Problems using LTM protocol

[casfra96]

Hi, I found two possible bugs using those configurations:

#define Telemetry_In 0 // Serial Port (default) - all protocols and #define PROTOCOL 6 // LTM

First problem

In the file AntTrack.ino, row 978, the function CheckStatusAndTimeouts(); // and service status LED is called. That function is definited in the file Utilities.ino, and contains the following code:

if ((millis() - hbGood_millis) > ((2*timeout_secs) * 1000)) { mavGood = false; hbGood = false; }

This code is ran regardless of the protocol selected in config.h file.

The problem is that the function LTM.ino does not upgrade the variable hbGood_millis, so the variable hbGood will always be false.

I thought of 3 possible solutions: 1) in the file AntTrack.ino, row 978, the function CheckStatusAndTimeouts(); // and service status LED , don't call the function if we are using LTM mode (check variable PROTOCOL);

2) same thing in the file Utilities.ino, we don't run the if statement mentioned before if we are using LTM mode (check variable PROTOCOL);

3) in the file LTM, after the while cycle: while (iLth==0) { // CheckStatusAndTimeouts(); iLth=Serial1.available(); } add hbGood_millis = millis();

I chose the 3th option and it is working correctly. Is it the best solution? Edit: after the while cyle in the file LTM.ino, it's already present the row: hbGood = 1;, so the best solution should be the second that i mentioned before. But in this case I lose the possibility to check a possible timeout (right?)

Second problem

I don't know why, but if I lost the signal (e.g. disconnecting the battery), lat and lon received values are still not zero. This will cause the variable gpsGood to remain True even though the aircraft's FC (and GPS also) was turned off. The other variables, however, immediately become zero (e.g. iSat ).

Possible solution: In file LTM.ino (row 133-136) change if ((!(Lat == 0)) && (!(Lon == 0))) { gpsGood=1; new_GPS_data = true; } to if ((!(Lat == 0)) && (!(Lon == 0)) && (iSat > 0) ) { gpsGood=1; new_GPS_data = true; }

[zs6buj]

casfra96

Thank you for the valuable feedback. Your diagnosis of the LTM issue was spot on. I added

hbGood_millis = millis();

into the the condition below

if ((!(Lat == 0)) && (!(Lon == 0))) {}

and also set new_GPS_data = false when the gps times out.

New version 2.20.4 uploaded on GitHub. I don't have the means to test right now, so your further feedback would be appreciated.

Eric zs6buj

[casfra96]

When i power off the aircraft, my TX16S continues to output the last detected latitude and longitude.

This will cause to enter in the if statement: if ((!(Lat == 0)) && (!(Lon == 0))) {.

I don't know if this problem only affects me, but I solved changing this line in LTM.ino with:

if ((!(Lat == 0)) && (!(Lon == 0)) && (iSat > 0) ) {

[zs6buj]

Glad you solved it. 😏

[casfra96]

I'm glad I could help :smile: