How to access Tempe on FR920XT

Former Member over 9 years ago

Hello,

i would like to know how i can access the Tempe by Monkey C on a Freerunner 920XT.

So specific i would like to know how this datafield does it: https://apps.garmin.com/de-DE/apps/c745113e-64a5-423e-bfe6-e2124089fa31
I played a bit around and got the idea that they implement the hole Ant+ connection procedure in it. So i searched for a documentation about the protocoll. But i didnt find anything so i am asking your help. If anybody knows something i would be glad to get some more informations.

Best regards Leachim.

Top Replies

travis.vitek over 9 years ago +1

But it is very hard without a debuging system, is there any way to debug this?

If you have an ANT+ USB Stick, you can connect to the sensor from the simulator, which makes it a lot easier to iterate.
…

All Replies

travis.vitek over 9 years ago

Have you tried setting the channel period to 8192?

I've done a lot of testing using SimulANT+, but noticed this morning that it doesn't seem to support simulating an environment sensor.

Travis

Former Member over 9 years ago

@sharkbait_au Thanks for the Device Profile it works exactly how i want to with 0,5Hz. But i am still searching for my failure what i am doing wrong with Antware II. I also just set Channel Assignment --> Slave
Channel ID --> 0,25,0
Basic --> Set Radio Frequency --> 57
Basic --> Channel Period --> 65535 (becouse of the defauls setting of the Sensor)
Auto-Open

with your template that Settings work perfect, so what do i miss?

My actual Code to talk with the Tempe is:

const DEVICE_TYPE = 25;		//Tempe
    const PERIOD = 65535;		//0,5 Hz


 function initialize()
    {
        // Get the channel
        chanAssign = new Ant.ChannelAssignment(
            Ant.CHANNEL_TYPE_RX_NOT_TX,
            Ant.NETWORK_PLUS);
        GenericChannel.initialize(method(:onMessage), chanAssign);

        // Set the configuration
        deviceCfg = new Ant.DeviceConfig( {
            :deviceNumber => 0,                 //Wildcard our search
            :deviceType => DEVICE_TYPE,
            :transmissionType => 0,
            :messagePeriod => PERIOD,
            :radioFrequency => 57,              //Ant+ Frequency
            :searchTimeoutLowPriority => 18,    //Timeout in 45s
            :searchThreshold => 0} );           //Pair to all transmitting sensors
        GenericChannel.setDeviceConfig(deviceCfg);

        data = new TempeData();
        searching = true;
        System.println("Ant initalized");
    }


function open()
    {
        // Open the channel
        GenericChannel.open();

        data = new TempeData();
        pastEventCount = 0;
        searching = true;
        System.println("Ant channel opened");
    }

    function closeSensor()
    {
        GenericChannel.close();
    }

  
    function onMessage(msg)
    {
    	System.println("Ant message recieved ID:"+ msg.messageId);
    	System.println("Device Typ:"+ msg.deviceType);
    	System.println("transmission Typ:"+ msg.transmissionType);
    	System.println("RSSI:"+ msg.rssi);
        // Parse the payload
        var payload = msg.getPayload();

        if( Ant.MSG_ID_BROADCAST_DATA == msg.messageId )
        {
            if( TempeDataPage.PAGE_NUMBER == (payload[0].toNumber() & 0xFF) )
            {
            System.println("Tempe datea recieved");
                // Were we searching?
                if(searching)
                {
                    searching = false;
                    // Update our device configuration primarily to see the device number of the sensor we paired to
                    deviceCfg = GenericChannel.getDeviceConfig();
                }
                var dp = new TempeDataPage();
                dp.parse(msg.getPayload(), data);
                // Check if the data has changed and we need to update the ui
                if(pastEventCount != data.eventCount)
                {
                    Ui.requestUpdate();
                    pastEventCount = data.eventCount;
                    System.println("new Tempe Data");
                }
                else
                {
                System.println("Tempe Data not new");
                }
            }
        }
        else if( Ant.MSG_ID_CHANNEL_RESPONSE_EVENT == msg.messageId )
        {
            if( Ant.MSG_ID_RF_EVENT == (payload[0] & 0xFF) )
            {
                if( Ant.MSG_CODE_EVENT_CHANNEL_CLOSED == (payload[1] & 0xFF) )
                {
                    // Channel closed, re-open
                    open();
                }
                else if( Ant.MSG_CODE_EVENT_RX_FAIL_GO_TO_SEARCH  == (payload[1] & 0xFF) )
                {
                    searching = true;
                    Ui.requestUpdate();
                }
            }
            else
            {
                //It is a channel response.
            }
        }
    }

So its pretty much exactly what the Mo2 Sample does.
When i launch it it does not recieve any broadcast data.

my DeviceX.txt sais just something like:

7203.828 { 279945562} Rx - [A4][03][40][00][01][07][E1]
  7203.906 { 279945640} Tx - [A4][01][4B][00][EE][00][00]
  7203.906 { 279945640} Rx - [A4][03][40][00][4B][00][AC]
  7233.828 { 279975562} Rx - [A4][03][40][00][01][01][E7]
  7233.828 { 279975562} Rx - [A4][03][40][00][01][07][E1]
  7233.906 { 279975640} Tx - [A4][01][4B][00][EE][00][00]
  7233.906 { 279975640} Rx - [A4][03][40][00][4B][00][AC]
  7263.828 { 280005562} Rx - [A4][03][40][00][01][01][E7]
  7263.828 { 280005562} Rx - [A4][03][40][00][01][07][E1]
  7263.906 { 280005640} Tx - [A4][01][4B][00][EE][00][00]
  7263.906 { 280005640} Rx - [A4][03][40][00][4B][00][AC]
  7293.828 { 280035562} Rx - [A4][03][40][00][01][01][E7]
  7293.828 { 280035562} Rx - [A4][03][40][00][01][07][E1]
  7293.906 { 280035640} Tx - [A4][01][4B][00][EE][00][00]
  7293.906 { 280035640} Rx - [A4][03][40][00][4B][00][AC]
  7323.828 { 280065562} Rx - [A4][03][40][00][01][01][E7]
  7323.828 { 280065562} Rx - [A4][03][40][00][01][07][E1]
  7323.906 { 280065640} Tx - [A4][01][4B][00][EE][00][00]
  7323.906 { 280065640} Rx - [A4][03][40][00][4B][00][AC]
  7353.828 { 280095562} Rx - [A4][03][40][00][01][01][E7]
  7353.828 { 280095562} Rx - [A4][03][40][00][01][07][E1]
  7353.906 { 280095640} Tx - [A4][01][4B][00][EE][00][00]
  7353.906 { 280095640} Rx - [A4][03][40][00][4B][00][AC]
  7383.828 { 280125562} Rx - [A4][03][40][00][01][01][E7]
  7383.828 { 280125562} Rx - [A4][03][40][00][01][07][E1]
  7383.906 { 280125640} Tx - [A4][01][4B][00][EE][00][00]
  7383.906 { 280125640} Rx - [A4][03][40][00][4B][00][AC]
  7413.828 { 280155562} Rx - [A4][03][40][00][01][01][E7]
  7413.828 { 280155562} Rx - [A4][03][40][00][01][07][E1]
  7413.906 { 280155640} Tx - [A4][01][4B][00][EE][00][00]
  7413.906 { 280155640} Rx - [A4][03][40][00][4B][00][AC]
  7443.828 { 280185562} Rx - [A4][03][40][00][01][01][E7]
  7443.828 { 280185562} Rx - [A4][03][40][00][01][07][E1]
  7443.906 { 280185640} Tx - [A4][01][4B][00][EE][00][00]
  7443.906 { 280185640} Rx - [A4][03][40][00][4B][00][AC]
  7473.828 { 280215562} Rx - [A4][03][40][00][01][01][E7]
  7473.828 { 280215562} Rx - [A4][03][40][00][01][07][E1]
  7473.906 { 280215640} Tx - [A4][01][4B][00][EE][00][00]
  7473.906 { 280215640} Rx - [A4][03][40][00][4B][00][AC]
  7503.828 { 280245562} Rx - [A4][03][40][00][01][01][E7]
  7503.828 { 280245562} Rx - [A4][03][40][00][01][07][E1]
  7503.906 { 280245640} Tx - [A4][01][4B][00][EE][00][00]
