25 April, 2018 at 06:29 #57640
Hi good ppl in this forum:
Recently I bought a new F3FC to replace my old naze version for my mini tricopter, I was excited to try iNav after reading some guys here have decent results with, unfortunately I have an issue with a GPS Holybro micro M8N( with compass), the GPS works fine connected via to I2C 3.3V and UART3(TX/RX) until I plug the battery, as soon it is plugged the GPS loses Fix, this is happening with Triflight 0.7 beta 3 and also with iNav 1.9.x.
If I power the GPS with 5V via UART3(-/+) the barometer becomes RED.
Any ideas what is happening here?. I’m very frustrated with this New board.
The radio receiver is a CPPM connected on PPM/PWM6
OSD is a minimOSD connected via UART1
UART2 is free
UART3 GPS RX/TX
I2C GPS( +/-)/Compass on (sda/sclk)25 April, 2018 at 15:22 #57645LitterBugParticipant
I’ve used a similar GPS with mine with no issues with V+ wired to 5V. I also had a baro wired to 3.3v on the I2C bus at the same time. Is it possible that the GPS is too close to FPV or RX gear that may be causing interference with the GPS? I’ve attached some pics from my initial testing where you should be able to see how it was wired.
Attachments:25 April, 2018 at 15:38 #57649Kevin_ErikModerator
Whats the current draw with and without it the GPS attached to the Tri. Doing that comparison should give you the GPS’s true wattage. Keep in mind that some devices draw more current when they initially startup.
Also try powering up the GPS remotely from the Tri but still using the same PS as before. (think ext cable) If your having interferance it should all but disapear once the GPS is outside of the Tri.25 April, 2018 at 23:17 #57654
Will check the current draw today, my board is the F3FC (frame), honestly didn’t think about interference,and TX/RX is my daily job LOL,my RX antennas are pretty close to the GPS, but in a small frame like the mini, where is the best place to put a GPS without causing interference?
I will try pointing the antennas down to see.
thank you for your answers, I will try later and back to you guys, I really appreciate your posts here.
jc26 April, 2018 at 17:35 #57666LitterBugParticipant
Ah the integrated frame/FC. Pretty much the same hardware but with the baro already included and the gyro/accelerometer orientation is 180 degrees different. Current should not be an issue. I’d focus more on getting the GPS as far away from any other signals as possible. Maybe on it’s own mast.
LB26 April, 2018 at 19:11 #57667Kevin_ErikModerator
That’s why i suggested placing it on an extension cable at first. This way the GPS antenna is mobile and can be tested without having to turn everything off. Should be able to find the sweet-spot with a minimum of fuss.26 April, 2018 at 20:43 #57668
Sorry didn’t have time to post, based in bench test, interference was the issue, I move my RX antennas across the arms with the GPS module sitting on top of the mini tricopter frame and let it on for about 20min, not GPS drops during the test, this was without FPV gear, but I don’t think L1 and L2 will cause any interference ( or harmonic interf) with 5.8Ghz.
I will try later on my yard to see if it work and I will back with you guys later to close this helpful discussion.
thank you, everyone, for your help.!
PS. Current draw was as I was expecting basically no draw with GPS on.
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