    Veml3328.wake();
+
+    // If we're not using PSM, all connections will be terminated when power
+    // down is issued, so we need to re-establish s connection
+#if !USE_PSM
+    MqttClient.beginAWS();
+
+    Log.infof("Connecting to broker");
+
+    while (!MqttClient.isConnected()) {
+        Log.rawf(".");
+        delay(500);
+    }
+
+    Log.raw(" OK!\r\n");
+#endif
+
+    char message_to_publish[8] = {0};
+    sprintf(message_to_publish, "%lu", counter);
+
+    bool published_successfully =
+        MqttClient.publish(mqtt_pub_topic, message_to_publish, AT_LEAST_ONCE);
+
+    if (published_successfully) {
+        Log.infof("Published message: %s.\r\n", message_to_publish);
+    } else {
+        Log.info("Failed to publish");
+    }
+
+    counter++;
+
+    Mcp9808.shutdown();
+    Veml3328.shutdown();
+
+    Log.info("Entering low power");
+    delay(10);
+
+#if USE_PSM
+    LowPower.powerSave();
+#else
+    LowPower.powerDown(60);
+#endif
+
+    Log.info("Woke up!");
+    delay(10000);
+}

examples/power_down/power_down.ino

@@ -11,27 +11,12 @@
 #include <mcp9808.h>
 #include <veml3328.h>
 
-#define SW0 PIN_PD2
-
-void buttonPressedInterrupt(void) {
-    if (PORTD.INTFLAGS & PIN2_bm) {
-        // Reset the interupt flag so that we can process the next incoming
-        // interrupt
-        PORTD.INTFLAGS = PIN2_bm;
-    }
-}
-
 void setup() {
     Log.begin(115200);
 
     LedCtrl.begin();
     LedCtrl.startupCycle();
 
-    // Configure SW0 for interrupt so we can wake the device up from sleep by
-    // pressing the button
-    pinConfigure(SW0, PIN_DIR_INPUT);
-    attachInterrupt(SW0, buttonPressedInterrupt, FALLING);
-
     // Now we configure the low power module for power down configuration, where
     // the cellular modem and the CPU will be powered down
     LowPower.configurePowerDown();

examples/power_save/power_save.ino

@@ -12,25 +12,12 @@
 #include <sequans_controller.h>
 #include <veml3328.h>
 
-#define SW0 PIN_PD2
-
-void buttonPressedInterrupt(void) {
-    if (PORTD.INTFLAGS & PIN2_bm) {
-        PORTD.INTFLAGS = PIN2_bm;
-    }
-}
-
 void setup() {
     Log.begin(115200);
 
     LedCtrl.begin();
     LedCtrl.startupCycle();
 
-    // Configure SW0 for interrupt so we can wake the device up from sleep by
-    // pressing the button
-    pinConfigure(SW0, PIN_DIR_INPUT);
-    attachInterrupt(SW0, buttonPressedInterrupt, FALLING);
-
     // Now we configure the power save configuration. Note that this has to be
     // done before calling Lte.begin().
     //

src/low_power.cpp

@@ -436,11 +436,9 @@ static void restorePinState(void) {
  * @brief Sets the pin state in order to minimize the power consumption. Will
  * not enable LDO.
  *
- * @param keep_ring_active Whether to keep ring line active (used in PSM).
+ * @param keep_modem_active Whether to keep modem lines active (used in PSM).
  */
-static void powerDownPeripherals(const bool keep_ring_active) {
-
-    // TODO: might keep SW0 in order to not mess with interrupt
+static void powerDownPeripherals(const bool keep_modem_active) {
 
     savePinState();
 
@@ -508,14 +506,26 @@ static void powerDownPeripherals(const bool keep_ring_active) {
 
     PORTA.DIR = 0x00;
     PORTB.DIR = PIN3_bm | PIN4_bm;
-    PORTC.DIR = 0x00;
+
+    if (keep_modem_active) {
+        PORTC.DIRCLR = PIN2_bm | PIN3_bm;
+    } else {
+        PORTC.DIR = 0x00;
+    }
+
     PORTD.DIR = 0x00;
     PORTE.DIR = 0x00;
     PORTF.DIR = 0x00;
 
     PORTA.OUT = 0x00;
     PORTB.OUT = 0x00;
-    PORTC.OUT = 0x00;
+
+    if (keep_modem_active) {
+        PORTC.OUTCLR = PIN2_bm | PIN3_bm;
+    } else {
+        PORTC.OUT = 0x00;
+    }
+
     PORTD.OUT = 0x00;
     PORTE.OUT = 0x00;
     PORTF.OUT = 0x00;
@@ -538,18 +548,17 @@ static void powerDownPeripherals(const bool keep_ring_active) {
     PORTB.PIN6CTRL = 0x0C;
     PORTB.PIN7CTRL = 0x0C;
 
