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18 December 2013 11:50 AM

MaximumTrainer Sr. Member

Total Posts: 123

Joined 2013-10-07

Hi,

In the document ANT_Device_profile, page 20 section 6 - Implementation Guidelines – Computed Heart Rate
It talks about implementing a system that shows a blank value when the user may have removed the monitor, or the user may not be wearing the heart rate monitor correctly.

Is there a standard period of time (accepted by ANT+) to use?. Right now i'm displaying a blank field on the Heart Rate value when I receive the same message 10 times in a row (2.5sec)
Thanks in advance,

Here is my current code :

/// DATA PRESENT ON ALL PAGES  (BYTES 4-5-6-7)
    stPage0Data.usBeatTime = (USHORT)stMessage.aucData[ucDataOffset+4];                  // Measurement time
    stPage0Data.usBeatTime |= (USHORT)stMessage.aucData[ucDataOffset+5] << 8;
    stPage0Data.ucBeatCount = (UCHAR)stMessage.aucData[ucDataOffset+6];                  // Measurement count
    stPage0Data.ucComputedHeartRate = (USHORT)stMessage.aucData[ucDataOffset+7];         // Computed heart rate


    qDebug() << "Time:" << stPage0Data.usBeatTime;
    qDebug() << "CountHR:" << hex <<  stPage0Data.ucBeatCount;
    qDebug() << "InstantHR:" << stPage0Data.ucComputedHeartRate;


    /// Check if the message is the same in a row for 10 messages, if so, user has removed the strap or incorrect strap placement on user.
    if ( (stPage0Data.usBeatTime == previousHeartBeatTime) && stPage0Data.ucBeatCount  == previousHeartBeatCount) {

        dataNotChanged++;
        if (dataNotChanged > 10) {
            /// EMIT HR
            emit HeartRateChanged(0);  /// TODO: Show "---" on interface instead of 0
        }
    }
    else {
        dataNotChanged = 0;
         /// EMIT HR
        emit HeartRateChanged(stPage0Data.ucComputedHeartRate);
    }

    /// Move current data to the past
    previousHeartBeatCount = stPage0Data.ucBeatCount;
    previousHeartBeatTime = stPage0Data.usBeatTime; 

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18 December 2013 12:51 PM #1

MaximumTrainer Sr. Member

Total Posts: 123

Joined 2013-10-07

I guess 2.5sec is okay for now, i'll test and put it up a bit if it's not working as expected.
assuming a low heart rate of 30 it would take 2sec to increase the heart beat count

[Edit: Nevermind I guess my reasoning was false, the time event will still increase even if you have a low beat count
Now i'm using this and seems to work fine :

/// Check if sensor cadence stopped using
    if (currentPage0.usLastCadence1024 == pastPage0.usLastCadence1024 && currentPage0.usCumCadenceRevCount  == pastPage0.usCumCadenceRevCount) {
        dataNotChanged++;
        if (dataNotChanged > MAX_MSG_REPEAT_CADENCE) {
            emit cadenceChanged(0);
        }
    }
    else {
        dataNotChanged = 0;
        /// Compute new cadence
        computeCadence();
    } 

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