  7503.906 { 280245640} Rx - [A4][03][40][00][4B][00][AC]
  7533.828 { 280275562} Rx - [A4][03][40][00][01][01][E7]
  7533.828 { 280275562} Rx - [A4][03][40][00][01][07][E1]
  7533.906 { 280275640} Tx - [A4][01][4B][00][EE][00][00]
  7533.906 { 280275640} Rx - [A4][03][40][00][4B][00][AC]
  7563.828 { 280305562} Rx - [A4][03][40][00][01][01][E7]
  7563.828 { 280305562} Rx - [A4][03][40][00][01][07][E1]
  7563.906 { 280305640} Tx - [A4][01][4B][00][EE][00][00]
  7563.906 { 280305640} Rx - [A4][03][40][00][4B][00][AC]
  7593.828 { 280335562} Rx - [A4][03][40][00][01][01][E7]
  7593.844 { 280335578} Rx - [A4][03][40][00][01][07][E1]
  7593.906 { 280335640} Tx - [A4][01][4B][00][EE][00][00]
  7593.906 { 280335640} Rx - [A4][03][40][00][4B][00][AC]
  7623.828 { 280365562} Rx - [A4][03][40][00][01][01][E7]
  7623.828 { 280365562} Rx - [A4][03][40][00][01][07][E1]
  7623.906 { 280365640} Tx - [A4][01][4B][00][EE][00][00]
  7623.906 { 280365640} Rx - [A4][03][40][00][4B][00][AC]
  7653.828 { 280395562} Rx - [A4][03][40][00][01][01][E7]
  7653.828 { 280395562} Rx - [A4][03][40][00][01][07][E1]
  7653.906 { 280395640} Tx - [A4][01][4B][00][EE][00][00]
  7653.906 { 280395640} Rx - [A4][03][40][00][4B][00][AC]
  7683.328 { 280425062} Rx - [A4][03][40][00][01][01][E7]
  7683.328 { 280425062} Rx - [A4][03][40][00][01][07][E1]
  7683.406 { 280425140} Tx - [A4][01][4B][00][EE][00][00]
  7683.406 { 280425140} Rx - [A4][03][40][00][4B][00][AC]
  7713.078 { 280454812} Rx - [A4][03][40][00][01][01][E7]
  7713.078 { 280454812} Rx - [A4][03][40][00][01][07][E1]
  7713.109 { 280454843} Tx - [A4][01][4B][00][EE][00][00]
  7713.109 { 280454843} Rx - [A4][03][40][00][4B][00][AC]
  7743.078 { 280484812} Rx - [A4][03][40][00][01][01][E7]
  7743.078 { 280484812} Rx - [A4][03][40][00][01][07][E1]
  7743.109 { 280484843} Tx - [A4][01][4B][00][EE][00][00]
  7743.109 { 280484843} Rx - [A4][03][40][00][4B][00][AC]
  7772.578 { 280514312} Rx - [A4][03][40][00][01][01][E7]
  7772.578 { 280514312} Rx - [A4][03][40][00][01][07][E1]
  7772.609 { 280514343} Tx - [A4][01][4B][00][EE][00][00]
  7772.609 { 280514343} Rx - [A4][03][40][00][4B][00][AC]
  7802.578 { 280544312} Rx - [A4][03][40][00][01][01][E7]
  7802.578 { 280544312} Rx - [A4][03][40][00][01][07][E1]
  7802.609 { 280544343} Tx - [A4][01][4B][00][EE][00][00]
  7802.609 { 280544343} Rx - [A4][03][40][00][4B][00][AC]
  7832.578 { 280574312} Rx - [A4][03][40][00][01][01][E7]
  7832.578 { 280574312} Rx - [A4][03][40][00][01][07][E1]
  7832.609 { 280574343} Tx - [A4][01][4B][00][EE][00][00]
  7832.609 { 280574343} Rx - [A4][03][40][00][4B][00][AC]