-    PORTC.PIN0CTRL = 0x0C;
-    PORTC.PIN1CTRL = 0x0C;
     PORTC.PIN2CTRL = 0x04;
     PORTC.PIN3CTRL = 0x04;
-    PORTC.PIN4CTRL = 0x0C;
-    PORTC.PIN5CTRL = 0x04;
-    if (keep_ring_active) {
-        PORTC.PIN6CTRL = 0x01;
-    } else {
+
+    if (!keep_modem_active) {
+        PORTC.PIN0CTRL = 0x0C;
+        PORTC.PIN1CTRL = 0x0C;
+        PORTC.PIN4CTRL = 0x0C;
+        PORTC.PIN5CTRL = 0x04;
         PORTC.PIN6CTRL = 0x04;
+        PORTC.PIN7CTRL = 0x04;
     }
-    PORTC.PIN7CTRL = 0x04;
 
     PORTD.PIN0CTRL = 0x0C;
     PORTD.PIN1CTRL = 0x0C;
@@ -688,9 +697,6 @@ void LowPowerClass::configurePeriodicPowerSave(
 
 void LowPowerClass::powerSave(void) {
 
-    const uint8_t cell_led_state = digitalRead(LedCtrl.getLedPin(Led::CELL));
-    const uint8_t con_led_state  = digitalRead(LedCtrl.getLedPin(Led::CON));
-
     if (!retrieved_period) {
         // Retrieve the proper sleep time set by the operator, which may
         // deviate from what we requested
@@ -712,7 +718,7 @@ void LowPowerClass::powerSave(void) {
 
         // Retrieving the operator sleep time will call CEREG, which will
         // trigger led ctrl, so we just disable it again.
-        LedCtrl.off(Led::CELL, true);
+        // LedCtrl.off(Led::CELL, true);
     }
     if (!attemptToEnterPowerSaveModeForModem(30000)) {
         Log.error(
@@ -724,55 +730,36 @@ void LowPowerClass::powerSave(void) {
         powerDownPeripherals(true);
         SLPCTRL.CTRLA |= SLPCTRL_SMODE_PDOWN_gc | SLPCTRL_SEN_bm;
 
-        // enableLDO();
+        enableLDO();
         sleep_cpu();
 
         // Will sleep here until we get the RING line activity and wake up
-        // disableLDO();
+        disableLDO();
 
         SLPCTRL.CTRLA &= ~SLPCTRL_SEN_bm;
         powerUpPeripherals();
 
         modem_is_in_power_save = false;
     }
 
-    SequansController.setPowerSaveMode(0, NULL);
-
-    // Pins are active low
-    if (!cell_led_state) {
-        LedCtrl.on(Led::CELL, true);
-    } else {
-        LedCtrl.off(Led::CELL, true);
-    }
+    // LedCtrl.on(Led::CELL, true);
 
-    if (!con_led_state) {
-        LedCtrl.on(Led::CON, true);
-    } else {
-        LedCtrl.off(Led::CON, true);
-    }
+    SequansController.setPowerSaveMode(0, NULL);
 }
 
 void LowPowerClass::powerDown(const uint32_t power_down_time_seconds) {
 
-    const unsigned long start_time_ms = millis();
-
     SLPCTRL.CTRLA |= SLPCTRL_SMODE_PDOWN_gc | SLPCTRL_SEN_bm;
 
     Lte.end();
 
-    uint32_t remaining_time_seconds =
-        power_down_time_seconds -
-        (uint32_t)(((millis() - start_time_ms) / 1000.0f));
-
-    // Need to power down the peripherals here as we want to grab the time
-    // (millis()) from the timer before disabling it
+    // TODO: somehow this prevents the modem to sleep...
     powerDownPeripherals(false);
 
     enablePIT();
     enableLDO();
 
-    // TODO: might want to just have the remaining time in seconds to be the
-    // power_down_time_seconds to prevent issues with millis() overflowing
+    uint32_t remaining_time_seconds = power_down_time_seconds;
 
     while (remaining_time_seconds > 0) {
 
@@ -793,7 +780,6 @@ void LowPowerClass::powerDown(const uint32_t power_down_time_seconds) {
 
     powerUpPeripherals();
 
-    // TODO: should we keep this here?
     while (!Lte.begin()) {}
 }
 

src/lte.cpp

@@ -1,6 +1,6 @@
+#include "lte.h"
 #include "led_ctrl.h"
 #include "log.h"
-#include "lte.h"
 #include "mqtt_client.h"
 #include "sequans_controller.h"
 
@@ -255,6 +255,9 @@ void LteClass::end(void) {
 
     if (SequansController.isInitialized()) {
 
+        // Terminate active connections (if any)
+        MqttClient.end();
+
         SequansController.unregisterCallback(TIMEZONE_CALLBACK);
         SequansController.writeCommand(AT_DISCONNECT);
 
@@ -300,8 +303,8 @@ String LteClass::getOperator(void) {
     }
 
     // Remove the quotes
-    char* buffer            = id + 1;
-    id[strnlen(buffer, 47)] = '\0';
+    char* buffer                        = id + 1;
+    id[strnlen(buffer, sizeof(id) - 1)] = '\0';
 
     return String(buffer);
 }

src/lte.h

@@ -5,6 +5,7 @@
 #ifndef LTE_H
 #define LTE_H
 
+#include <Arduino.h>
 #include <stdint.h>
 
 class LteClass {
@@ -20,7 +21,7 @@ class LteClass {
     /**
      * @brief Singleton instance.
      */
-    static LteClass &instance(void) {
+    static LteClass& instance(void) {
         static LteClass instance;
         return instance;
     }