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Newest RaceChrono doesn't seem to work with my RC3 + GPS output


I updated my trackbike android to 5.0.8 of RC and now it just sits at 'no satellite fix'. I have confirmed the GPS is working using a bluetooth GPS app and I have confirmed the output of the system as best I can.

Last time I had it out moving was I think RC V4.7.x? (going from memory) and I have not changed the code since.

You can find the raw data @

Any thoughts? I am heading out for first track day of the season tomorrow and ride the next day and was hoping to use this.

In the mean time I will see if any of my other devices have an older version to see if the version matters

Thanks, Jeff


  • Hello,

    I found 5.0.6 on my tablet (Nexus9) and it works. I have taken the APK from it and installed it on my bike Android (GalazyNexus) and the 5.0.6 works fine.

    So something between 5.0.6 and 5.0.8 seems to have changed how my output is read? I am working for now and will not update my bike Android for now.

    Thanks, Jeff
  • Hi @J_D_W,

    There are NMEA parser changes in v5.0.7, but after testing your raw output, I'm not sure how you managed to get that working on v5.0.6. I can certainly see problems with the raw data you've provided, that are not related to changes made in v5.0.7.

    Problem 1: You output 0x0D 0x0D 0x0A after every sentence. RaceChrono requires 0x0D 0x0A. The bluetooth GPS app is probably more lenient about it. After changing to 0x0D 0x0A the GPS data starts working in RaceChrono.

    Problem 2: Your RC3 checksums are wrong. If you put them to you see it calculates different ones.

  • OK, thanks ... guess there will be some trackside coding tonight. Will take a look, thanks

  • Did you get it working?
  • Sorry, track day didn't go as planned so been working on the bike and didn't get back to here.

    I have the output working with the newest app in the store. Removed the extra 0x0D easily. And the checksum was wrong due to a change I put in my code short time ago. I started to pass in the complete string including the leading $ and the $ was in the checksum. Once I started doing the checksum calc based on character 2+ (ignoring the $) then it got the right values

    Got bike repaired last night to running so time to re-add the and test on the bike again next trackday.

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