Leachim

Former Member over 9 years ago

I think what you are maybe failing to realize is that you have received your data.

The payload is your data. You have successfully retrieved the data page
var payload = msg.getPayload();

The page numbers correspond to the Data pages from pg15 onwards in ANT_Device_Profile_Environment.pdf
TempeDataPage.PAGE_NUMBER == (payload[0].toNumber() & 0xFF)

You must extract the bytes & bits to decode the data. So if you wanted to extract the temperature for example (see 6.4, pg 16), you could do it like this...

var lsb = payload[6];
var msb = payload[7];
// Shift the MSB bits to their correct place
msb = msb << 8;
var currentTemp = msb + lsb;

If you wanted to read the low you also need to mask the bits, eg..

// 0xF0 = b11110000 Note bit order 7-0.
var low temp = (payload[4] & 0xF0) << 8 + payload[3];

Does that help?

Former Member over 9 years ago

I understood that the Payload is the Data and how to logically split it. That was pretty clear from the sample code. I also finished already some functions to do it. But thats not where i stuck.

I dont get to the point where i really recieve some Broadcast Data. There is just Ant.MSG_ID_CHANNEL_RESPONSE_EVENT that arrives

Leachim

Former Member over 9 years ago

Got ya.

So I looked a little closer. Your search priority is an incorrect value. Even though the documentation state a range of 0-12 in the past it did not allow higher than 10. Personally I leave both search params out of the config and allow the defaults.

Former Member over 9 years ago

@sharkbait_au

Your great! that was it! Big Thx!

Former Member over 8 years ago

Negative Values

Right now i have the following Problem:

positive temperatures worked pretty good but right now it is getting colder. And it seems that i have a big Problem with negative temperatures.

As an example the min Temp code is:

hidden function minTemp(payload)

        {

        // 0xF0 = b11110000 Note bit order 7-0.

        Sys.println( (payload[4] & 0xF0).toString() +"\n" );

        Sys.println( payload[3].toString() +"\n" );

        Sys.println(((payload[4] & 0xF0) << 4 + payload[3]).toString() +"\n" );

        return ((payload[4] & 0xF0) << 4 + payload[3]) / 10f;

        }

Console output:
240

20

3860

Return Value is: 386.000000

The Real Temperature (known from original Garmin Tempe Data Field) is: -23.5
I dont really get the point how i have to process the Value to get the correct neg value
3860 --> -235

does anyone see what i miss?

Thanks Michael

Former Member over 8 years ago

It's late and i'm tired. Deleted last message because thought I had missed something. I don't think I had. So yeah...

I think you need to shift the MSN 8 places. You are only shifting it 4. It needs to move 8 places to clear the LSB.

travis.vitek over 8 years ago

To get the lowest recorded value, we want to get the 4 most significant bits (1 nibble) of the 4th payload byte into the third nibble of a 12-bit value. It seems to me the logic should be...

// payload[3] = 0xBC;
   // payload[4] = 0xAF;
   // payload[5] = 0xDE;

   // remember to mask out the bits in payload[4] that we don't want to consider for each calculation
   // it is necessary because half of payload[4] is used for the min temp, and the other half is used
   // for the max temp.

   var min_temp = ((payload[4] & 0xF0) << 4) | payload[3];
   // result = (0xA0 << 4) | 0xBC;
   // result = (0xA00) | 0xBC;
   // result = 0xABC;

   var max_temp = (payload[5] << 4) | (payload[4] & 0x0F);
   // result = (0xDE << 4) | (0xAF & 0x0F)
   // result = (0xDE0) | (0x0F)
   // result = 0xDEF

Once you have built up the correct value from the bits, you can decode it to decimal...

function decode_12b_temperature(value)
{
    // handle special value
    if (value == 0x800) {
        value = null;
    }

    // handle negative values
    else if (value & 0x800) {
        // clear the sign bit
        value &= 0x7FF;

        // sign extend and scale
        value *= -0.1;
    }

    // handle positive values
    else {
        value *= 0.1;
    }

    return value;
}

Here is a test that you can use to verify it...

(:test) function test_decode_12b_temperature(logger)
{
    decode_12b_temperature(logger, 0x000, 0.0);
    decode_12b_temperature(logger, 0x001, 0.1);

    decode_12b_temperature(logger, 0x7FE, 204.6);
    decode_12b_temperature(logger, 0x7FF, 204.7);
    decode_12b_temperature(logger, 0x800, null);
    decode_12b_temperature(logger, 0x801, -0.1);
    decode_12b_temperature(logger, 0x802, -0.2);

    decode_12b_temperature(logger, 0xFFE, -204.6);
    decode_12b_temperature(logger, 0xFFF, -204.7);

    return true;
}

The calculation is the similar for a 16-bit value.

Travis

travis.vitek over 8 years ago

It should be noted that there appears to be a bit of rounding error at the extremes. The value 0x7FF becomes 204.600006 and 204.699997. You can avoid this by using double precision (multiply by -1.0d and 1.0d) if you need the actual value to be exact. Otherwise you can format the value to a string and fix the rounding error when you present it (with value.format("%.1f)).

Travis