There is a problem with the movement wakeup flow when the sensor is shaken for more than 2 seconds

Question

Behavior: If I shake the sensor for more than 2 seconds, the sensor wakes up and starts blinking. After 5 seconds, the device turns off and then immediately turns back on again. And starts blinking again and after 5 seconds, it will enter into power-off mode. Since I don't have a Movesense programmer, I can't see the hardware logs that show what's going on.

For reference, I am attaching a video link of testing a sample example of the movement_wakeup_app.

video link

Firmware File: Firmware file

Hardware Specification

Sensor model: Movesense "BIG_MEM"

HWCONFIG: SS2_NAND

Data memory: 128 MB FLASH

1-Wire master:-YES

Remarks:-The movesense sensor variant is BIG_MEM.

Movesense-device-lib version:

This is a sample code given by Movesense in which we only do a little bit of modification like

// Time between wake-up and going to power-off mode

#define AVAILABILITY_TIME 5000

// LED blinking period in advertising mode

#define LED_BLINKING_PERIOD 1000

#include "movesense.h"

#include "MovementWakeupApp.h"
#include "common/core/debug.h"

#include "component_led/resources.h"
#include "component_lsm6ds3/resources.h"
#include "ui_ind/resources.h"
#include "system_mode/resources.h"

const char* const MovementWakeupApp::LAUNCHABLE_NAME = "MoveWakeupApp";

// Time between wake-up and going to power-off mode
#define AVAILABILITY_TIME 5000

// Time between turn on AFE wake circuit to power off
// (must be LED_BLINKING_PERIOD multiple)
#define WAKE_PREPARATION_TIME 5000

// LED blinking period in advertising mode
#define LED_BLINKING_PERIOD 1000

MovementWakeupApp::MovementWakeupApp():
    ResourceClient(WBDEBUG_NAME(__FUNCTION__), WB_EXEC_CTX_APPLICATION),
    LaunchableModule(LAUNCHABLE_NAME, WB_EXEC_CTX_APPLICATION),
    mTimer(wb::ID_INVALID_TIMER),
    counter(0)
{
}

MovementWakeupApp::~MovementWakeupApp()
{
}

bool MovementWakeupApp::initModule()
{
    mModuleState = WB_RES::ModuleStateValues::INITIALIZED;
    return true;
}

void MovementWakeupApp::deinitModule()
{
    mModuleState = WB_RES::ModuleStateValues::UNINITIALIZED;
}

bool MovementWakeupApp::startModule()
{
    mModuleState = WB_RES::ModuleStateValues::STARTED;

    setShutdownTimer();

    // Subscribe to Whiteboard routing table changes
    asyncSubscribe(WB_RES::LOCAL::NET());

    return true;
}

void MovementWakeupApp::stopModule()
{
    // Stop LED timer
    stopTimer(mTimer);
    mTimer = wb::ID_INVALID_TIMER;
    mModuleState = WB_RES::ModuleStateValues::STOPPED;
}

void MovementWakeupApp::onNotify(wb::ResourceId resourceId,
                                 const wb::Value& value,
                                 const wb::ParameterList& parameters)
{
    // Confirm that it is the correct resource
    if (resourceId.localResourceId != WB_RES::LOCAL::NET::LID)
        return;

    // Get whiteborad routing table notification
    uint8_t data = WB_RES::LOCAL::NET::EVENT::ParameterListRef(parameters).getNotificationType();

    // if there is whiteboard connection, stop timer
    if (data == WB_RES::RoutingTableNotificationTypeValues::ROUTE_NOTIFICATION_NEW)
    {
        stopTimer(mTimer);
        mTimer = wb::ID_INVALID_TIMER;
        return;
    }

    // if whiteboard connection lost, prepare to shutdown
    if (data == WB_RES::RoutingTableNotificationTypeValues::ROUTE_NOTIFICATION_LOST)
    {
        setShutdownTimer();
    }
}

void MovementWakeupApp::setShutdownTimer()
{
    // Start timer
    mTimer = startTimer(LED_BLINKING_PERIOD, true);

    // Reset timeout counter
    counter = 0;
}

void MovementWakeupApp::onTimer(wb::TimerId timerId)
{
    counter = counter + LED_BLINKING_PERIOD;

    if (counter < AVAILABILITY_TIME)
    {
        asyncPut(WB_RES::LOCAL::UI_IND_VISUAL(), AsyncRequestOptions::Empty,
                 WB_RES::VisualIndTypeValues::SHORT_VISUAL_INDICATION);
        return;
    }

    if (counter == AVAILABILITY_TIME)
    {
        // Prepare AFE to wake-up mode
        WB_RES::WakeUpState wakeupState;
        wakeupState.level = 2;
        wakeupState.state = 1; // Movement
        asyncPut(WB_RES::LOCAL::COMPONENT_LSM6DS3_WAKEUP(),
                 AsyncRequestOptions(NULL, 0, true), wakeupState);

        // Make PUT request to switch LED on
        asyncPut(WB_RES::LOCAL::COMPONENT_LED(), AsyncRequestOptions::Empty, true);

        // Make PUT request to enter power off mode
        asyncPut(WB_RES::LOCAL::SYSTEM_MODE(), AsyncRequestOptions::Empty,
                 WB_RES::SystemModeValues::FULLPOWEROFF);
    }
}

Expected: as soon as the movesense sensor shakes, the sensor wakes and after 5 seconds it'll enter into full power-off mode.

Answer 1

The reason for this behavior is that the sensor is set to "FullPowerOff" mode while the accelerometer is still in "MOVEMENT detected"-state and interrupt line is pulled low. The current accelerometer chip works internally in 1.6Hz low power mode when in WAKEUP detection mode. This means that it takes some multiples of 0.7s for the interrupt line to reset back to high after motion is detected. In your firmware you are waking on movement and immediately powering off before the accelerometer has time to reset its output

One way to avoid this is to SUBSCRIBE to MOVEMENT state (/System/States/0) before going to power-off, and only power off the sensor if there is no movement detected for at least a few seconds.

Full disclosure: I work for the Movesense team